The Rate-to-Payment Relationship
A 1% increase in mortgage rates doesn’t increase your payment by 1%. It increases it by roughly 10-12%. This nonlinear relationship is why rate movements have such an outsized impact on affordability.
On a $320,000 loan (30-year fixed):
| Rate | Monthly P&I | vs. 5% |
|---|---|---|
| 5.0% | $1,718 | — |
| 5.5% | $1,817 | +$99/mo |
| 6.0% | $1,919 | +$201/mo |
| 6.5% | $2,023 | +$305/mo |
| 7.0% | $2,129 | +$411/mo |
| 7.5% | $2,238 | +$520/mo |
That 2.5% rate swing from 5% to 7.5% adds $520/month — $6,240/year — to the same loan amount. Over 30 years, you’d pay an additional $187,000 in interest.
Buying Power Math
At a fixed payment budget of $2,000/month (principal and interest), here’s how much home you can afford:
| Rate | Max Loan | With 20% Down |
|---|---|---|
| 5.0% | $372,600 | $465,800 |
| 5.5% | $352,300 | $440,400 |
| 6.0% | $333,500 | $416,900 |
| 6.5% | $316,000 | $395,000 |
| 7.0% | $300,000 | $375,000 |
| 7.5% | $285,300 | $356,600 |
From 5% to 7.5%, you lose $109,200 in purchasing power on the same monthly budget. That’s a 23% reduction in the home you can buy.
Rate Buydowns: When They Make Sense
Paying discount points (each point = 1% of loan amount) to reduce your rate can make sense if you plan to hold the loan long enough to recoup the cost.
One point on a $320,000 loan costs $3,200 and typically reduces the rate by 0.25%. That saves about $50/month. Break-even: 64 months (5.3 years).
If you’ll keep the loan 7+ years, buying points is mathematically favorable. Under 5 years, skip it.
Temporary Buydowns
Builder-offered 2-1 or 3-2-1 buydowns reduce your rate temporarily (2% below market in year 1, 1% below in year 2, then full rate). These are marketing tools, not savings vehicles. You’re paying full price for the home — the builder is just prepaying some interest from their margin.
They make sense only if you genuinely plan to refinance before the full rate kicks in, and you have strong reason to believe rates will be lower by then.
ARMs: Calculated Risk or Ticking Bomb?
Adjustable-rate mortgages (5/1, 7/1, 10/1 ARMs) offer lower initial rates — typically 0.5-1% below 30-year fixed rates. The trade: rate certainty for savings.
A 5/1 ARM makes sense when:
- You’re confident you’ll sell or refinance within 5 years
- The initial rate saves enough to offset the refinance costs
- You have the income to absorb a potential rate increase at adjustment
The risk: if rates are higher when your ARM adjusts and you can’t refinance (due to credit changes, home value decline, or tighter lending standards), your payment could jump 20-30%.
Historical Context
The current rate environment, while painful for buyers accustomed to 2020-2021’s sub-3% rates, is historically normal. The 50-year average for 30-year fixed rates is approximately 7.7%. The 2010-2021 period of sub-5% rates was the anomaly, driven by Federal Reserve intervention.
Waiting for rates to return to 3% is not a viable strategy. The conditions that produced those rates (near-zero federal funds rate, massive Fed balance sheet expansion, pandemic-era policy) were extraordinary and are unlikely to repeat.
What Buyers Should Do
- Focus on payment, not rate. A lower-priced home at 7% can be cheaper than a higher-priced home at 5%.
- Get pre-approved at current rates. Know your actual budget, not your wishful-thinking budget.
- Consider the total cost. HomeStats shows PITI plus maintenance, insurance, and tax for every state — not just the mortgage payment.
- Marry the house, date the rate. If you find the right home in the right market, buy it and refinance later if rates drop. But only if the numbers work at today’s rate.
HomeStats tracks the current 30-year mortgage rate on the national dashboard and uses it in every state’s affordability calculations. The income-needed-to-buy metric updates automatically as rates change.