Student Loan Repayment Schedule Calculator

A student loan repayment schedule calculator estimates the fixed monthly payment, total paid, and total interest for a loan when you enter its balance, annual interest rate, and repayment term. This estimate assumes equal monthly payments and a fixed rate; it does not model income-based payments, fees, deferment, or loan-program rules.

Formula

The calculator uses the standard fixed-payment amortization formula. It first finds the payment that pays off the starting balance over the specified number of monthly periods, then totals those rounded payments.

• Monthly payment: M = round[P × r ÷ (1 − (1 + r)⁻ⁿ), 2]
• Total paid: T = M × n
• Total interest: I = T − P

P is the loan amount in dollars; APR is the annual percentage rate entered as a percentage; r is the monthly rate, APR ÷ 1,200; n is the number of monthly payments, loan term in years × 12; M is the monthly payment in dollars; T is total paid in dollars; and I is estimated interest in dollars. The payment is rounded to cents before totals are calculated, so total paid equals the displayed payment multiplied by the number of months.

Worked Example

Using the calculator’s default values—$20,000 borrowed at 8% APR for 5 years:

1. Convert the annual rate to a monthly decimal: r = 8 ÷ 1,200 = 0.0066667.
2. Find the number of payments: n = 5 × 12 = 60.
3. Substitute into the payment formula: M = round[20,000 × 0.0066667 ÷ (1 − (1.0066667)⁻⁶⁰), 2] = $405.53 per month.
4. Total paid: $405.53 × 60 = $24,331.80.
5. Total interest: $24,331.80 − $20,000 = $4,331.80.

Assumptions

• The interest rate stays fixed for the full term.
• Payments are equal, made monthly, and begin on schedule; the calculation treats them as end-of-period payments.
• Interest accrues monthly using APR ÷ 12, with no separate daily-interest adjustment.
• Fees, taxes, insurance, skipped or late payments, capitalization, and extra payments are not included.

How to Read a Repayment Schedule

A repayment schedule, often called an amortization schedule, shows how each payment is split between interest and principal. Early in a level-payment loan, more of the payment generally goes toward interest because interest is calculated on a larger outstanding balance. As principal falls, the interest portion usually decreases and more of each payment reduces the balance. The amount due remains the same under the calculator’s fixed-rate assumptions.

For the example, the first month’s estimated interest is about $133.33 ($20,000 × 0.0066667). The remaining portion of the $405.53 payment—about $272.20—reduces principal. Later rows would use the lower balance to calculate interest. Small differences can appear in a real servicer’s schedule because of payment dates, daily accrual, rounding, or account-specific adjustments.

Using the Calculator Carefully

Enter the amount that is actually being repaid, the applicable APR, and the term in years. If you have multiple loans, calculate them separately when their balances, rates, or terms differ; adding balances and using one rate can conceal important differences. Check whether a quoted rate is fixed or variable and whether the figure you have is the rate used for repayment. Use the figures supplied by the servicer or loan documents rather than treating the example default as a current or typical rate.

• Check the units: enter APR as a percentage, such as 6.5, not as 0.065. The formula converts it to a monthly decimal.
• Use the remaining term: for an existing loan, the original term may not be the number of payments left.
• Separate loans when needed: a portfolio with different rates and due dates may require a schedule for each balance.
• Expect rounding: the displayed payment is rounded to cents. Actual final payments may be adjusted to clear a small residual balance.
• Do not treat the total as a payoff quote: a payoff amount on a particular date may include interest accrued since the last payment and other account-specific amounts.

A lower monthly payment does not automatically mean less total interest: extending the repayment term increases the number of payments and can increase the total paid, all else equal. Conversely, shortening the term usually raises the calculated monthly payment while reducing the number of periods over which interest accrues. These are arithmetic effects under the stated assumptions, not a recommendation about which arrangement to choose.

What This Estimate Does Not Cover

This calculator models one fixed-rate loan with equal monthly payments. It does not determine a personalized repayment amount under a program, eligibility, forgiveness, tax treatment, or a lender’s account rules. It also does not simulate a variable interest rate, a change in payment amount, extra principal payments, periods without payments, interest capitalization, or multiple disbursements. Those features can materially change a real schedule.

For a variable-rate loan, the future rate may change, so a single fixed-rate calculation cannot forecast the complete repayment path. For payments that change with income or other conditions, the standard amortization formula may not apply. Ask the loan servicer for an account-specific payment schedule and check the relevant program information for rules that are not represented here.

Frequently Asked Questions

How do I calculate a student loan monthly payment?
Convert APR to a monthly decimal by dividing it by 1,200, convert the term to months, then use the fixed-payment formula shown above. This calculator performs those steps and rounds the payment to cents.

Does the calculator show principal and interest for every month?
It estimates the monthly payment and overall totals, not a row-by-row table. A full schedule calculates each month’s interest from the outstanding balance, subtracts the principal portion of the payment, and carries the remaining balance forward.

Why does my servicer’s amount differ?
The servicer may use a different balance, rate, remaining term, payment date, daily interest method, rounding convention, or account adjustment. Compare the inputs and ask the servicer to explain account-specific differences.

Can I use this for multiple student loans?
Use it separately for each loan when rates or repayment terms differ. You can add the resulting payments for a rough combined estimate, but account for different due dates and payment rules separately.

Does this calculate income-based payments or forgiveness?
No. It calculates general fixed-rate loan arithmetic only. It does not model repayment-program rules or forgiveness; consult the servicer or program information for applicable details.

The result is an estimate, and the lender’s disclosure gives the exact figures.

Related

• Debt Snowball Excel: Free Payoff Calculator
• Current Student Loan Repayment Options Explained
• Current Student Loan Repayment Plans Explained

in p | Loan amount | $ | 20000 | 1 | 100000000
in apr | Interest rate (APR) | % | 8 | 0.01 | 100
in yrs | Loan term | years | 5 | 0.0833 | 50
out pmt | Monthly payment | $ | round(p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)), 2) | 2
out int | Total interest | $ | pmt * yrs * 12 - p | 2
out tot | Total paid | $ | pmt * yrs * 12 | 2