Choosing between a fixed-rate and variable-rate mortgage is a critical decision that affects your monthly payment and total cost for years to come. Here’s how to decide.
Fixed vs Variable Rate: Side-by-Side
| Feature | Fixed-Rate Mortgage | Adjustable-Rate Mortgage (ARM) |
|---|---|---|
| Interest rate | Stays the same for entire term | Fixed for intro period, then adjusts |
| 2026 typical rate | 6.50% (30-year) | 5.75% (5/1 ARM intro) |
| Monthly payment | Never changes | Changes after fixed period |
| Predictability | 100% predictable | Uncertain after intro period |
| Best when rates are | Low (lock in forever) | High (benefit when rates drop) |
| Popular terms | 15-year, 30-year | 5/1, 7/1, 10/1 ARM |
| Risk level | Low | Medium to high |
| Share of mortgages (2026) | 88% | 12% |
How ARM Rates Adjust
After the initial fixed period, ARMs adjust based on a benchmark index plus a margin:
| ARM Component | Example |
|---|---|
| Index (e.g., SOFR) | 4.25% |
| Margin (fixed by lender) | +2.75% |
| New rate | 7.00% |
| Annual adjustment cap | ±2% per year |
| Lifetime cap | Initial rate + 5-6% |
| Floor | Usually the margin (2.75%) |
Common ARM Types
| ARM Type | Fixed Period | When It Adjusts | Best For |
|---|---|---|---|
| 5/1 ARM | 5 years | Annually after year 5 | Moving within 5-7 years |
| 7/1 ARM | 7 years | Annually after year 7 | Moving within 7-10 years |
| 10/1 ARM | 10 years | Annually after year 10 | Want lower rate, longer stability |
| 5/6 ARM | 5 years | Every 6 months after year 5 | Avoid if possible (frequent changes) |
Payment Comparison: $400,000 Mortgage
Fixed Rate at 6.50%
| Year | Monthly Payment | Annual Payment | Remaining Balance |
|---|---|---|---|
| 1-30 | $2,528 (always) | $30,336 | Decreasing predictably |
| Total interest | $510,000 |
5/1 ARM at 5.75% (Best Case: Rates Drop)
| Year | Rate | Monthly Payment | Annual Payment |
|---|---|---|---|
| 1-5 | 5.75% | $2,334 | $28,008 |
| 6-10 | 5.25% | $2,254 | $27,048 |
| 11-30 | 4.75% | $2,086 | $25,032 |
| Total interest | $395,000 |
5/1 ARM at 5.75% (Worst Case: Rates Rise)
| Year | Rate | Monthly Payment | Annual Payment |
|---|---|---|---|
| 1-5 | 5.75% | $2,334 | $28,008 |
| 6 | 7.75% | $2,905 | $34,860 |
| 7 | 9.75% | $3,430 | $41,160 |
| 8-30 | 11.75% (cap) | $3,915 | $46,980 |
| Total interest | $685,000 |
In the worst case, the ARM costs $175,000 MORE than the fixed-rate mortgage.
When Fixed Rate Is Better
| Scenario | Why Fixed Wins |
|---|---|
| Planning to stay 10+ years | Rate certainty for the long term |
| Rates are historically low | Lock in before they rise |
| On a tight budget | Can’t absorb payment increases |
| Prefer no financial stress | Peace of mind has value |
| Refinancing unlikely | Fixed is set-it-and-forget-it |
When ARM Is Better
| Scenario | Why ARM Wins |
|---|---|
| Moving or selling within 5-7 years | Save with lower intro rate |
| Rates are likely to fall | ARM benefits from decreasing rates |
| High income, low risk tolerance isn’t an issue | Can absorb potential increases |
| Plan to refinance | Will switch before adjustment period |
| Very large loan (jumbo) | ARM savings are more significant |
| Rates are historically high | More room for rates to decline |
Current Rate Comparison (2026)
| Product | Average Rate | Monthly Payment ($400,000) | 5-Year Cost |
|---|---|---|---|
| 30-year fixed | 6.50% | $2,528 | $151,680 |
| 15-year fixed | 5.80% | $3,338 | $200,280 |
| 5/1 ARM | 5.75% | $2,334 | $140,040 |
| 7/1 ARM | 6.00% | $2,398 | $143,880 |
| 10/1 ARM | 6.25% | $2,463 | $147,780 |
The 5/1 ARM saves about $11,640 over the first 5 years compared to the 30-year fixed — but with uncertainty afterwards.
ARM Caps and How They Protect You
| Cap Type | Typical Limit | What It Does |
|---|---|---|
| Initial adjustment cap | 2% | Limits first rate change after fixed period |
| Annual adjustment cap | 2% | Limits each subsequent annual change |
| Lifetime cap | 5-6% | Maximum total increase over initial rate |
| Payment cap | 7.5% | Limits how much payment can increase (some ARMs) |
With a 5.75% initial rate and 5% lifetime cap, your rate could never exceed 10.75% — still potentially expensive on a large loan.
Historical Perspective
| Period | 30-Year Fixed | ARM Rate | Winner |
|---|---|---|---|
| 2019-2021 (falling rates) | 3.0-3.5% | 2.5-3.0% | Fixed (locked in historic lows) |
| 2022-2023 (rising rates) | 6.5-7.5% | 5.5-6.5% | ARM initially, but painful adjustments later |
| 2024-2026 (stabilizing) | 6.3-6.7% | 5.5-6.0% | Depends on future direction |
For historical context, see our mortgage rate history guide.
Bottom Line
For most homebuyers who plan to stay long-term, a fixed-rate mortgage provides certainty and protection against rate increases. ARMs can make sense for shorter-term ownership or when rates are unusually high and likely to fall. If you choose an ARM, make sure you can afford the worst-case payment — and have a plan to refinance or sell before the adjustment period becomes problematic.
Compare rates with our mortgage payment calculator and see what you can afford with our mortgage affordability calculator.