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APR Calculator for Adjustable Rate Mortgages

Use this calculator to find the APR on your adjustable rate mortgage.

Inputs
$
%
$

Estimates only. Adjust any value to recalculate instantly.

Results
Initial-rate APR 5.672% versus a 5.50% initial rate
Initial rate 5.50%
APR (initial) 5.672%
Points cost $3,200
Total fees $6,000
Upfront cost
Upfront cost Points: $3.2kOther fees: $2.8k
  • Points $3.2k
  • Other fees $2.8k
Loan balance Balance (initial rate)
Loan balance: Balance (initial rate) $316k$237k$158k$79k$0 Yr 1Yr 6Yr 11Yr 16Yr 21Yr 26

For an ARM, the standard APR is based on the initial rate plus fees, so it understates the cost if the loan later adjusts upward. Treat it as a starting comparison and check the rate caps and fully-indexed rate too.

Amortization at the initial rateView table
YearPrincipalInterestBalance
1$4,311$17,492$315,689
2$4,554$17,249$311,135
3$4,811$16,992$306,325
4$5,082$16,721$301,243
5$5,369$16,434$295,874
6$5,672$16,132$290,202
7$5,992$15,812$284,211
8$6,329$15,474$277,881
9$6,687$15,117$271,195
10$7,064$14,739$264,131
11$7,462$14,341$256,669
12$7,883$13,920$248,786
13$8,328$13,475$240,458
14$8,797$13,006$231,661
15$9,294$12,509$222,367
16$9,818$11,985$212,549
17$10,372$11,431$202,177
18$10,957$10,846$191,221
19$11,575$10,228$179,646
20$12,228$9,575$167,418
21$12,918$8,886$154,500
22$13,646$8,157$140,854
23$14,416$7,387$126,438
24$15,229$6,574$111,209
25$16,088$5,715$95,121
26$16,996$4,807$78,126
27$17,954$3,849$60,171
28$18,967$2,836$41,204
29$20,037$1,766$21,167
30$21,167$636$0

How the apr calculator for adjustable rate mortgages works

It finds the APR based on the ARM’s initial rate and your upfront points and fees — the rate at which the net proceeds equal the present value of the initial payments. It standardises ARM offers for comparison.

Worked example

Worked example: with loan amount of $320,000, initial rate of 5.50% and loan term (years) of 30, the apr calculator for adjustable rate mortgages shows initial-rate apr of 5.672%.

Initial rate
5.50%
APR (initial)
5.672%
Points cost
$3,200
Total fees
$6,000

The formula

APR is the rate r where (loan − points − fees) = present value of payments at the initial rate. Points cost = loan × points %.

Results are estimates for educational purposes and are not financial advice. Confirm exact figures with your lender, plan administrator or advisor.

Frequently asked

Questions about the apr calculator for adjustable rate mortgages

How is ARM APR different from fixed-rate APR?

A fixed-rate APR is exact for the loan’s life; an ARM APR is based on the initial rate (and assumed future rates), so it can understate the cost if the loan adjusts upward.

Can I rely on the ARM APR alone?

Not entirely. Also compare the margin, the index, and the rate caps — they determine how high your payment can actually go after the fixed period.

Why include points and fees?

Because they are real upfront costs. Folding them into the APR lets you compare ARM offers with different rates and fee structures on one number.

Is the APR Calculator for Adjustable Rate Mortgages free to use?

Yes. Every calculator on FinCalculators is completely free, with no sign-up, login or paywall. You can run as many scenarios as you like.

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