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ARM (Adjustable-Rate Mortgage) Calculator

Model a 5/6, 7/6, or 10/6 SOFR ARM. See the intro payment, what payments could look like at the first adjustment, and the worst case once the lifetime cap is hit.

Your numbers

Loan

$
yrs
yrs

Common ARMs: 5, 7, or 10 years

mo

Today's SOFR ARMs adjust every 6 months

%

Illustrative example rate. Not an available or quoted rate.

Index & margin

%

SOFR is the benchmark used by most new ARMs

%

Added to the index at each adjustment

Caps

%

First adjustment limit vs intro

%

Each later adjustment

%

Max ever over intro rate

A common cap structure written as 2/1/5 means 2% initial, 1% periodic, 5% lifetime.

Scenario

Intro payment

Monthly principal & interest (intro period)$2,552

Fixed for the first 7 years at 6.125%.

At the first adjustment

Best case (index stays at today)$2,766
Worst case (initial cap hit)$3,795

Best case uses today's index + margin. Worst case bumps the rate by the full initial cap.

Lifetime worst case

If the lifetime cap is hit$3,795

Rate of 11.125% is the highest you could ever pay on this ARM.

Total interest (under chosen scenario)

Interest under this index path$841,871
Interest if rate stayed at intro$498,707
Extra interest vs staying at intro$343,164
Results are estimates based on user inputs and do not represent loan terms, APR, or a financing offer. Pre-filled values are illustrative examples, not available or quoted rates. Actual terms depend on credit, property, program, and underwriting.

Projected rate and payment

Shaded area shows the intro fixed period. After that, the rate adjusts every 6 months under your chosen scenario.

first adjustmentYr 1Yr 16Yr 3011.13%6.13%$3,795$2,552
Rate (%)Monthly payment ($)

Year-by-year projection

YearRate (start)Monthly P&IInterest paidPrincipal paidEnd balance
16.125%$2,552$25,585$5,038$414,962
26.125%$2,552$25,268$5,356$409,606
36.125%$2,552$24,930$5,693$403,912
46.125%$2,552$24,572$6,052$397,860
56.125%$2,552$24,190$6,433$391,427
66.125%$2,552$23,785$6,839$384,589
76.125%$2,552$23,354$7,269$377,319
811.125%$3,795$41,789$3,755$373,565
911.125%$3,795$41,349$4,194$369,371
1011.125%$3,795$40,858$4,685$364,685
1111.125%$3,795$40,310$5,234$359,451
1211.125%$3,795$39,697$5,847$353,604
1311.125%$3,795$39,012$6,532$347,072
1411.125%$3,795$38,247$7,297$339,776
1511.125%$3,795$37,393$8,151$331,625
1611.125%$3,795$36,438$9,105$322,520
1711.125%$3,795$35,372$10,172$312,348
1811.125%$3,795$34,181$11,363$300,985
1911.125%$3,795$32,850$12,693$288,292
2011.125%$3,795$31,364$14,180$274,112
2111.125%$3,795$29,703$15,840$258,271
2211.125%$3,795$27,848$17,695$240,576
2311.125%$3,795$25,776$19,767$220,809
2411.125%$3,795$23,462$22,082$198,726
2511.125%$3,795$20,876$24,668$174,058
2611.125%$3,795$17,987$27,557$146,502
2711.125%$3,795$14,760$30,784$115,718
2811.125%$3,795$11,155$34,389$81,329
2911.125%$3,795$7,128$38,415$42,914
3011.125%$3,795$2,630$42,914$0

Thinking about an ARM?

An ARM can make sense when you expect to move or refinance before the intro period ends. Talk it through with a loan officer to see if the math works for your plans.

Discuss Your Scenario

Want a plain-English walkthrough? ARM vs fixed-rate decision guide.

Frequently asked questions

How does a SOFR ARM actually work?
You get a fixed intro rate for the first 5, 7, or 10 years. After that, every 6 months the rate adjusts to the current SOFR index plus a fixed margin, bounded by rate caps. Today's new ARMs are almost all SOFR-based.
What do the caps mean on an ARM?
Caps are written as three numbers, for example 2/1/5. The first number is how much the rate can move at the first adjustment, the second is how much it can move at each later adjustment, and the third is the maximum the rate can ever be above the intro rate.
When does an ARM make sense?
Usually when you expect to sell or refinance before the intro period ends, or when the ARM rate is meaningfully lower than the 30-year fixed rate. If you plan to stay in the home long past the intro period and rates are flat to rising, the fixed tends to win.
Is this calculator a quote?
No. It is an educational tool. Your real intro rate, margin, and caps will come from the loan program and lock you choose on your actual loan application.

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Related reading

Want the story behind the numbers?

  • ArticleWhat actually moves mortgage rates (and what does not)What drives the index your ARM resets against.Read
  • HubWhen to refinancePlan the refi you might do before your first reset.Read
  • HubConventional loan basicsHow ARM and fixed conventional pricing compare.Read

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