Student Loan Calculator

See your standard monthly student loan payment and how much interest you will pay over the repayment term.

How the Student Loan Calculator works

This calculator amortizes your student loan balance into a level monthly payment using the standard fixed-payment formula, then shows the lifetime interest that schedule produces. It models the standard 10-year (or extended fixed) plan that the U.S. Department of Education uses as the default for federal loans - not an income-driven plan, whose payment moves with your income and family size.

The engine uses the amortization formula:

M = P x [ i(1+i)ⁿ ] / [ (1+i)ⁿ - 1 ]

• M = your fixed monthly payment
• P = principal (the loan balance entered, including any interest that has already capitalized)
• i = the monthly interest rate = annual rate / 12 (so 6.5% becomes 0.065 / 12 = 0.00541667)
• n = total number of monthly payments = years x 12 (10 years = 120)

Step by step, the tool does the following:

1. Converts your annual rate to a monthly rate and your term in years to months.
2. Solves the formula above for the level payment M.
3. Builds a month-by-month amortization schedule: each month it charges interest on the current balance, applies the rest of M to principal, and rolls the balance forward.
4. Sums every interest charge to report total interest and total repaid (M x n).

Edge cases it handles: a 0% rate falls back to simple division (P / n) so it never divides by zero; it accepts terms beyond the standard 10 years to model extended repayment; and because P is whatever balance you type, you can enter your post-capitalization balance to see how unpaid grace-period interest inflates the payment. What it deliberately does not model is the federal-program layer: it does not recalculate payments under income-driven repayment, apply PSLF or IDR forgiveness write-offs, or follow variable private rates. Treat its output as your standard-plan baseline - the full-cost number every income-driven plan is measured against.

]]>

Example calculation

Here are three fully worked student loan scenarios, each recomputed with the standard amortization formula.

Example 1 - Standard 10-year plan. A $30,000 federal balance at 6.5% over 10 years (n = 120). The monthly payment is $340.64. Over 120 payments you repay $40,877.27, so total interest is $10,877.27 - about 36% of what you borrowed.

Example 2 - Stretching to 20 years. Same $30,000 at 6.5%, but on a 20-year extended term (n = 240). The payment drops to $223.67, which feels easier month to month. But you now pay $53,681.27 in total, meaning $23,681.27 of interest - more than double Example 1 for the exact same debt. This is the core trade-off of extended repayment.

Example 3 - A bigger private loan. A $45,000 balance at 7.5% over 15 years (n = 180). The payment is $417.16, total repaid is $75,088.00, and interest is $30,088.00. Notice the interest now nearly equals the original principal, because a higher private rate and a longer term compound on each other - and a private loan carries none of the federal income-driven or forgiveness backstops.

Scenario	Balance	Rate	Term	Monthly	Total interest	Total repaid
1. Standard federal	$30,000	6.5%	10 yr	$340.64	$10,877.27	$40,877.27
2. Extended	$30,000	6.5%	20 yr	$223.67	$23,681.27	$53,681.27
3. Larger private	$45,000	7.5%	15 yr	$417.16	$30,088.00	$75,088.00

The pattern is consistent for education debt: a lower monthly payment almost always means a higher lifetime cost, because you are paying interest on the balance for more years. Adding even $50 a month to Example 1 pays the $30,000 off in roughly 100 months instead of 120 and saves close to $1,985 in interest - and because federal and most private student loans have no prepayment penalty, every extra dollar lands on principal.

]]>

Tips for using the Student Loan Calculator

• <strong>Enter your capitalized balance, not your original loan amount.</strong> If interest accrued during school or your grace period and then capitalized, your real starting principal is higher than what you borrowed - type that number in or your payment estimate will be too low.
• <strong>Make voluntary interest-only payments during school and the grace period on unsubsidized loans.</strong> Unsubsidized interest accrues from disbursement; paying just the interest keeps it from capitalizing and permanently inflating your principal. Subsidized loans need no such payment - the government covers in-school interest.
• <strong>Target the highest interest rate first when paying extra, not the smallest balance.</strong> Federal loans from different award years carry different fixed rates - sort your loans by rate and attack the top one (the avalanche method) to save the most.
• <strong>Tell your servicer in writing to apply extra payments to principal on a specific high-rate loan.</strong> By default many servicers spread an overpayment across all your loans or just advance your due date, which wastes the benefit.
• <strong>Do not refinance federal loans just to shave a point off the rate.</strong> Refinancing converts them to a private loan and permanently forfeits income-driven repayment, deferment, forbearance, and forgiveness like PSLF - protections you cannot buy back at any price.
• <strong>Refinance only the private loans you already hold, or refinance federal loans solely if you have stable high income and are certain you will never need IDR or PSLF.</strong>
• <strong>If you work for a government or qualifying nonprofit employer, model the standard plan here but pursue PSLF separately.</strong> PSLF rewards staying on a qualifying income-driven plan for the required years, so the lowest standard payment is not always your goal.
• <strong>Run the standard 10-year payment as your baseline even if you plan to use IDR.</strong> It is the number every IDR plan is measured against and shows the true full cost if you never reach forgiveness.
• <strong>Check whether your servicer offers an autopay interest-rate discount</strong> (commonly 0.25 percentage points on federal loans) and re-run the calculator with the lower rate to see the savings.
• <strong>Re-run the math after each capitalization event.</strong> Leaving an IDR plan, exiting a deferment or forbearance, or consolidating can capitalize accrued interest and quietly raise your payment - enter the new, higher balance to see the real number.

Federal vs private student loans: why the loan type changes everything

Federal and private student loans can carry similar rates, but only federal loans come with repayment protections that disappear the moment you refinance into a private loan. The calculator math is identical for both - the same amortization formula - but the decisions around that math are completely different, and that is the whole reason a student loan needs its own tool instead of a generic loan calculator.

Federal loans (Direct Subsidized, Direct Unsubsidized, and PLUS) offer income-driven repayment, deferment and forbearance, and potential forgiveness through programs like Public Service Loan Forgiveness (PSLF) and IDR forgiveness. Private loans, issued by banks and other lenders, are a straight contract: a balance, a rate, and a term, with few of those safety nets.

Feature	Federal loan	Private loan
Income-driven repayment	Yes	Rarely
Forgiveness (PSLF, IDR forgiveness)	Yes, if eligible	No
Deferment / forbearance	Yes, formal options	Lender discretion
Rate type	Fixed, set annually for new loans	Fixed or variable
Credit check / cosigner	Not for most undergrads	Usually required

This calculator shows the standard fixed plan for either type. Use it as your baseline cost, then weigh the protections above before changing anything - because for federal borrowers, the cheapest-looking option on paper can be the most expensive once you account for losing IDR or forgiveness.

Subsidized vs unsubsidized, the grace period, and interest capitalization

The single biggest hidden cost in student loans is interest that accrues while you are not paying and then capitalizes - it gets added to your principal, so you start paying interest on interest.

On subsidized federal loans, the government covers the interest while you are enrolled at least half-time and during the grace period, so nothing capitalizes if you re-enter repayment on time. On unsubsidized loans (and all private loans), interest accrues from disbursement - all through school and the grace period. If you do not pay that interest, it capitalizes, usually when repayment begins.

Worked example: a $27,000 unsubsidized loan at 5% accrues roughly $1,350 per year. Over four years of school plus a six-month grace period (4.5 years), that is about $6,075 of unpaid interest. If it capitalizes, your starting balance becomes $33,075, not $27,000. On a 10-year plan the payment rises from $286.38 to $350.81 a month - $64.43 more every month for a decade, purely because interest was allowed to capitalize. To see this yourself, enter $33,075 instead of $27,000 in the calculator. The lesson is specific to education debt: voluntary interest payments during school are the cheapest dollars you will ever put toward the loan, and they are the one move a subsidized borrower never has to make.

Standard 10-year plan vs income-driven repayment (IDR)

This tool computes the standard 10-year plan; income-driven repayment is a separate federal system that sets your payment as a percentage of discretionary income instead of from your balance. Knowing the difference tells you which number actually applies to you.

The standard plan, modeled here, gives you a fixed payment that retires the full balance in 10 years (or a fixed extended term). IDR plans recalculate your payment each year based on income and family size; payments can be far lower, but a longer payoff means more interest, and any remaining balance may be forgiven after the plan's required years (the forgiven amount may be taxable depending on the federal rules in effect when it is forgiven). IDR depends on personal financial details this calculator does not collect, and the specific plans and formulas change with federal policy - confirm current options at the source linked below.

Use the standard payment here as your benchmark: every IDR plan is judged against it, and it shows the full, no-forgiveness cost. If the standard payment is comfortable, the standard plan usually costs the least overall. If it is not, IDR may bridge the gap, especially if you are pursuing PSLF. To pressure-test affordability against your other obligations, run your debt-to-income ratio and your take-home pay first - IDR uses discretionary income, so what you actually keep matters more than your gross salary.

The refinance trade-off: a lower rate vs losing federal protections

Refinancing can genuinely lower your rate and payment, but refinancing a federal loan converts it to a private loan and permanently destroys income-driven repayment, deferment rights, and forgiveness eligibility - you cannot undo it.

The dollar appeal is real. Refinancing a $50,000 balance from 7% to 5% on a 10-year term drops the payment from $580.54 to $530.33 and cuts lifetime interest from $19,665.09 to $13,639.31 - about $6,026 saved.

$50,000, 10-year	Before (7%)	After refi (5%)
Monthly payment	$580.54	$530.33
Total interest	$19,665.09	$13,639.31
Federal protections	Kept	Lost forever

That $6,026 is the price the lender pays you to give up IDR, PSLF, and federal deferment. The trade only makes sense if you (1) already hold private loans, or (2) have stable, high income and are certain you will never need those safety nets or pursue forgiveness. If there is any chance you will work in public service or hit a rough income year, keeping federal loans is usually worth more than the rate cut - the protections have no resale market, and you only learn their value when you need them.

Common mistakes people make with student loan math

Most student loan miscalculations come from using the wrong balance or assuming the lowest monthly payment is the best deal.

• Using the original loan amount instead of the capitalized balance. If interest accrued and capitalized, your real principal is higher - the payment you compute will be too low.
• Treating the standard payment as your IDR payment. They are unrelated; IDR is income-based and this tool does not model it.
• Refinancing federal loans for a small rate cut. Saving a few thousand dollars while forfeiting forgiveness and IDR is often a bad trade.
• Paying extra without instructing the servicer. Overpayments may be spread across loans or just advance your due date unless you specify principal on a chosen loan.
• Chasing the longest term to lower the monthly payment. As Example 2 above showed, 20 years instead of 10 more than doubled the interest on the same $30,000 debt.
• Ignoring the autopay rate discount that quietly lowers your effective federal rate.

When you compare a few payoff strategies side by side across several loans at different rates, the debt payoff calculator helps you see avalanche versus snowball - and for student debt, avalanche (highest rate first) almost always wins.

How to do it by hand or in a spreadsheet

You can reproduce this calculator in Excel or Google Sheets with one PMT formula. For a $30,000 loan at 6.5% over 10 years:

• Monthly payment: =PMT(0.065/12, 10*12, -30000) returns 340.64. Divide the annual rate by 12 for the monthly rate, multiply years by 12 for the number of payments, and enter the balance as a negative present value so the result comes back positive.
• Total repaid: =PMT(0.065/12,120,-30000)*120 returns 40,877.27.
• Total interest: =PMT(0.065/12,120,-30000)*120-30000 returns 10,877.27.
• Remaining balance after, say, 36 payments: =FV(0.065/12,36,340.64,-30000).

By hand, the formula is M = P x [ i(1+i)ⁿ ] / [ (1+i)ⁿ - 1 ]. With i = 0.00541667 and n = 120, (1+i)ⁿ works out to about 1.9122, so M = 30000 x (0.00541667 x 1.9122) / (1.9122 - 1) = 30000 x 0.010358 / 0.9122 = 340.64. One note for student loans: servicers usually accrue interest daily (balance x rate / 365 x days in the period), so your real statement may differ by a few cents to a few dollars a month from this monthly model. To see how the (1+i)ⁿ growth factor drives the whole result, the compound interest calculator isolates that term.

Is your student loan payment good? Benchmarks to judge by

A common rule of thumb is that your total student loan payment should stay at or below about 8% to 10% of your gross monthly income, and your total debt payments below roughly 36% of gross income. These are guidelines, not laws, but they flag when a loan is too heavy.

Quick reference points using the calculator's default ($35,000 at 6% over 10 years = $388.57 a month, $11,628.61 interest):

Gross monthly income	8% of income	10% of income
$3,500	$280	$350
$4,500	$360	$450
$6,000	$480	$600

If the standard 10-year payment exceeds about 10% of your gross income, that is a signal to consider income-driven repayment (for federal loans) rather than simply stretching the term, which inflates total interest without any forgiveness backstop. A healthy sign is when extra payments still fit your budget - even modest extra principal shortens the term meaningfully. Confirm the affordability picture with your take-home pay rather than gross income, since taxes and benefits reduce what you actually have to spend.

Student loan quick reference: monthly payment and total interest by balance and rate (10-year standard plan)

This table shows the level monthly payment and lifetime interest for a standard 10-year (120-month) fixed repayment, the federal default plan. Every figure is recomputed with the amortization formula payment = P x r / (1 - (1 + r)^-n), where r is the monthly rate and n is 120. Use it to estimate cost before running your exact loan. Format is monthly payment / total interest.

Balance	At 5%	At 6%	At 7%
$10,000	$106 / $2,728	$111 / $3,322	$116 / $3,933
$25,000	$265 / $6,820	$278 / $8,306	$290 / $9,833
$40,000	$424 / $10,911	$444 / $13,290	$464 / $15,732
$60,000	$636 / $16,367	$666 / $19,935	$697 / $23,598

Reading it: at the same balance, each 1-point rate increase adds noticeably to interest, and bigger balances multiply the gap. A $60,000 loan costs about $7,231 more in interest at 7% than at 5%. Stretching beyond 10 years lowers the payment but sharply raises total interest, so for student debt, prefer the shortest standard term you can afford - and if that term is unaffordable, reach for federal IDR rather than a longer fixed term, since only IDR carries forgiveness.

Related on this site

Loan Calculator · Debt Payoff Calculator · Debt-to-Income Ratio Calculator · Take-Home Pay Calculator · Compound Interest Calculator · Investment Calculator

For a related deep dive, see Federal Student Aid (studentaid.gov).

Student Loan Calculator — frequently asked questions

Does this cover income-driven plans?

No — this models a standard fixed repayment. Income-driven plans depend on income and family size.

Should I refinance?

Refinancing can lower the rate but federal protections are lost. Compare carefully.

Does this include income-driven repayment?

No — IDR plans depend on income and family size. This shows the standard fixed plan for comparison.

What is loan capitalization?

Unpaid interest being added to your principal, after which you pay interest on interest.

How much interest does a $25,000 unsubsidized loan rack up during a 6-month grace period at 6%?

About $750 accrues over a 6-month grace period. <p>Unsubsidized loans charge interest the whole time, including the grace period. At 6%, $25,000 accrues roughly $25,000 x 6% / 2 = $750 in six months. If that $750 capitalizes (gets added to principal), your balance becomes $25,750 and you then pay interest on interest. Paying that $750 before repayment starts stops capitalization. A subsidized loan would accrue $0 during this window because the government covers it.</p>

What does interest capitalization cost on a $30,000 loan at 6% after a 6-month grace period?

Capitalizing the grace-period interest costs roughly $1,200 in extra lifetime interest. <p>Six months at 6% on $30,000 accrues about $900. If unpaid and capitalized, your new balance is $30,900, raising the 10-year payment from about $333.06 to $343.05. Over 120 months that drives total cost higher by roughly $1,199 versus paying the $900 while in school. Run both balances in the <a href="/student-loan-calculator/">student loan calculator</a> to see the gap.</p>

Is refinancing a $50,000 federal loan from 8% to 5.5% worth it?

Refinancing $50,000 from 8% to 5.5% saves about $7,681 in interest over 10 years but permanently forfeits federal protections. <p>At 8% over 10 years you pay about $22,797 in interest ($606.64/month); at 5.5% it drops to about $15,116 ($542.63/month). The $7,681 saving is real, but refinancing federal loans into a private loan ends IDR, PSLF eligibility, and federal deferment for good. It is usually worth it only for private loans, or for stable high earners who are certain they will never need those protections.</p>

How much does paying an extra $100 a month save on a $35,000 loan at 6%?

An extra $100 a month on $35,000 at 6% saves about $3,188 in interest and pays the loan off roughly 31 months early. <p>The standard 10-year payment is about $388.57 ($11,629 total interest). Paying $488.57 instead clears the balance in about 89 months (7.4 years) with roughly $8,441 in interest. There is no prepayment penalty on federal or most private student loans, so every extra dollar goes straight to principal - just tell your servicer to apply it to the principal of your highest-rate loan.</p>

What is the monthly payment on a $40,000 student loan at 7% over 10 years?

A $40,000 loan at 7% over 10 years runs about $464.43 a month with roughly $15,732 in total interest. <p>That means you repay about $55,732 in all. The math is the standard amortization formula: payment = P x r / (1 - (1 + r)^-n), where r is 0.07/12 and n is 120. Stretching to 20 years lowers the payment but more than doubles interest. Test other terms in the <a href="/student-loan-calculator/">student loan calculator</a>.</p>

How much extra does a 20-year term cost versus 10 years on a $30,000 loan at 6%?

Choosing 20 years over 10 on $30,000 at 6% costs about $11,616 in extra interest. <p>Ten years means about $333.06/month and $9,967 total interest. Twenty years drops the payment to about $214.93 but raises interest to roughly $21,583. The lower payment is tempting for cash flow, but you pay more than double the interest. For federal loans, IDR is usually a smarter way to lower a payment than an extended fixed term, because IDR can end in forgiveness while a long fixed term cannot.</p>

How do I calculate a student loan payment in Excel?

Use =PMT(rate/12, years*12, -balance) to get the monthly payment in Excel. <p>For $30,000 at 6% over 10 years, enter =PMT(0.06/12, 120, -30000), which returns about $333.06. The balance is negative so the result shows as a positive payment. For total interest, multiply the payment by the number of months and subtract the principal: $333.06 x 120 - $30,000 = about $9,967. This matches our <a href="/student-loan-calculator/">student loan calculator</a>.</p>

How do I figure my first month's interest on a $28,000 loan at 6.53% by hand?

Multiply the balance by the rate and divide by 12: about $152.37 the first month. <p>$28,000 x 6.53% = $1,828.40 per year; divided by 12 that is about $152.37. Student loan interest is typically calculated daily (balance x rate / 365 x days), so the exact figure varies slightly by days in the month, but monthly division is close. Whatever your payment, this $152.37 is subtracted first and the rest reduces principal.</p>

How much does an unsubsidized loan accrue while I'm in school for 4 years?

A $20,000 unsubsidized loan at 6% accrues roughly $5,400 over 4 years of school plus a 6-month grace period. <p>Interest is about $20,000 x 6% = $1,200 per year, so 4.5 years adds around $5,400 before repayment begins. If it capitalizes, your starting balance jumps to about $25,400. A subsidized loan accrues $0 in school because the government covers the interest. This is the single biggest reason to favor subsidized over unsubsidized borrowing where you have the choice.</p>

Does Public Service Loan Forgiveness (PSLF) make refinancing a bad idea?

Yes - refinancing federal loans destroys PSLF eligibility, so pursue forgiveness first if you qualify. <p>PSLF can forgive your remaining federal balance after roughly 120 qualifying monthly payments while you work full-time for a qualifying government or nonprofit employer, and the forgiven amount is generally not taxed. Refinancing converts federal loans to private, which are not eligible. If you are on a PSLF track, a lower private rate is rarely worth giving up potential tax-free forgiveness of the entire balance.</p>

What's the monthly payment on a $60,000 loan at 7.5% over 10 versus 15 years?

A $60,000 loan at 7.5% is about $712.21/month over 10 years or $556.21/month over 15 years. <p>Ten years costs roughly $25,465 in interest; 15 years drops the payment by about $156/month but raises interest to about $40,117 - roughly $14,652 more. The longer term eases monthly strain but is expensive. If you can handle the higher payment, the 10-year plan saves a large amount. Compare both in the <a href="/student-loan-calculator/">student loan calculator</a>.</p>

Should I pay off student loans early or invest instead?

Pay extra on the loan when its rate beats your expected after-tax investment return; otherwise invest. <p>A 7% loan prepaid is a guaranteed 7% return. On $35,000 at 6%, an extra $100/month saves about $3,188 risk-free. Investing might earn more long term but is uncertain. Most people prioritize any loan above roughly 6-7%, keep an emergency fund, and capture any employer 401(k) match first. One student-loan caveat: if you are pursuing PSLF or IDR forgiveness, prepaying federal loans can be counterproductive. Compare paths with the <a href="/investment-calculator/">investment calculator</a>.</p>

Are biweekly payments worth it on a $30,000 loan at 6%?

Paying half your monthly amount every two weeks on $30,000 at 6% saves roughly $1,150 and clears the loan about a year early. <p>The 10-year payment is about $333.06, so half is $166.53 every two weeks. Twenty-six half-payments equal 13 monthly payments a year - an extra month annually. That cuts payoff to roughly 9 years and lowers interest from about $9,967 to about $8,800. You get the same benefit by simply paying about $28 extra each month directly to principal; never pay a third party to set this up.</p>

How much interest does a $100,000 graduate loan at 7% cost over 10 years?

A $100,000 loan at 7% over 10 years costs about $39,330 in interest, with a $1,161.08 monthly payment. <p>Total repaid is about $139,330. Large grad-school balances are where rate and term matter most: dropping to 6% would save roughly $6,100 in interest, and a 20-year term would nearly double the interest. Run your exact numbers in the <a href="/student-loan-calculator/">student loan calculator</a> and prioritize the highest-rate loans for any extra payments.</p>

Is a 6.8% private student loan rate good in 2026?

A 6.8% private student loan rate is roughly mid-pack - fine for strong credit, but worth comparing against federal options first. <p>On $45,000 over 10 years, 6.8% means about $517.86/month and roughly $17,143 in interest. Federal loans set rates yearly and add IDR, deferment, and forgiveness that private loans lack, so compare protections, not just the headline rate. Whether a private rate is good depends on your credit and cosigner; always get multiple quotes before committing, and exhaust federal eligibility first.</p>

Guides & articles

• How to Pay Off Student Loans Faster: 7 Strategies
• Federal vs Private Student Loans: Repayment Plans, IDR, and Forgiveness
• Student Loan Interest: Grace Period, Capitalization, and the Refinance Trade-Off

Related calculators

Mortgage Calculator · Loan Calculator · Auto Loan Calculator · Home Equity Loan Calculator · Business Loan Calculator · Boat Loan Calculator