ARM vs Fixed Rate Mortgage Calculator
See the introductory savings and the ceiling the loan can reach, side by side.
What This Calculator Does
Runs an adjustable rate mortgage next to a fixed rate loan over the same term: the payment during the intro period, the payment after the first adjustment, and the worst-case payment the initial, periodic, and lifetime caps permit — so you are comparing the ceiling rather than the teaser.
Who Is This For
Buyers offered an ARM at a lower intro rate than their fixed quote, owners who plan to sell or refinance before the first adjustment, and anyone in Miami who wants to know what happens if they are still holding the loan when it adjusts.
How It Works
Enter the loan amount, the ARM's intro rate and fixed-period length, its caps, and the fixed rate you were quoted. The calculator returns both payment paths and the highest payment the ARM can ever reach.
Frequently Asked Questions
What do ARM caps actually limit?
Three separate ceilings. The initial cap limits how far the rate can move at the first adjustment, the periodic cap limits each adjustment after that, and the lifetime cap sets the highest rate the loan can ever reach. Together they define your worst case, and your lender has to disclose all three before you sign.
Should I qualify myself on the intro rate?
No. Qualify on the worst-case payment. The intro rate is temporary by design, and if your budget only works while it lasts, you are relying on selling, refinancing, or a rate move that none of you control.
When does an ARM make sense?
When your horizon is genuinely shorter than the fixed period — a known relocation, a property you intend to sell, or a bridge to a different financial position. If you plan to hold the home indefinitely, the fixed loan removes the one variable you cannot manage.
How does an ARM compare with today's fixed rates?
Benchmark 30-year fixed rates have run near 6.6-6.7% in mid-2026, and ARMs are typically priced below that during the intro period. The calculator shows what that discount is worth over the years you actually keep the loan rather than over the full term.
What if I cannot refinance later?
That is exactly the risk the caps exist to bound. Refinancing depends on rates, your credit, and the property's appraised value at some future moment, none of which are promised to you. Run the worst-case column as though refinancing were unavailable, and decide from there.