Loan Calculator
Use this for any fixed-rate loan: a personal loan, a student loan, a home improvement loan or a loan to a friend. Enter the amount, the rate and how long you will take to pay it back.
Then try adding a little extra each month. You will see how much interest you save and how many months sooner the loan ends.
Please note: Estimate only. This is not financial advice. Your lender’s numbers are the ones that count.
How it works
A fixed-rate loan has the same payment each month. Each payment first covers the interest that built up that month, and the rest reduces what you owe. Because you owe less each month, the interest part shrinks and the principal part grows.
The monthly payment comes from the loan formula below. The yearly table shows how much of each year went to principal and interest, and what you still owe at year end.
When you add an extra payment, it goes entirely to principal. That lowers the balance faster, so less interest is charged in every later month. This is why even small extra payments can take months or years off a loan.
If the loan has an upfront fee, such as an origination fee, enter it as a percent. It is added to the total cost, but the loan amount stays the same, because the fee is usually taken out of the money you receive.
monthly rate = yearly rate ÷ 12
payment = amount × rate ÷ (1 − (1 + rate)^−months)
total interest = payments made − amount borrowedWorked example: $20,000 at 8% for 5 years
The payment is $405.53 a month. After 60 payments you will have paid $24,331.62, which means $4,331.62 of interest.
Add $100 a month. The loan is paid off in 47 months instead of 60. Total interest falls to $3,295.25, so you save $1,036.37 and finish 13 months early.
Frequently asked questions
Does this work for any type of loan?
It works for fixed-rate loans that you pay back in equal monthly payments, such as personal loans, many student loans and car loans. It does not handle variable rates, interest-only periods or credit cards.
What is APR, and should I enter it?
APR includes the interest rate and some fees, expressed as a yearly rate. For a close total-cost picture, enter the interest rate and add fees in the fee box. Use the APR only if you do not know the rate.
Is it better to take a longer loan?
A longer loan lowers the payment but raises the total interest. A shorter loan costs less overall but needs a bigger payment. Try both terms and compare the total interest.
How do extra payments work?
Extra money goes to principal, so interest is charged on a smaller balance every month after. Check with your lender that there is no penalty for paying early, and that extra payments go to principal.
Why do the first payments mostly go to interest?
Interest is charged on what you owe, and you owe the most at the start. As the balance drops, less of each payment is interest.
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Content last reviewed 2026-10-13.