5/1 ARM Calculator
See the initial payment on a 5/1 adjustable-rate mortgage — fixed for 5 years, then adjusting annually — and the payment shock once it resets.
How the 5/1 arm calculator works
A 5/1 ARM fixes your rate for five years, then adjusts once a year for the rest of the term. This tool amortizes the loan at the discounted start rate through those five years, then recalculates the payment at your estimated reset rate over the months that remain.
Five years is the middle ground among common ARMs: longer certainty than a 3/1, but a quicker reset than a 7/1 or 10/1. Each adjustment sets the rate to the index, usually SOFR, plus your fixed margin, kept inside the initial, periodic, and lifetime caps. The tool reports the first payment, the payment after reset, and the balance still owed when year five ends.
Worked example: with loan amount of $425,000, loan term (years) of 30 and initial fixed rate (5 yrs) of 5.99%, the 5/1 arm calculator shows initial monthly payment of $2,545.36.
- Payment (first 5 yrs)
- $2,545.36
- Payment after reset
- $2,922.21
- Balance at reset
- $395,432
- Rate change
- 5.99% → 7.50%
| Loan amount | Initial monthly payment |
|---|---|
| $300,000 | $1,796.72 |
| $425,000 | $2,545.36 |
| $550,000 | $3,293.99 |
| $700,000 | $4,192.35 |
The formula
The initial payment amortizes the full loan amount at the start rate over the entire term. At the first reset the adjusted rate equals index + margin, limited by the initial cap, then by periodic and lifetime caps thereafter. The remaining balance after five years re-amortizes at that capped rate over the months left.
- The rate stays fixed for exactly five years, then adjusts annually, which is the defining structure of a 5/1 ARM.
- Caps read as initial/periodic/lifetime; a 2/2/5 set limits the first move to 2 points, each later move to 2, and the total rise to 5 over the start rate.
- The estimated reset rate you enter is a planning figure; no model can predict where SOFR sits in five years.
- The margin is fixed for the life of the loan and added to whichever index value applies at each annual reset.
- Property taxes, homeowners insurance, HOA dues, and lender fees are not reflected in the payment figures shown.
Results are estimates for educational purposes and are not financial advice. Confirm exact figures with your lender or a licensed advisor.
Questions about the 5/1 arm calculator
Why is the 5/1 ARM the most common adjustable-rate mortgage?
Five years matches how long many owners actually keep a loan before they move or refinance, so the lower start rate often runs its whole course before a single reset arrives.
It balances a meaningful discount against a manageable window of certainty, which is why lenders promote it and borrowers choose it more than any other ARM.
What happens to my payment exactly at the start of year six?
The rate switches from your fixed start rate to the index plus your margin, bounded by the initial cap. The remaining balance is then re-amortized over the months left, so the payment can rise or fall depending on where the index sits.
The initial cap protects you from the full swing if the index has climbed sharply.
Should I take a 5/1 ARM if I might stay longer than five years?
It can still work, but the calculus changes. Within five years the savings are close to locked in; beyond that you absorb reset risk every year.
If you expect to stay six or seven years, compare the 5/1 against a 7/1, whose longer fixed window may be worth its slightly higher start rate for the extra certainty.
Is the 5/1 ARM Calculator free to use?
Yes. Every calculator on MortgageLoansCalculator is completely free, with no sign-up, login or paywall. Run as many scenarios as you like.
What is a 5/1 ARM?
A 5/1 ARM has a rate fixed for the first five years, then adjusts once a year afterward to an index plus a margin, within caps.
It suits buyers who expect to sell or refinance within about five years and want a lower starting rate.
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