10/1 ARM Calculator — Adjustable-Rate Mortgage
A 10/1 ARM locks in a fixed rate for the first 10 years, then resets annually. Enter your loan details, the expected adjusted rate, and the per-adjustment cap to see both periods' payments, the balance at reset, and the full balance curve.
$
%
%
years
%
Payment for the first 10 years at the initial fixed rate
- 1
Monthly interest rate
r = 5.75% ÷ 12 ÷ 100 = 0.004792 - 2
Number of payments
n = 30 × 12 = 360 - 3
Growth factor
(1+r)ⁿ = 1.004792ⁿ = 5.5894How much one unit of principal grows over the full term at the monthly rate. - 4
Fixed-period monthly payment
300,000 × 0.004792 × 5.5894 ÷ (5.5894 − 1) = 1,750.72
How does this calculator work?
A 10/1 ARM holds a fixed rate for 10 years, then resets annually capped at a per-adjustment limit (often 2%). Payments for both periods are calculated with standard amortisation — initial PMT over the full term, adjusted PMT over the remaining term on the outstanding balance. Compare both to judge the rate-risk trade-off.
Formula
How this is calculated
A 10/1 hybrid ARM (Adjustable-Rate Mortgage) has two phases. During the first 120 months (10 years), the interest rate is fixed — the payment is calculated using the standard amortisation formula applied over the full loan term. After month 120, the rate resets annually based on a benchmark index (commonly the SOFR or one-year Treasury) plus a lender margin.
At the first adjustment, the new rate is subject to a per-adjustment cap (typically 2 percentage points above the initial rate). This calculator applies that cap to your expected rate so the displayed payment reflects the worst-case scenario allowed at the first reset. The remaining balance at the end of the fixed period is recast — recalculated using the new rate and the remaining term — to determine the adjusted monthly payment.
ARM rates, caps, and index margins vary by lender and are specified in the loan note. The lifetime cap (typically 5–6% above the start rate) is not applied here. This tool shows one rate-adjustment scenario; a full ARM assessment should model multiple future index paths. Values are illustrative estimates for 2025 US market conditions — consult your lender for your actual note terms.
Frequently asked questions
Borrowers who expect to sell or refinance within 10 years often benefit from a 10/1 ARM: the initial fixed rate is typically 0.25–0.75% lower than a 30-year fixed, reducing payments during the period they plan to hold the loan. The risk is carrying the loan into the variable period if plans change.
A per-adjustment (or periodic) cap limits how much the interest rate can change at any single annual reset — most commonly 2%. So if your start rate is 6%, the first adjusted rate cannot exceed 8% regardless of where the index moves. A lifetime cap (often 5–6% above start) further limits total exposure.
The outstanding balance at the end of year 10 is treated as a new loan and recast over the remaining term (e.g. 20 years for a 30-year mortgage) at the new rate, using the same amortisation formula. This is why the payment can jump significantly if rates have risen.
Also known as
TG we-Calculate Editorial Team. (2026). 10/1 ARM Calculator — Adjustable-Rate Mortgage [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/10-1-arm-calculator
TG we-Calculate Editorial Team. "10/1 ARM Calculator — Adjustable-Rate Mortgage." TG we-Calculate. 2026. https://we-calculate.com/calculator/10-1-arm-calculator.
TG we-Calculate Editorial Team, "10/1 ARM Calculator — Adjustable-Rate Mortgage," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/10-1-arm-calculator
@misc{wecalculate_10_1_arm_calculator, title = {10/1 ARM Calculator — Adjustable-Rate Mortgage}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/10-1-arm-calculator}}, year = {2026}, note = {TG we-Calculate} }
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