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10/1 ARM Mortgage Calculator

Calculate monthly payments, interest costs, and worst-case rate adjustments for a 10/1 adjustable-rate mortgage.

Loan details

$
%
years

ARM adjustment settings

%
%
%
%
%

Initial monthly payment (years 1-10)

$1,520.06

Fixed at 4.5% for the first 10 years

Expected payment after first adjustment

$1,791.38

Adjusted rate 6.5% on $240,268.30 for 240 months

Worst-case payment (lifetime cap)

$2,239.62

Maximum rate 9.5% after year 10

Loan balance after 10 years

  • Principal repaid$59,731.7019.9%
  • Remaining balance$240,268.3080.1%

How this ARM payment is calculated

From your loan amount, fixed-rate period, and adjustment caps to the three payment scenarios.

  1. Initial payment during the fixed period

    PMT0=P×i0(1+i0)n(1+i0)n−1\mathrm{PMT}_0 = P \times \frac{i_0(1+i_0)^n}{(1+i_0)^n - 1}

    Compute the level payment at 4.5% over the full 30-year term. This is what you pay in years 1 through 10.

  2. Remaining balance after the fixed period

    B120=P×(1+i0)n−(1+i0)120(1+i0)n−1B_{120} = P \times \frac{(1+i_0)^n - (1+i_0)^{120}}{(1+i_0)^n - 1}

    After 120 months of the initial payment, the outstanding balance becomes the new principal for the adjustable years.

  3. First adjusted rate with caps

    Rate11=max⁡(R0−Ci, min⁡(R0+Ci, Index+Margin))\text{Rate}_{11} = \max(R_0 - C_i,\ \min(R_0 + C_i,\ \text{Index} + \text{Margin}))

    The fully indexed rate is index plus margin, limited by the initial cap and lifetime cap relative to the start rate.

  4. Expected and worst-case payments

    PMTadj=B120×i(1+i)n−120(1+i)n−120−1\mathrm{PMT}_{adj} = B_{120} \times \frac{i(1+i)^{n-120}}{(1+i)^{n-120} - 1}

    Recalculate the payment on the remaining balance for the adjustable years. The worst case uses the lifetime cap above the initial rate.

Report tool

What is a 10/1 ARM mortgage?

A 10/1 adjustable-rate mortgage (ARM) keeps the same interest rate for the first 10 years, then resets once per year based on a market index plus a lender margin. This calculator estimates your payment during the fixed period, the likely payment after the first adjustment, and a worst-case payment if rates hit the lifetime cap. All math runs in your browser.

Enter the loan amount, initial rate, full loan term, and ARM caps. The fixed-period payment uses the same amortizing formula as a standard home loan. If you only need a single fixed rate for the full tenure, the EMI calculator is the simpler starting point. Check whether the resulting payment fits common affordability limits with the 28/36 rule calculator.

Initial payment formula

PMT0=P×i0(1+i0)n(1+i0)n−1\mathrm{PMT}_0 = P \times \frac{i_0(1+i_0)^n}{(1+i_0)^n - 1}

P is the loan amount, i₀ is the monthly initial rate, and n is the total number of months. After 120 payments, the remaining balance is recalculated and a new payment is found for the adjustable years. To solve for payment, principal, rate, or term with a chosen compounding frequency on a fixed-rate amortizing loan, use the advanced loan calculator.

First adjusted rate

Adjusted rate=max⁡(R0−Ci, min⁡(R0+Ci, Index+Margin))\text{Adjusted rate} = \max(R_0 - C_i,\ \min(R_0 + C_i,\ \text{Index} + \text{Margin}))

R₀ is the initial annual rate, Cᵢ is the initial adjustment cap, and the index plus margin is the fully indexed rate before caps are applied. The worst-case rate in this tool is the initial rate plus the lifetime cap.

Frequently asked questions

What does 10/1 mean?
The rate is fixed for 10 years, then adjusts every 1 year for the rest of the loan term. A 30-year 10/1 ARM has 10 fixed years and 20 adjustable years.
How is the expected payment different from the worst case?
The expected payment uses the index plus margin, limited by the initial and lifetime caps. The worst-case payment assumes the rate rises by the full lifetime cap above your start rate, which may be higher than the first adjustment.
Does this include taxes or insurance?
No. Results cover principal and interest only. Property tax, insurance, and other escrow items are not included.
Can I compare this to a fixed-rate loan?
Yes. Run your loan amount and full term through the EMI calculator with a fixed rate to see the steady payment without any future adjustment.
Are the results stored?
No. Changing the fields only updates the page URL so you can copy and share your inputs.
Which currency is used?
Amounts are formatted in US dollars (USD).

Resources and references

The formulas and methods in this calculator were checked against these independent sources.