Mortgage calculator
Change any input and instantly see your monthly payment, total interest, and how two repayment methods compare.
Enter a loan amount and term greater than 0.
- Interest-only payment
- —
- Total interest
- —
- Total paid
- —
Compare the two methods
| Equal payment | Equal principal | |
|---|---|---|
| Monthly payment | — | — |
| Total interest | — | — |
| Total paid | — | — |
Yearly payments: principal and interest
Amortization schedule
| Period | Principal | Interest | Payment | Balance |
|---|
| Period | Principal | Interest | Payment | Balance |
|---|
How to use this calculator
- Enter the loan amount, annual interest rate and loan term.
- Choose a repayment method: equal payment or equal principal.
- If your loan starts with an interest-only period, enter the number of months; otherwise enter 0.
- Results update instantly. The comparison below calculates the other method too, and the schedule can be expanded to show every month.
Your inputs are saved in the page address, so you can copy the URL to share or bookmark the exact calculation.
Equal payment vs equal principal
| Equal payment | Equal principal | |
|---|---|---|
| Monthly payment | The same every month | Highest at first, then decreases |
| Principal per payment | Small at first, larger later | The same every month |
| Total interest | Higher | Lower |
| Early-year burden | Lower | Higher |
| Good for | A predictable monthly budget | Strong early income and minimizing interest |
Why does equal principal cost less interest? It pays down more principal from the start, so the balance falls faster and each later month’s interest is calculated on a smaller amount. The trade-off is higher payments in the early years.
Most mortgages, including standard US fixed-rate loans, use equal payments. Equal principal is more common in some Asian markets; ask your lender whether it’s available.
Interest-only periods: pros and cons
During an interest-only period you pay interest but no principal, so early payments are low — helpful if cash is tight right after buying or you expect your income to grow.
Two things to keep in mind:
- Payments jump when the period ends, because the same principal must be repaid over fewer months.
- You pay more interest overall, because the principal stays outstanding longer.
Try setting the period to 0 and then 36 months to see the difference in total interest.
Is paying off early worth it?
Paying down principal early reduces the interest on every later payment, so it usually saves a lot. Things to weigh:
- Whether your lender charges a prepayment penalty
- Whether investing the money might earn more than your mortgage rate
- Whether you’d still have a healthy emergency fund
This calculator doesn’t model extra payments yet.
Frequently asked questions
Will the results match my lender’s numbers?
It uses the standard method: each month’s interest is the remaining balance × annual rate ÷ 12, rounded to the cent, with the final payment absorbing any rounding difference. Day-count conventions, rate changes, taxes, insurance and fees can make real payments differ — rely on your lender’s official documents.
What about variable rates?
The calculator assumes one rate for the whole term. To see the effect of a rate rise, increase the rate and compare.
Is my data sent anywhere?
No. Everything is calculated in your browser; we never receive the numbers you enter.