Student Loan Payment Calculator: Compare Loan Costs

This student loan comparison calculator estimates the monthly payment and total interest for one fixed-rate loan using its balance, annual percentage rate (APR), and term. Enter the figures from a loan disclosure or use the defaults for an illustration; the results show the scheduled payment and interest over the full term.

Formula

The calculator uses the standard amortizing-loan payment formula. It assumes equal monthly payments, a fixed APR, and a term expressed in whole monthly payment periods.

• Monthly payment: M = round(P × r / [1 − (1 + r)⁻ⁿ], 2)
• Total interest: I = M × n − P
• Monthly rate: r = APR / 1,200
• Number of payments: n = term in years × 12

P is the loan principal in dollars, APR is the annual percentage rate entered as a percentage, r is the monthly rate as a decimal, n is the number of monthly payments, M is the monthly payment in dollars rounded to cents, and I is estimated total interest in dollars. The total-interest result uses the rounded payment, so it reflects the scheduled payment displayed by the calculator.

Worked Example

Using the defaults—$20,000 principal, 8% APR, and a five-year term:

1. Convert the APR to a monthly rate: 8 / 1,200 = 0.0066667.
2. Find the number of payments: 5 × 12 = 60.
3. Substitute into the payment formula: $20,000 × 0.0066667 / [1 − (1.0066667)⁻⁶⁰] = $405.53 per month, rounded to cents.
4. Calculate total interest using the rounded payment: $405.53 × 60 − $20,000 = $4,331.80.

These are estimates for the stated inputs and assumptions. A real repayment schedule can differ if the rate changes, fees are financed, payment dates vary, or the lender rounds payments differently.

Assumptions

• The interest rate is fixed for the entire term.
• Payments are equal, made monthly, and begin on schedule; the first payment is not treated as an upfront payment.
• Interest compounds monthly at APR / 12.
• Fees, taxes, insurance, deferment, grace periods, extra payments, and payment-plan adjustments are not included.

How to Compare Student Loans

For a useful comparison, calculate each loan separately using the amount actually borrowed, the disclosed APR, and the repayment term being considered. Keep the amounts and terms consistent when comparing rates; changing the term changes both the payment and the overall interest. The result is a mathematical comparison, not a recommendation about which loan to take.

Student financing can involve more than one loan. For example, someone borrowing $12,000 for tuition and $8,000 for living costs may have separate loans with different rates or terms. Combining those balances in this calculator and entering one blended APR would only be accurate if the loans truly share the same applicable rate and repayment schedule. Otherwise, calculate each loan on its own and add the payments and interest totals for an approximate combined view.

• Use the principal that will actually be borrowed, not the school’s full published cost if grants, savings, or other funds cover part of it.
• Check whether the quoted rate is fixed or variable and whether the APR includes charges relevant to that offer.
• Compare repayment periods directly: a longer term generally lowers the scheduled payment but can increase total interest when the rate and principal stay the same.
• Read the lender’s repayment schedule and disclosures for fees, payment dates, rate changes, and other terms the calculator cannot model.

Reading the Results and Common Mistakes

The monthly payment is the calculated amount needed for the modeled schedule, not a measure of what a student can afford or will be approved to borrow. Total interest is the estimated interest paid across all scheduled payments, not the amount of the original loan. The principal plus this interest equals the modeled total of payments.

A common mistake is entering an APR such as 8 as 0.08. The input expects a percentage, so enter 8 for 8% APR. Another is comparing a short-term loan with a long-term loan by looking only at the monthly payment. A lower payment can accompany a larger interest total because the debt remains outstanding longer. Also, rounding each payment to cents means a lender may adjust the final installment slightly to clear the remaining balance.

If a loan has a variable rate, an introductory rate, deferred interest, or unusual payment timing, one fixed-rate calculation cannot represent the full schedule. A zero or negative rate is also outside this calculator’s input range; use a suitable zero-interest calculation separately if needed. The stated APR and term should come from the lender’s current documents rather than an assumed market figure.

Alternatives and Other Costs

Scholarships, grants, savings, and work income can reduce the amount that needs to be borrowed, but they are not loans and cannot be compared through an amortization formula. A school’s financial-aid offer and each loan’s disclosure may list different cost components; make sure you distinguish the amount paid toward education from amounts borrowed and any charges that are added to principal.

Do not treat this calculator as a complete student budget or a prediction of future repayment options. It does not model school enrollment periods, pauses in repayment, income-based payments, forgiveness, eligibility, tax effects, or program rules. For those details, consult the applicable program information or loan servicer; this calculator only performs general payment arithmetic.

Frequently Asked Questions

How do I compare two student loans?
Run the calculation separately for each loan using its own principal, APR, and term. Compare both monthly payment and total interest, then check the disclosures for fees, rate variability, and other terms not represented here.

Does a longer student loan term lower the total cost?
Not necessarily. With the same principal and rate, a longer term usually reduces each scheduled payment but increases the time interest accrues, which can raise total interest.

Should I enter the interest rate or APR?
Enter the annual percentage rate as a percentage, such as 8 for 8%. The calculator converts it to a monthly rate by dividing by 1,200; use the figure and definition supplied in the loan documents.

Does this calculator include fees or changing rates?
No. It models a fixed APR and excludes fees, variable-rate changes, and other charges. Check the lender’s disclosure for the complete cost and repayment terms.

Can I combine several student loans in one calculation?
Only as a rough estimate when the loans have the same rate and repayment term. If their rates, balances, or terms differ, calculate each separately and add the resulting payments and interest.

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

Related

• Home Loan Comparison Calculator: Compare Payments
• Home Loan Comparison Rate Calculator: What It Shows
• Home Loan Comparison Calculator: Compare Payments and Cost

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