10/1 ARM Calculator

Estimate your monthly payment during the 10-year fixed period, the principal balance left when the rate first adjusts, and the new payment at your expected adjusted rate.

Quick Facts

Formula
Standard amortization: M = P × r(1+r)^n / ((1+r)^n − 1)
Rate is fixed for 120 months; the remaining balance is then re-amortized over the rest of the term at the adjusted rate.

Your Results

Calculated
Initial monthly payment
-
Principal & interest, years 1–10
Balance after 10 years
-
Principal owed at first adjustment
Adjusted monthly payment
-
Year 11 on, at the expected rate
Total interest paid
-
Full term, if adjusted rate holds

Ready

Enter your loan details, then press Calculate.

How the 10/1 ARM calculation works

A 10/1 adjustable-rate mortgage keeps its interest rate fixed for the first 10 years (120 monthly payments), after which the rate resets once every year for the rest of the term. This calculator runs the standard amortization math in three steps:

  • Initial payment: M = P × r(1+r)n / ((1+r)n − 1), where P is the loan amount, r is the initial monthly rate (APR ÷ 12), and n is the total number of payments (term × 12).
  • Balance at first adjustment: after 120 payments the remaining principal is B = P(1+r)120 − M × ((1+r)120 − 1) / r.
  • Adjusted payment: B is re-amortized over the remaining months at your expected adjusted rate, giving the payment from year 11 to payoff.

Assumptions to keep in mind

The projection assumes the adjusted rate you enter stays constant from the first reset to payoff. A real 10/1 ARM adjusts every year after year 10, moving with its index plus a fixed margin and limited by initial, periodic, and lifetime rate caps. Results cover principal and interest only — property taxes, homeowners insurance, PMI, and HOA dues are excluded.

Interpreting the output

Compare the initial and adjusted payments to see your exposure at the first reset, and enter your loan's lifetime-cap rate as the adjusted rate to see the worst-case payment. If you expect to sell or refinance within 10 years, the initial payment and the 10-year balance are the numbers that matter most, and the discounted initial rate versus a comparable 30-year fixed is the trade-off to weigh. For a major loan decision, verify figures against your official loan estimate or a licensed professional.

Frequently Asked Questions

What does the 10/1 in a 10/1 ARM mean?
The 10 is the number of years the initial interest rate stays fixed; the 1 means the rate can then adjust once every year for the rest of the term. On a 30-year 10/1 ARM you make 120 payments at the fixed rate, followed by 20 years of annually adjusting rates.
How is the payment after the first adjustment calculated?
The remaining balance after 120 payments is re-amortized over the remaining term at the new rate using the standard formula M = B × r(1+r)^m / ((1+r)^m − 1), where B is the balance, r is the new monthly rate, and m is the number of months left. This calculator assumes the adjusted rate you enter holds from year 11 to payoff.
Do rate caps limit how much a 10/1 ARM can adjust?
Yes. Most ARMs carry three caps: an initial adjustment cap, a periodic cap on each later adjustment, and a lifetime cap above the start rate (a common structure is 5/2/5). Check your loan estimate for the exact caps, then enter the lifetime-cap rate here to see your worst-case payment.

Related finance calculators

Mortgage Calculator Loan Calculator Compound Interest Calculator Savings Calculator ROI Calculator