ARM Calculator
See how an adjustable-rate mortgage’s payment could change after the intro period, using the loan’s rate caps.
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Worst-case maximum payment
- Initial payment
- First adjustment (worst case)
- Maximum payment (worst case)
- If the fully indexed rate stays the same
- Worst-case rate path
- Caps
- Work
Saved Calculations
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How ARM Payments Adjust
An ARM has a fixed rate for the intro period, then resets to the index plus a margin, limited by caps. "2/1/5" caps mean the first reset can move at most 2 points, later resets 1 point each, and the rate can never go more than 5 points above the start.
New payment = PMT(new rate, months left, balance at reset)
Worked Example
Tips
A "5/6 ARM" is fixed for 5 years, then adjusts every 6 months; a "7/1" adjusts yearly after 7 years. Rates can also fall, but most loans have a floor. The worst case assumes the index rises enough to hit every cap. Check your loan estimate for the exact caps, margin and index (often SOFR).