Adjustable-Rate Mortgage Calculator

The future rate is a scenario you enter. It is not a forecast and it is not guaranteed.

Published by the Mortgage Guide editorial team. Rate assumptions and content updated October 2026. This page is educational. It is not a loan offer, approval, or personalized financial advice.

The scenario rate is a rate you want to test. It is not a forecast. Caps limit how high this model lets that test go.

Loan amount

Full term in years

Initial rate

Years before the first adjustment

Rate to test after the first adjustment

Periodic cap

Lifetime cap above the initial rate

First payment month

Initial payment $1,918.56

Balance after the initial period $297,774.07

First adjustment cannot exceed 8.000% in this model.

Lifetime maximum rate 11.000%

Tested rate actually used 8.000%

Payment at the tested rate $2,298.27

Payment at the lifetime cap $2,918.52

Neither future payment is guaranteed. The index and margin on a real ARM note control the adjustment, subject to the caps in that note.

How this calculator works

The initial payment amortizes the full term at the initial rate.
After the initial period, the model takes the remaining balance.
The tested rate cannot rise above the periodic cap or the lifetime cap.
A new payment is calculated on the remaining balance and remaining years.

Caps limit the test, they do not predict the index

A real ARM note names an index and a margin. The rate after adjustment is that sum, subject to the caps. This page does not fetch an index.

Use the scenario field to ask 'what if the rate becomes this?' The result shows the capped rate the model actually used, so a number above the cap is not silently applied.

Sources

CFPB: Owning a home

Common questions

Will my payment become the lifetime-cap payment?

Not necessarily. That line is the high end of this model if the rate reaches the lifetime cap and the loan is recast on the remaining balance. Your note controls the real adjustment.

Does the initial payment include taxes and insurance?

No. This calculator is principal and interest only.

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