Loan Calculator
Calculate your fixed loan payment, total payments, and total interest for monthly, biweekly, or weekly payment schedules.
How It's Calculated
Formula
\text{Payment} = \dfrac{P \times r \times (1 + r)^n}{(1 + r)^n - 1}This calculator works out the fixed payment for a fully-amortizing loan — one where equal periodic payments pay off both principal and interest by the end of the term, exactly like a typical personal loan. Enter the loan amount, the annual interest rate, the term, and how often you'll pay (monthly, biweekly, or weekly), and it returns your periodic payment plus the total you'll pay over the life of the loan. The same amortization mechanics conceptually apply to other fixed-rate amortizing loans, such as mortgages or auto loans, though this calculator is scoped to general personal-loan-style inputs.
Worked Examples
Monthly payments: $20,000 loan, 7.5% annual rate, 5-year term
- paymentsPerYear = 12 (monthly), so n = 5 × 12 = 60 payments
- periodicRate r = 0.075 / 12 = 0.00625
- Payment = 20000 × 0.00625 × (1.00625)^60 / ((1.00625)^60 − 1) ≈ $400.76
- Total of all payments ≈ 60 × $400.76 ≈ $24,045.54; total interest ≈ $4,045.54
Biweekly payments: $15,000 loan, 6% annual rate, 3-year term
- paymentsPerYear = 26 (biweekly), so n = 3 × 26 = 78 payments
- periodicRate r = 0.06 / 26 ≈ 0.0023077
- Payment = 15000 × r × (1 + r)^78 / ((1 + r)^78 − 1) ≈ $210.36
- Total of all payments ≈ 78 × $210.36 ≈ $16,407.73; total interest ≈ $1,407.73
Frequently Asked Questions
Why does my biweekly payment look smaller than half my monthly payment would be?
It's not just half — a biweekly schedule makes 26 payments a year, not 24 (there are slightly more than 52 weeks in a year, so 26 fortnights). Making more, smaller payments more often also means principal gets paid down faster and less interest accrues between payments, so the biweekly periodic payment ends up smaller than simply dividing the monthly payment by two, and the loan can pay off with somewhat less total interest.
Can I use this for a mortgage or auto loan instead of a personal loan?
The underlying fixed-rate amortization math is the same one used for mortgages and auto loans, so the numbers this calculator produces are mechanically correct for any fully-amortizing fixed-rate loan. This tool doesn't add mortgage- or auto-specific extras like property tax, PMI, or trade-in value — for those, use the dedicated Mortgage or Auto Loan calculators.
What interest rate should I enter?
Enter the loan's nominal annual interest rate as your lender states it (e.g. 7.5 for 7.5%) — not your APR if it bundles in fees, and not a rate already divided down to a per-payment rate. This calculator converts the annual rate to a per-period rate internally based on your chosen payment frequency.
Does changing the payment frequency change the interest rate I'm charged?
No. The annual rate you enter stays the same; only how often it's applied changes. Paying more frequently means interest compounds against a lower balance more often, which is why more frequent payments modestly reduce total interest paid, even though the annual rate is unchanged.