ARM Mortgage Calculator
Calculate adjustable rate mortgage payments — initial fixed period + adjustment scenarios. Last Updated: May 2026
*Comparison assumes current rate +0.75% for a 30-yr fixed. Actual rates vary by lender.
📊 Payment Scenarios Over Time
💡 Is an ARM Right for You?
Understanding Your ARM Payment Results
An adjustable rate mortgage (ARM) has two distinct phases. During the fixed period (e.g., 5 years for a 5/1 ARM), your interest rate and payment stay constant — often lower than a comparable 30-year fixed rate. After that, the rate adjusts annually based on a benchmark index (typically SOFR) plus a lender margin.
The calculator above shows your initial payment during the fixed period, plus a worst-case maximum payment if rates rise by the full lifetime cap. Use the scenario table to see exactly how your payment could change each year.
ARMs are most beneficial when you plan to sell or refinance before the fixed period ends, or when you expect interest rates to fall. They carry risk if you stay longer than planned and rates rise sharply.
What Affects Your ARM Payment?
The rate during your fixed period. ARM initial rates are typically 0.5–1.5% lower than 30-year fixed rates — this is the main financial appeal of an ARM.
A 5/1 ARM is fixed for 5 years then adjusts yearly. A 7/1 ARM is fixed for 7 years. Longer fixed periods mean more payment stability but less initial savings vs. fixed rates.
Caps limit how much your rate can rise. A 2/2/5 cap means: max 2% at first adjustment, 2% each subsequent adjustment, 5% total over the loan’s life.
After the fixed period, your rate = benchmark index (SOFR) + lender margin (typically 2–3%). When SOFR rises, so does your rate and payment.
When the rate adjusts, your new payment is recalculated on the remaining balance over the remaining term. A larger balance means bigger payment swings.
ARM vs. Fixed-Rate Mortgage — Which Is Better?
| Factor | ARM | 30-Year Fixed |
|---|---|---|
| Initial Rate | ✅ Lower | ❌ Higher |
| Payment Stability | ❌ Changes after fixed period | ✅ Always same |
| Best For | Short-term owners (<7 yrs) | Long-term owners (7+ yrs) |
| Risk Level | ⚠️ Rate risk after fixed period | ✅ No rate risk |
ARM Calculator — Frequently Asked Questions
A 5/1 ARM means the interest rate is fixed for the first 5 years, then adjusts once per year after that. Other common types: 7/1 ARM (fixed 7 years), 10/1 ARM (fixed 10 years), 3/1 ARM (fixed 3 years).
ARM rate increases are limited by caps. The common 2/2/5 structure means: max +2% at first adjustment, +2% each year after, +5% total lifetime maximum. If your initial rate is 5.75%, the absolute maximum is 10.75%.
An ARM makes sense if you plan to sell or refinance before the fixed period ends, or if you expect rates to fall. For long-term homeowners (10+ years), a fixed-rate mortgage typically provides better certainty and often lower total cost.
Most modern US ARMs use SOFR (Secured Overnight Financing Rate), which replaced LIBOR in 2023. Your adjustable rate = SOFR + lender margin (typically 2.5–3.5%). The margin is set at closing and never changes.
Yes — you can refinance into a fixed-rate mortgage at any time, subject to lender qualification and closing costs. Many borrowers refinance before the fixed period ends. The break-even point on refinancing typically takes 2–3 years of monthly savings.
The worst-case payment assumes your rate rises by the full lifetime cap immediately after the fixed period. This is the highest payment you could theoretically ever face. In practice, rates adjust gradually limited by the per-adjustment cap.