Fixed vs. ARM Mortgage Calculator
See the payment advantage during an ARM’s introductory period and the cost if the rate later adjusts.
Verify this calculatorMaintained
See what the result uses—and what it cannot know.
Sumvoro calculates deterministically from the visible inputs. It does not invent lender terms, local rules, market values, medical facts, or professional judgments.
- 1 · InputsCheck every entered value against the latest statement, quote, measurement, or official source.
- 2 · Formula
Each loan uses monthly amortization. The ARM uses its introductory rate through the fixed period, then recalculates payment at the modeled adjusted rate over the remaining term. - 3 · SensitivityUse Insights to run a lower and higher case. If the conclusion changes easily, collect better information or leave more margin.
- 4 · ScopeThis tool is maintained and covered by automated calculation tests. Provider timing, rounding, and omitted facts can still change a real-world result.
- Formula release
- 2026.10-r4
- Release date
- October 10, 2026
- Review status
- Maintained
- Source review
- September 12, 2026
Optional readingLearn how this calculator works
How the fixed vs. arm mortgage calculator works
Compare a fixed-rate mortgage with an adjustable-rate mortgage across a chosen ownership horizon and modeled future ARM rate.
Each loan uses monthly amortization. The ARM uses its introductory rate through the fixed period, then recalculates payment at the modeled adjusted rate over the remaining term.
Read our calculation methodology and limitations.
Example
Compare a 30-year fixed mortgage at 6.5% with a 5-year ARM at 5.75% that is modeled to adjust to 7.25% for the rest of a seven-year horizon.
What affects the result
- The future ARM rate is an assumption, not a forecast.
- Real ARMs can adjust more than once and have periodic and lifetime caps.
- Compare lender disclosures, margins, indexes, fees, and adjustment dates.
Frequently asked questions
Does this predict future rates?
No. You choose a modeled post-introductory rate to test a scenario.
Does a lower initial payment mean the ARM is cheaper?
Not necessarily. Compare total payments and remaining balance across the period you expect to keep the loan.