For U.S. borrowers weighing an adjustable-rate mortgage
Adjustable-rate mortgage (ARM) calculator
An adjustable-rate mortgage starts at one rate and then resets on a schedule set in the note. Enter your terms and see the payment at each adjustment: with the index unchanged, along a path you choose, and at the highest level your caps allow.
Calculate for free- No account
- No credit inquiry
- No sales follow-up
Cindrus is a calculation tool, not a financial advisor. We give no personal advice and sell no financial products.
Payment in the initial rate period: -
The result is a calculation on your figures. It is not a guaranteed saving or an offer.
Your index value plus the margin, without rounding. Your note may round it, for example to the nearest eighth of a percentage point, so check the rounding rule in your note.
This is the ceiling your caps set, not a forecast. The rate only gets there if the index rises far enough.
With the ARM at the caps, its head start is not used up within the term you entered.
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.
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.
The table shows the index path you chose, the rate after caps and floor, and the new payment, recalculated over the remaining term.
| Adjustment | Starts in month | Rate | Monthly payment | Balance at start |
|---|
- 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.
Your next step.
Take the result with you.
Free. No account.
- Write down the figures you used: you find them under «Understand the number».
- Ask what it costs in total, not only what the payment will be.
- Ask whether the rate is fixed and what can change it.
- Ask for the offer in writing, so you can compare it calmly.
- Ask what is not included in the figure.
Ready to talk to the bank?
Your figures and the right questions, on one page.
- Costs and rate
- Fees and remaining balance
- The assumptions behind the figure
Follow your loan.
Your loan and your calculations, in one place.
- Your calculations saved in one place
- Your financial overview
The account is free.
The calculator is free without an account. Not personal advice.
Your bank conversation
Ask the bank about these six things.
Based on your calculation. Not personal advice.
Your loan terms, your index assumption, every reset
Copy the terms from the paperwork
Initial rate, how long it lasts, how often the rate resets, the margin and the three caps. They are on the Loan Estimate and in the loan documents.
Choose an index path
Nobody knows where an index will be. Type the level you want to assume at the first reset and how much it moves at each one after.
Read the range
Next to your path, the calculator shows the highest rate and payment the caps permit, whatever the index does.
Index plus margin, inside the caps
When the initial rate expires, the index and the margin are added together to give the new rate, subject to the rate caps. The index moves with general market conditions. The margin is set in your loan agreement and doesn't change after closing.
Initial adjustment cap
How far the rate can move, up or down, the first time it adjusts.
Subsequent adjustment cap
How far it can move at each adjustment after that.
Lifetime cap
How far it can move in total from the initial rate, over the life of the loan. Some loans also have a floor below which the rate never falls.
Notices before your rate changes
Regulation Z requires a separate written notice ahead of the first adjustment, between 210 days and 240 days before the first payment at the new level is due. Later adjustments that change the payment come with a notice between 60 days and 120 days ahead.
Read the guide to adjustment notices →What decides an adjustable-rate payment after the first reset?
Four terms do most of the work: the index the loan follows, the margin added to it, the caps that limit each move, and how often the rate resets. The initial rate only matters until the first adjustment.
For most loans the payment is recalculated whenever the rate adjusts. If a loan recalculates the payment less often, a higher rate can leave the payment unchanged while the balance grows. This calculator assumes a new payment at every reset.
Can the rate go down too?
It can, if the index falls, but not below a floor if the loan has one. Some loan contracts only let the rate rise. Enter a negative change per adjustment to test a falling index.
Other names for the same question
ARM calculator · adjustable-rate mortgage calculator · ARM payment calculator · variable-rate mortgage calculator. Each asks how the payment on an adjustable loan can change.
Every reset spelled out, with the worst case beside it
Nothing assumed for you
No rate, margin, cap or index value is filled in.
No lender involved
The site has no lending partner and passes on nothing you enter.
Rules you can check
The notice periods and the mechanics link to the regulation and the consumer bureau pages behind them.
Our rules for ourselves
- We don't sell what you tell us.
- Every assumption is printed beside its result.
- We only show figures we can account for.
- There is no countdown and no pressure.
- Your data can be downloaded or deleted at any time.
ARM questions
What happens when my ARM resets?
On the change date the servicer takes the index value your note points to, adds the margin, applies the caps and the floor, and recalculates the payment over the time left. The calculator does the same with the figures you enter.
What do the three caps mean?
They are often written as three numbers separated by slashes: the most the rate can move at the first adjustment, at each later adjustment, and over the life of the loan above the initial rate. Enter them one by one in the cap fields.
Can the rate go down at a reset?
If the index is lower on the change date, the rate can go down, within the cap and not below the floor. Nobody knows in advance which way the index will move, so the calculator lets you choose the path.
How much notice do I get before a reset?
Before the first rate adjustment, the servicer must send a notice 210 to 240 days before the first payment at the new rate is due. When a later adjustment changes the payment, the notice comes 60 to 120 days ahead.
How does an ARM compare with a fixed-rate mortgage?
With an ARM, the calculator can set the payments against a fixed-rate loan at a rate you enter. It shows how much lower the ARM's payments are during the initial rate period and the month in which that head start would be used up if the rate climbs to the caps. How the index moves and how long you keep the loan decide the real outcome.
Where do I find my index, margin and caps?
In your note, in the adjustable-rate disclosure you received, and in the Adjustable Interest Rate (AIR) Table on page two of the Loan Estimate.
The ARM calculator is free to use.
A free Cindrus account brings your mortgage, other debts and assets into a single overview. The pricing page lists the plans and where each feature works.
Compare plans →Follow the loan past the first reset.
Modeling is free. To keep the loan alongside the rest of your finances, a free account takes a minute and no card.