Fixed Rate vs. ARM — Which Mortgage Saves You More?
Compare a Fixed-Rate and Adjustable-Rate mortgage side by side — see payment differences, total interest costs, the break-even point, and a year-by-year balance chart.
| Metric | 🔒 Fixed | 📈 ARM |
|---|---|---|
| Click "Compare loans" to see results | ||
| Year | Fixed Payment | Fixed Balance | ARM Payment | ARM Rate | ARM Balance |
|---|---|---|---|---|---|
| Calculate to see schedule | |||||
How to Use the ARM vs. Fixed Comparison Calculator
In under two minutes, get a complete financial picture of both loan types — including which one wins over your specific planning horizon and the exact month the cheaper loan switches.
Enter Home Price, Down Payment & Loan Term
Input your home price and down payment — use the slider to quickly explore different scenarios. Select a loan term (15, 20, or 30 years). The loan amount and LTV are calculated instantly. These inputs apply equally to both loan types, so you’re comparing apples to apples.
Set Your Planning Horizon
Enter the number of years you expect to own the home before selling or refinancing. This is the most important variable — the calculator compares cumulative costs over exactly this period and flags which loan wins. A 5-year horizon favours ARMs; a 20-year horizon almost always favours fixed.
Enter Both Loan Rates & ARM Details
Enter your fixed APR, then set the ARM type (3/1, 5/1, 7/1, or 10/1), initial rate, expected rate after adjustment, and the lifetime rate cap. For a realistic worst-case, add the lifetime cap to the initial rate and enter that as the adjusted rate. The rate slider lets you adjust the fixed rate visually.
Review Results & Download the PDF Report
The results panel shows both monthly payments, the winner banner for your horizon, the break-even month, a detailed comparison table, summary savings cards, and a balance-over-time chart. Download the 2-page PDF for a shareable, printer-ready report you can take to your lender or advisor.
Fixed Rate vs. ARM — At a Glance
Both loans use the same principal and term. The difference is entirely in how the interest rate behaves over time — and that difference can mean tens of thousands of dollars in total cost.
Predictable payments for life
Your interest rate is locked at origination and never changes, regardless of market conditions. Your principal and interest payment is the same in month 1 as it is in month 360.
- Monthly payment never increases
- Full rate certainty — no index exposure
- Ideal for long-term homeowners (10+ years)
- Lower total interest when held to maturity
- Easier budgeting and financial planning
Lower start rate, future variability
The rate is locked for an initial fixed period (3, 5, 7, or 10 years), then adjusts annually based on a market index plus your lender’s margin — subject to rate caps.
- Lower initial rate than a comparable fixed loan
- Saves money if you sell or refi before adjustment
- Ideal for short-to-medium hold periods (3–7 yrs)
- Rate caps limit worst-case payment increases
- Could benefit from falling market rates at reset
What This Calculator Shows You
Most comparison tools show you two monthly payments. This one goes further — it calculates total cost over your actual horizon, pinpoints the exact break-even month, and charts how balances diverge year by year.
Side-by-Side Monthly Payments
Initial monthly P&I for both loans displayed in a large hero comparison — Fixed in blue, ARM in orange. The ARM also shows the post-adjustment payment so you can see both phases of the adjustable loan.
Break-Even Month
The exact month when the ARM’s cumulative payments overtake the fixed loan’s cumulative payments. Before this point, the ARM has cost less. After it, the fixed loan has been cheaper overall. This single number often settles the decision.
Winner Banner & Horizon Savings
A clearly labelled banner names which loan wins over your planning horizon and shows exactly how much you save by choosing it. If the difference is under $500, the calculator calls it a tie and recommends choosing based on risk tolerance instead.
9-Row Comparison Table
A detailed side-by-side table covering loan amount, term, initial rate, adjusted rate, both monthly payments, total interest over the full term, total paid over your horizon, and remaining balance at year N — with checkmarks on the better value in each row.
Balance Over Time Chart
A line chart overlaying both loan balances year by year across the full term. The divergence between the two lines visually shows how the ARM’s lower initial rate affects paydown speed — and where the adjusted rate changes the curve.
Year-by-Year Schedule & PDF Report
A full amortisation table for both loans in a single accordion — tracking payment, rate, and balance year by year with your horizon row highlighted. The 2-page PDF export packages every figure into a clean, shareable report.
The Fixed vs. ARM Decision in Numbers
Three Borrowers — Three Different Answers
The right loan depends almost entirely on your timeline and risk tolerance. These three profiles illustrate exactly where each loan type wins — and why the same numbers can produce opposite conclusions.
You’re buying a home you expect to sell in 4–6 years — a starter home, a relocation property, or a stepping-stone before your forever home. A 7/1 ARM lets you lock in a lower rate for 7 years and sell before the rate ever adjusts. The initial savings versus a 30-year fixed can reach $15,000–$20,000 over the hold period, with zero rate-adjustment risk because you sell first. This calculator will confirm the ARM wins well before the break-even month.
- Choose a fixed period that exceeds your planned hold — a 7/1 for a 5-year plan is safer than a 5/1
- Use the horizon feature to quantify exact dollar savings versus the fixed rate
- Keep a refinance option open if your timeline extends unexpectedly
You’re buying a forever home — or at least one you plan to live in for 15+ years. Once you stay past the break-even month, the fixed loan’s cumulative cost pulls ahead. With a long horizon, the total interest on a fixed loan is typically lower than an ARM where the adjusted rate has been applied for a decade or more. Rate certainty also means no budget risk if market rates spike at renewal.
- Run the comparison with your adjusted rate set to the worst case (initial + lifetime cap)
- Check the break-even month — if it’s before year 7, the fixed advantage is significant
- Factor in the value of payment stability for long-range financial planning
You believe rates will fall before your ARM adjusts — and you plan to either refinance into a fixed rate or benefit from a lower adjusted payment. This is a legitimate strategy, but it requires a clear plan and financial flexibility. Use this calculator to model two scenarios: one where the adjusted rate equals today’s fixed rate (optimistic), and one where the lifetime cap applies (worst case). The gap between those two outcomes tells you how much risk you’re carrying.
- Model both the best-case and worst-case adjusted rate — decide if the spread is acceptable
- Check your equity at the adjustment date using the balance figure to confirm refinanceability
- Include estimated refinancing costs ($3,000–$6,000) in your total cost comparison
7 Things to Know Before Choosing Between ARM and Fixed
The monthly payment difference is only part of the story. These seven principles will help you make a comparison that accounts for real-world risk, total cost, and your personal financial situation.
Compare Total Cost Over Your Horizon — Not Just Monthly Payment
The ARM’s lower initial payment looks attractive. But if you stay past the break-even month, the fixed loan may have cost you less in total. Use the “total paid over N years” figure in the summary cards — not the headline monthly number — as the basis for your decision.
Always Enter a Worst-Case Adjusted Rate — Not Just Your Expected Rate
Add the ARM’s lifetime cap to the initial rate and enter that as the adjusted rate. This models the maximum payment the ARM can ever produce. If the fixed loan still wins on total cost at the worst-case adjusted rate, you know the fixed is genuinely safer. If the ARM still wins even at the cap, you have a clear answer.
The Break-Even Month Is the Decision Hinge — Find It Before Anything Else
If your planned horizon is comfortably before the break-even month, choose the ARM. If your horizon is well after it, choose the fixed. Only if your horizon is close to the break-even — within 12–18 months — should you weigh secondary factors like rate risk and income stability.
The ARM’s Adjusted Rate Applies to ~91% of the Original Balance
On a 30-year loan, you’ve paid off less than 10% of the principal after 5 years. The adjusted rate applies to a large remaining balance — which is why a 2% rate jump can add $250–$400/month to your payment. Use the “Balance at year N” row in the comparison table to see exactly what balance the new rate will be calculated on.
Ask Your Lender for the ARM’s Exact Cap Structure Before Comparing
Every ARM has three caps: initial adjustment cap (at first reset, commonly 2% or 5%), periodic cap (per subsequent reset, typically 2%), and lifetime cap (total, typically 5%–6%). These numbers must come from your official Loan Estimate. Don’t model a comparison without them — they define the worst-case adjusted rate, which is the critical stress-test input.
A Lower ARM Payment Is Not a Reason to Buy More Home
A common mistake is using the ARM’s lower initial payment to qualify for — or stretch into — a more expensive home than the 30-year fixed would allow. If the adjusted payment on that more expensive home becomes unmanageable, you’ve built a financial trap. Use the ARM’s savings to reduce financial stress or build equity faster, not to justify a larger purchase price.
Download the PDF and Bring It to Both Loan Conversations
The 2-page PDF report gives you a structured, lender-ready summary of both loan types with your exact numbers — payments, balances, total interest, and the break-even month clearly stated. Presenting this to a lender demonstrates you understand the full cost picture, not just the initial monthly payment, which typically leads to a more transparent conversation.
Frequently Asked Questions
Everything you need to know about how this calculator compares the two loan types, what the break-even means, and how to interpret the results for your specific situation.
Disclaimer: All results produced by the ARM vs. Fixed Mortgage Comparison Calculator are estimates for educational and planning purposes only. ARM projections model a single rate adjustment to the fully-indexed rate you enter at the end of the initial fixed period; they do not model subsequent annual adjustments, periodic caps, teaser-rate structures, interest-only periods, or payment caps. The Fixed-rate projection assumes a constant rate for the full loan term. Actual loan performance will depend on market index values, lender margins, rate caps, and the specific terms of your loan at origination. Results may differ materially from real loan outcomes. Always review your official Loan Estimate and consult a licensed mortgage professional before making any financing decision.