Loan Calculator
Calculate the monthly payment, total interest, and full amortization for any loan — and see how much an extra monthly payment saves.
Comment utiliser cette calculatrice
- 1Enter the total amount you are borrowing, including any fees rolled into the loan.
- 2Enter the APR from the loan offer, not the advertised headline rate.
- 3Set the term in years.
- 4Add an extra monthly payment to see how much interest and time it saves.
Comment ça marche
Amortizing loan payment
M = P × i × (1 + i)ⁿ / ((1 + i)ⁿ − 1) P = loan amount (price − down payment) i = annual rate ÷ 12 n = years × 12 Extra payments reduce the balance directly, so all their future interest is saved
The payment is set so that the balance reaches exactly zero after n months while interest accrues on whatever remains each month. Early payments are mostly interest because the balance is largest then. An extra payment goes entirely to principal, which removes that amount from every future interest calculation — which is why a small extra payment early saves far more than the same amount paid late.
Exemple détaillé
A $32,000 auto loan at 7.5% over 5 years costs $641.24 a month and $6,474 in total interest. Adding $100 a month clears it 9 months early and saves about $1,027 in interest.
Loan Calculator : le guide complet
Why the term matters more than the payment
Dealers and lenders quote monthly payments because a longer term makes any loan look affordable. Stretching a $32,000 auto loan from 5 years to 7 drops the payment from $641 to $492 — but total interest rises from about $6,474 to $9,325.
There is a second cost on cars specifically: a long term keeps you underwater. A vehicle depreciates fastest in its first three years, so on a 7-year loan you can owe more than the car is worth well into year four. If it is written off or you need to sell, the gap comes out of your pocket.
Run both terms through the calculator above and compare the total interest line rather than the monthly payment line — that is the number that tells you what the loan actually costs you.
What an extra payment actually buys
An extra payment applies entirely to principal, so it removes that balance from every remaining month's interest calculation. The saving compounds — which is why $100 a month on a 5-year loan can save over $1,000 in interest and nine months of payments.
Timing matters enormously. The same total extra paid in year one saves far more than paid in year four, because it eliminates more months of interest. If you are going to make one lump-sum extra payment, make it as early as possible.
Confirm with the lender that extra payments are applied to principal rather than prepaying the next instalment, and check for prepayment penalties — rare on auto loans in most states, more common on some personal loans.
APR is the number to compare
The interest rate alone omits origination fees, documentation fees, and any points. APR folds those into a single annualised figure, which is why it is the only fair basis for comparing two offers — and why the Truth in Lending Act requires lenders to disclose it.
For an auto loan, get pre-approved by a bank or credit union before visiting a dealer. That gives you a real APR to compare against dealer financing, and it converts you into a cash buyer in the negotiation, which separates the price conversation from the financing conversation.
Questions fréquentes
What is a good interest rate on a car loan?
It depends heavily on credit score and whether the car is new or used. Borrowers with excellent credit typically see the lowest advertised rates, while subprime borrowers can pay several times more. Used-car rates run 2–4 percentage points above new-car rates. Always compare a credit union quote against dealer financing.
Should I make a larger down payment?
It reduces the amount financed, which lowers both the payment and the total interest, and it protects against being underwater. A common guideline for cars is 20% down on new and 10% on used. The exception is a genuine 0% promotional rate, where there is no interest cost to reduce.
Does paying extra reduce my monthly payment?
No — it shortens the loan instead. The scheduled payment stays the same and you simply finish earlier. Some lenders offer re-amortisation, which recalculates a lower payment over the original term after a large principal reduction, but you have to ask for it.
Can I use this for a mortgage?
The maths is identical, but the mortgage calculator adds the things a home loan needs — property tax, insurance, and PMI context. Use this one for auto, personal, and student loans where principal and interest are the whole payment.