🏦 Loan & Mortgage Calculator
Work out the fixed monthly payment for any amortizing loan — mortgage, auto loan, personal loan or student loan. Everything is calculated instantly in your browser; nothing is sent anywhere.
One formula, then a simulated payoff
The required payment on any amortizing loan comes from the standard formula,
with P the amount borrowed, r the monthly rate (annual
rate / 12) and n the number of monthly payments:
Payment = P x r x (1 + r)^n / ((1 + r)^n - 1)$300,000 at 6.5% over 30 years works out at $1,896.20 a month. The extra payment box is not part of that formula, so the tool runs the balance forward month by month instead: interest is charged, everything else comes off the principal, and it counts how many months pass before the balance hits zero.
What an extra payment actually buys
Extra money goes entirely to principal, so it removes all the future interest that principal would have generated. On the same $300,000 loan:
| Extra per month | Payoff | Total interest |
|---|---|---|
| $0 | 30 years | $382,633 |
| $100 | 26 years | $321,639 |
| $200 | 23y 1mo | $279,185 |
| $500 | 17y 6mo | $202,874 |
The first $100 is worth $60,995. The return is best early, because that is when the principal you retire has the longest left to run.
Frequently asked questions
How much does one percent on the rate cost?
On $300,000 over 30 years, going from 5.5% to 6.5% raises the payment from $1,703.37 to $1,896.20 and total interest from $313,212 to $382,633. Each percentage point is about $193 a month here.
Does the extra payment box change my required payment?
No. The scheduled payment stays $1,896.20 and the extra sits on top, so skipping it in a tight month is not a missed payment. It only shortens the term.
Can I use this for a car or student loan?
Yes - any fixed-rate loan with equal monthly payments uses this same formula. Enter the term in years, so 60 months is 5. Credit cards do not fit, because their minimum payment is a shrinking percentage of the balance rather than a level amount.