Mortgage Calculators

Interest Only ARM Calculator

An interest-only ARM keeps payments very low at first by deferring all principal. See that payment and the jump when amortization begins.

Inputs

Loan amount

Interest-only rate

Interest-only period (years)

Total term (years)

Rate after IO period

Estimates only. Change any value to recalculate instantly.

Interest-only payment $1,916.67 jumps to $3,101.20 after 10 years

Interest-only payment $1,916.67

Payment after IO period $3,101.20 +$1,184.53/mo

Balance still owed $400,000 unchanged during IO

Rate after reset 7.00%

The payment jump

Interest-only $1.9k
Added principal $1.2k

Loan balance Balance

Two risks stack here: the interest-only period builds no equity, and the ARM can reset to a higher rate. When both hit at once, the payment can jump sharply — plan for it.

Payment & balance by yearView table

Year	Monthly payment	Balance
1	$1,916.67	$400,000
2	$1,916.67	$400,000
3	$1,916.67	$400,000
4	$1,916.67	$400,000
5	$1,916.67	$400,000
6	$1,916.67	$400,000
7	$1,916.67	$400,000
8	$1,916.67	$400,000
9	$1,916.67	$400,000
10	$1,916.67	$400,000
11	$3,101.20	$390,484
12	$3,101.20	$380,281
13	$3,101.20	$369,339
14	$3,101.20	$357,607
15	$3,101.20	$345,027
16	$3,101.20	$331,537
17	$3,101.20	$317,072
18	$3,101.20	$301,561
19	$3,101.20	$284,929
20	$3,101.20	$267,095
21	$3,101.20	$247,971
22	$3,101.20	$227,465
23	$3,101.20	$205,477
24	$3,101.20	$181,899
25	$3,101.20	$156,617
26	$3,101.20	$129,507
27	$3,101.20	$100,437
28	$3,101.20	$69,266
29	$3,101.20	$35,841
30	$3,101.20	$0

How this calculator works

This calculator runs entirely in your browser — nothing you enter is sent anywhere, and there is no sign-up. Change any input and the result, breakdown, and schedule update instantly.

Rate and cost fields are pre-filled with current benchmarks (Federal Reserve / Freddie Mac via FRED (St. Louis Fed)), so your first result is already realistic — replace them with your own quote to see your numbers. To weigh one option against another, use the loan comparison calculator.

30-year fixed mortgage rate, 2019–2026

Source: Freddie Mac PMMS via FRED. Annual averages; latest weekly reading shown.

Common questions

Is this calculator free, and do I need to sign up?

Yes and no — it is completely free and asks for no account or personal details. Every calculation happens in your browser, so nothing you type is stored or sent to us.

How accurate are the results?

The math is exact for the inputs you give it, but the defaults are national benchmarks — your real rate, fees, taxes, and insurance will differ. Treat the result as a close estimate to refine with a real quote.