Enter a loan's principal, rate, and term, then choose a payment frequency to calculate the fixed payment amount, total paid, and total interest.
How to Use the Loan Payment Calculator
Fill in the principal, annual rate, and term, then pick Monthly, Biweekly, or Weekly from the frequency dropdown — the payment card relabels itself to match, and total paid and total interest recalculate for whichever schedule is selected.
A loan's rate and term don't fully determine what you owe each cycle — how often you pay matters too. This calculator isolates that variable: same principal, same rate, same term, three different payment schedules, so you can see what changing the frequency actually does to the numbers.
One Formula, Three Period Counts
r = (annual rate ÷ 100) ÷ payments per year
n = years × payments per year
Payment = P × r(1+r)ⁿ ÷ [(1+r)ⁿ − 1]Switching frequency changes r and n together — a biweekly loan runs 26 shorter periods a year instead of 12 monthly ones, each with a proportionally smaller periodic rate. The underlying math is identical to a standard monthly loan; only the period count changes.
Why More-Frequent Payments Shave Off Interest
Paying biweekly instead of monthly means the balance gets chipped away slightly more often, so a little less interest accrues between each payment. Over a full term that adds up — not dramatically, but it's a real, if modest, reduction in total interest for the same rate and roughly the same amount of money paid out overall.
Weekly schedules push this further still, at the cost of a payment amount that's smaller per cycle but adds up across more cycles a year. None of the three schedules changes the loan's rate or principal — they just slice the same repayment differently.
Run the $15,000, 6.5%, four-year defaults through both schedules and the difference is real but modest: switching from monthly to biweekly payments cuts total interest by less than $20 here, since the effective annual rate barely changes — just how often it gets charged.
What to Watch For
Biweekly and weekly figures assume payments land exactly on schedule every period — 26 or 52 times a year, without skips. Real-world billing systems sometimes process "biweekly" as twice a month instead (24 payments, not 26), which is a meaningfully different schedule — check how your specific lender counts payments before comparing this against a real payoff quote.
Frequency is a minor lever next to term length: switching from monthly to biweekly on the same loan saves real money, but nowhere near as much as shortening the term by a year or two would. Use this calculator to compare frequencies at a fixed term, and the Loan Interest Calculator to see what term length alone does to the total.