Loan Calculator
CalculatorsCalculate the monthly payment, total interest, and total cost of a fixed-rate loan of any type.
Monthly payment
$400.76
Total interest
$4,045.54
Total paid
$24,045.54
Estimate only — assumes a fixed rate and no extra payments.
What this loan calculator does
This calculator works for any fixed-rate installment loan — auto loans, personal loans, student loans, or business loans — by computing the monthly payment, total interest paid, and total cost over the life of the loan based on the amount borrowed, the interest rate, and the term. It uses the standard amortization formula, which produces a fixed monthly payment throughout the loan, with the split between principal and interest shifting from more interest-heavy early on to more principal-heavy later.
How loan interest actually adds up
The interest rate you're quoted (the APR) applies to the outstanding balance, not the original loan amount, which is why the total interest paid over a loan's life can be a large fraction of the original amount, especially for longer terms. A $20,000 loan at a moderate rate over a short term might cost a few thousand dollars in total interest, while the exact same rate stretched over a much longer term can more than double the total interest paid — the trade-off being a lower monthly payment. This calculator makes that trade-off visible so you can compare terms side by side before committing.
Common use cases
Car buyers compare loan offers from a dealer against a bank or credit union pre-approval by checking which produces a lower total cost, not just a lower monthly payment. Borrowers compare a shorter loan term against a longer one to see the real dollar trade-off between manageable monthly payments and total interest paid. People evaluating a personal loan for debt consolidation use it to confirm the new loan actually saves money compared to what they're currently paying, and small business owners use it to estimate financing costs before taking out equipment or working capital loans.
Tips for comparing loan offers
When comparing loan offers, look at the total cost (principal plus total interest) rather than just the monthly payment — a lower monthly payment achieved by stretching out the term can end up costing significantly more overall. Also pay attention to whether a quoted rate is the interest rate or the APR; the APR typically includes certain fees and gives a more accurate picture of the loan's true cost, and plugging the APR into this calculator gives a more realistic estimate than the base interest rate alone.
Reading an amortization schedule
Behind every fixed monthly payment is an amortization schedule — a month-by-month breakdown showing how much of each payment goes to interest versus principal. Early in the loan, interest makes up a disproportionately large share of the payment because it's calculated on the full remaining balance, which is still close to the original loan amount. As the balance shrinks with each payment, the interest portion shrinks too, and more of each fixed payment goes toward paying down principal instead. Understanding this shape is useful beyond curiosity — it explains why paying off a loan a year early saves less in interest than paying it off a year early at the very start, since by the final year, most of the interest has already been paid.
How to use Loan Calculator
- 1Enter the loan amount, interest rate, and term.
- 2View the monthly payment and total interest.
- 3Adjust values to compare scenarios.
Frequently asked questions
Does this account for extra payments?
Not in Phase 1 — extra/prepayment scenarios are planned for a future update.
What types of loans can I calculate?
Any fixed-rate installment loan works — auto loans, personal loans, student loans, and business loans all use the same amortization math.
Should I use the interest rate or the APR?
The APR gives a more accurate total cost estimate since it typically includes certain fees on top of the base interest rate — use it when you have it.
Why does a longer loan term cost more in total interest?
Interest accrues on the outstanding balance over time, so stretching repayment over more months gives interest more time to add up, even at the same rate.
Is the monthly payment fixed for the whole loan term?
Yes, for a standard fixed-rate amortizing loan — the payment amount stays the same each month, though the mix of principal and interest within it shifts over time.