Student Loan Calculator

Calculate your monthly payment, total interest, and payoff timeline. See how extra payments save you money and shorten your debt.

Calculator

Total borrowed before interest or fees.

Check your loan documents for your rate.

Federal standard plan is 10 years.

Additional amount to pay down principal faster.

Interest accrual while in school (optional)
Loan type during school:

Subsidized loans don't accrue interest while you're in school. Unsubsidized interest accrues and adds to your principal at repayment.

Monthly payment

—
— Total interest paid
— Total amount paid
— Payoff date
— Interest as % of principal

The formula, spelled out

Here's how your monthly payment is calculated:

r = annualRate / 100 / 12
n = years × 12

If r > 0:
  M = P × r / (1 − (1+r)^−n)
If r = 0:
  M = P / n

Total paid = M × n
Total interest = Total paid − P

For unsubsidized loans accruing interest in school:
P_repay = P + P × (annualRate/100) × (monthsInSchool/12)
This uses simple interest for clarity, not daily accrual.

What each variable means:

  • P = Loan principal (amount borrowed)
  • r = Monthly interest rate (annual rate ÷ 100 ÷ 12)
  • n = Number of monthly payments
  • M = Monthly payment amount
  • P_repay = Principal at repayment (after in-school accrual)

This is the standard amortization formula used by federal and private lenders. Each month, a portion of your payment goes toward interest (calculated on your current balance) and the rest toward principal.

Federal vs. private loans: the differences that matter before you borrow

Subsidized vs. unsubsidized (federal only)

If you have a subsidized federal loan, the U.S. Department of Education pays your interest while you're in school and during your six-month grace period. You owe only the principal when repayment begins.

With an unsubsidized federal loan, interest accrues from day one, even while you're in school. If you don't pay it as you go, that unpaid interest is capitalized (added to your principal) at repayment, meaning you start owing more than you borrowed.

Fixed rates and repayment plans

Federal Direct Loans carry a fixed interest rate set by Congress, which means your rate never changes. You cannot refinance to a lower federal rate, but you also won't face rate hikes. Federal loans also offer multiple repayment plans, including income-driven plans where your payment can be as low as $0 per month if your income qualifies.

Private student loans typically have variable or fixed rates set by lenders, and they usually don't offer income-driven repayment or public service loan forgiveness.

Origination fees and other costs

Federal Direct Loans charge an origination fee (a percentage deducted from your disbursement before you receive the money). This fee varies slightly by loan type; check studentaid.gov for current rates. Private lenders may charge additional fees like application fees or late fees.

Forgiveness and income-driven repayment

Federal borrowers can access income-driven repayment plans, which cap monthly payments at 10–20% of discretionary income and offer forgiveness after 20–25 years of qualifying payments. Federal public service loan forgiveness cancels remaining balances after 10 years for eligible government or nonprofit employees. Private loans rarely offer either option.

Cosigner requirements

Federal Direct Loans require no cosigner. Parent PLUS loans may require credit review but not a separate cosigner. Most private loans require either a good credit score or a cosigner with strong credit to qualify.

The rule of thumb people cite about borrowing

A common heuristic in education finance circles is that you should not borrow more than your expected annual starting salary. For example, if your first-year salary after graduation will be $50,000, aim to borrow no more than $50,000 in total. This rule helps ensure your debt-to-income ratio stays manageable and you're not loan-burdened early in your career.

Of course, this is a guideline, not a hard rule. Your actual borrowing limits depend on your financial situation, your degree, and your career prospects. But it's a useful metric to keep in mind when deciding how much to borrow.

Extra payments go straight to principal and can save you years of payments and tens of thousands in interest.

Frequently asked questions

What's the difference between subsidized and unsubsidized loans?

Subsidized federal loans: the government pays your interest while you're in school and during your grace period. You only owe the principal when repayment starts.

Unsubsidized federal loans: interest accrues from the date of first disbursement. If you don't pay it while in school, the unpaid interest is capitalized (added to principal) at repayment, increasing the amount you owe.

How do extra payments help?

Every extra dollar you pay goes directly to reducing your principal. Because interest is calculated on your outstanding balance, paying down principal faster means less interest accrues each month. This compounds over time: you'll pay off your loan earlier and save a significant amount in interest.

What happens if I don't pay interest while in school?

For subsidized loans, the government covers it; you owe nothing. For unsubsidized loans, unpaid interest is capitalized, added to your principal, at the start of repayment. This increases the amount you're paying interest on, so it's generally better to pay interest as it accrues if you can.

Can I pay off my loan early without a penalty?

Federal student loans have no prepayment penalty. You can pay extra or pay off your entire balance at any time without owing an additional fee. Always make sure any extra payment is applied to principal, not future interest.

What repayment plans does the federal government offer?

Federal borrowers can choose from several plans: the Standard Plan (10 years), Graduated Plan (10 years, starting low), Extended Plan (25 years), and income-driven plans (PAYE, REPAYE, IBR, ICR) where payments are tied to your income and can be as low as $0. Check studentaid.gov for details and eligibility.

Should I use this calculator for private loans?

Yes, the basic monthly payment formula is the same for federal and private loans. However, private loans often have variable rates, different capitalization rules, and fewer repayment options, so always check your promissory note for exact terms.

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