Nonlinear amplification of rate changes on affordability
A 1 percent increase in mortgage rate reduces the purchase price a given buyer can afford by roughly 10 percent. This disproportionate impact stems from the mechanics of loan payments. A buyer with $150,000 annual income and 28 percent debt limit can afford roughly $600,000 at 5 percent rates but only $540,000 at 6 percent. The rate increase of one percentage point eliminates $60,000 purchasing power.
The nonlinearity deepens as rates rise. Each successive 1 percent increase cuts affordability more sharply because the interest portion of the payment grows exponentially. At 8 percent rates, our buyer might afford only $480,000 - another $60,000 loss from 6 to 8 percent.
Market and personal implications of rate sensitivity
Rate changes reshape real estate markets. When rates rise from 5 to 7 percent, the pool of buyers who can afford a given home shrinks. Home prices often decline in the months following rate increases because supply increases (more sellers list, hoping for lower-rate refinances) and demand falls (fewer buyers can qualify). Conversely, rate cuts trigger rapid price appreciation.
For the individual buyer, rate timing matters enormously but is unpredictable. Locking a rate at 6 percent when the trajectory is toward 7-8 percent saves hundreds of thousands over 30 years. Waiting for a rate drop that never materializes costs significantly. Buyers planning to stay long-term should consider rate locks; those who might sell or refinance within 5-7 years are less vulnerable to rate risk.