ARM Calculator OnlineUnited States Part of Cindrus (opens in a new tab)

ARM payment calculator

Enter the loan's terms and your index assumption. The rate path builds as you type.

Your ARM

Empty fields by design. The results come only from what you enter.

The amount borrowed, or the balance today if the loan is already running.

The rate for the initial rate period, from your note or Loan Estimate. Use the interest rate, not the APR.

How long the initial rate applies before the first adjustment.

How often the rate can change after the first adjustment.

The latest value of your index. Your note says which date counts, often a set number of days before the change date.

Your assumption. Use a minus sign for a fall.

The amount added to the index at each adjustment. It is set in the note and does not change.

The most the rate can move at the first adjustment.

The most the rate can move at each later adjustment.

The most the rate can ever rise over the initial rate.

The rate can never go below this. Many notes set it at the margin; check yours.

The full term of the loan.

Next to the ARM, enter the rate of a fixed-rate loan you are looking at. Leave it empty to skip the comparison.

Payment in the initial rate period: -

The result is a calculation on your figures. It is not a guaranteed saving or an offer.

The rate on this loan can change after the initial rate period, and the payment can rise.

An adjustable rate can rise after the initial rate period, and so can the payment. The paths on this page are illustrations, not predictions.

Every result on this site comes from the numbers you enter and the assumptions shown.

Data used: the terms and index path you entered. The rate and costs you can actually obtain may differ.

These are the payments your terms produce along the paths shown. They are not a forecast of rates, a loan offer or a personal recommendation.

For illustrative purposes only. Not a loan offer or commitment to lend. Cindrus is not a lender, mortgage broker or loan originator, we pass no information to lenders, and no lender pays us.

Put your ARM in Cindrus

Enter your adjustable-rate mortgage in Cindrus by hand. It sits in your overview in US dollars beside your home, and your net worth follows when you change the balance.

On a paid plan, Cindrus emails you before each reset with what the rate would be from the latest published index value, your margin and your caps. It is a scenario from your own figures, with the source and date of the index value, not the rate your servicer will set.

Create a free Cindrus account (opens in a new tab) Free account. Record your adjustable-rate loan and see it beside your assets and other debt. No card needed.
What the path assumes:
  • The index follows exactly the path you typed.
  • The payment is recalculated at every adjustment so the loan still ends on schedule.
  • The balance never grows, because each payment covers the interest.
  • There are no prepayments, fees or rate-lock costs.
  • The initial rate applies from the first payment until the first adjustment.

How the adjustments are calculated

At each change date, the new rate is the index plus the margin. It is then held within the cap for that adjustment, no lower than the floor and no higher than the initial rate plus the lifetime cap.

After each adjustment, the payment is recalculated so the remaining balance is paid off over the remaining term at the new rate.

The highest path assumes the rate moves up by the full cap at every adjustment until it reaches the lifetime limit, and stays there.

The ARM comparison adds up the monthly difference between the ARM payment and the payment on a fixed-rate loan at the rate you entered, and shows when the running total turns.

Caps, margin, floor and index are set in your note and the ARM disclosure. If they differ from what you entered, your note applies.

Sources

  1. CFPB: «For an adjustable-rate mortgage (ARM), what are the index and margin, and how do they work?» (opens in a new tab)
  2. CFPB: «What are rate caps with an adjustable-rate mortgage (ARM), and how do they work?» (opens in a new tab)
  3. 12 CFR 1026.19(b) (Regulation Z) and CFPB «Consumer Handbook on Adjustable-Rate Mortgages» (opens in a new tab)
  4. 12 CFR 1026.20 (Regulation Z), «Disclosure requirements regarding post-consummation events» (opens in a new tab)

How index, margin and caps set the new rate →