Adjustable-Rate Mortgage Calculator
Model how an adjustable-rate mortgage payment changes when the rate resets after the fixed period.
About the Adjustable-Rate Mortgage Calculator
Enter the loan amount, the starting rate, how long it's fixed, the rate it might reset to and the term. The calculator shows the payment during the fixed period, the balance left at reset, and the new payment.
A 5/1 or 5/6 ARM has a fixed rate for 5 years, then resets periodically to an index plus a margin, within caps (often 2/1/5 or 5/1/5). Try the worst case: the initial rate plus the lifetime cap.
The formula
After reset: amortize the remaining balance over the remaining term at the new rate
Worked example
$300,000 at 5.75% fixed for 5 years, then 7.5%, over 30 years
- Years 1–5: $1,750.72 a month
- Balance at reset: $278,287
- From year 6: $2,056.51 a month, 17.5% more
Things to keep in mind
- Models one reset to a single rate; real ARMs can change every 6 or 12 months after the fixed period.
Questions people ask
What do the caps mean?
First adjustment cap / later adjustment caps / lifetime cap above the start rate.
When does an ARM make sense?
If you'll sell or refinance before the fixed period ends.
What is a 5/6 ARM?
Fixed for 5 years, then adjusting every 6 months, usually tied to SOFR.