How it works it out
A fixed-rate mortgage follows a schedule set on the day it closes: the same payment every month, split between interest on what you still owe and principal. The calculator rebuilds that schedule from the amount you borrowed, the rate and the term, and counts the payments due between your first payment and today. What you owe is the balance after the latest of them. It uses your device's date, so it's always current.
You'll find the numbers it needs on your closing documents or an early statement: the original loan amount (not the home's price), the interest rate, the term and the date of the first payment. Your monthly payment doesn't need entering. It follows from the others, and matching it against your statement's principal and interest is a good check that you entered them right.
An example
Take a $320,000, 30-year loan at 3.25% whose first payment was in January 2021. The payment is $1,392.66 a month in principal and interest.
- In January 2026, after 61 payments, the balance is $285,162.97. Of about $85,000 paid so far, $34,837.03 went to principal and $50,115.23 to interest. There are 299 payments left, the last in December 2050, with $131,242.48 of interest still to come.
- In January 2031, after 121 payments, it's $244,806.68. Early on, most of each payment is interest, so the balance falls slowly at first and faster later.
- With $200 extra every month from the start, the balance in January 2026 is $271,916.77, and the loan ends in March 2045, 5 years and 9 months early, with $93,547.76 of interest left instead of $131,242.48.
- With one $10,000 extra payment in June 2023, the January 2026 balance is $274,288.37, and the last payment moves to July 2049.
- If the home is worth $450,000, the January 2026 balance leaves about $164,800 of equity, 37% of its value.
If your rate has changed
An adjustable-rate mortgage (ARM) keeps its first rate for a few years, then adjusts. Under “Rate changes”, enter the month each new rate took effect and the rate itself; your statements or the lender's rate-change notices show both. At each change the payment is worked out again on what you owe then, over the time left, which is what lenders do.
Say the same loan were a 5/6 ARM that moved to 5.25% in January 2026 and to 6.25% in July 2026. The payment rises from $1,392.66 to $1,712.54, then to $1,882.60. By September 2026 you'd owe $281,744.96 instead of $280,152.93 at the original rate, with $266,095.14 of interest still to come instead of $125,111.24, if the rate stays at 6.25%. Enter a new change when your rate moves again.
The same section works for a loan modification that changed the rate. Payments can be monthly, twice a month or every two weeks; biweekly loans are fixed-rate here.
Why your payoff amount is different
The balance here is the one on your loan's schedule after this month's payment. If you want to pay the loan off, sell or refinance, your servicer will give you a payoff amount, which is usually a little higher: interest keeps building day by day between payments, so the payoff adds interest up to the day it's paid, plus any fees due. The CFPB explains how a payoff amount differs from your balance. The calculator estimates it under “To pay it off”, for any day you choose, and the mortgage payoff amount calculator explains how it's worked out. Ask your servicer for a payoff statement for the exact figure.
The schedule's balance can also differ from your statement's if:
- a payment was late, partial or made on a different day;
- you paid extra that isn't entered here, or the servicer applied it differently;
- your loan was modified, or its rate changed, and the changes aren't entered here;
- the loan was refinanced, which starts a new schedule: enter the new loan instead.
What to do with the number
- Pay it off sooner: the payoff calculator finds the extra each month to be done by a date you choose.
- Refinance: enter what you owe and the time left in the refinance calculator to see if a new rate pays off.
- Borrow against your equity: the HELOC calculator starts from what you owe and what the home is worth.
- See every payment: the link under the results opens your loan in the mortgage calculator, with a date on every row and this month's payment marked.
Common questions
Why is so little of my payment going to principal?
Interest each month is charged on the whole balance, which is largest at the start. As the balance falls, the interest share shrinks and the principal share grows, though the payment stays the same.
Does it work for an adjustable-rate loan?
Yes. Enter each rate change under “Rate changes”, as above. To see where the rate could go next, the ARM calculator models the caps and the best and worst cases.
My escrow payment is in my statement. Should I include it?
No. Property tax and insurance paid through escrow don't reduce what you owe. Enter only the loan's own terms.
Is my information stored anywhere?
No. The calculation runs in your browser, and nothing you enter is sent anywhere. See the privacy page.