Why this calculator exists
On September 16, 2026 the Federal Reserve raised the federal funds rate to 3.75%–4.00%, its first hike since 2023, and the minutes released on October 7 show most officials expect another increase before year-end. Freddie Mac's 30-year average reached 7.40% on October 8, up seven weeks in a row. Everyone with a loan is asking the same question: what does the next move cost me? This page answers it with your numbers instead of a headline.
Enter the balance, the rate you have or were quoted, and the years remaining. You get the payment at the current rate and at +0.25, +0.5 and +1 point, plus what a 0.25-point drop would save if the market turns. The link and the share card carry your inputs, so you can send the exact result to a spouse, an agent or a lender.
Who it is for
- Buyers shopping now. A pre-approval is not a rate lock. If the next Fed meeting (October 27–28, 2026, then December 8–9) moves mortgage rates a quarter point, a $500,000 loan costs about $85 more a month for 30 years. Locking a rate you can afford beats guessing.
- ARM borrowers. The 5/1 and 7/1 ARMs written in 2019–2021 are resetting into a market 3–4 points higher. Enter your remaining balance and the rate you expect at reset; the +1 column is a realistic stress test.
- HELOC holders. HELOCs float with the prime rate, which is the federal funds rate plus 3 points — about 7.0% after the September hike. Your payment changes with the next statement, not next year.
| Balance (30 yrs left) | At 7.40% | +0.25 | +0.50 | +1.00 | Extra per year at +1 |
|---|---|---|---|---|---|
| $300,000 | $2,077 | $2,129 | $2,180 | $2,286 | $2,500 |
| $500,000 | $3,462 | $3,548 | $3,634 | $3,809 | $4,167 |
| $800,000 | $5,539 | $5,676 | $5,814 | $6,095 | $6,668 |
What to do with the result
If the +1 column is a number you could not carry, you have three honest options: lock a fixed rate now if you are buying, refinance an ARM into a fixed loan before the reset, or shrink the balance so the sensitivity shrinks with it. If the +1 column is uncomfortable but survivable, write the number down and set a rate alert below — the week rates fall to your target, we email you. What does not work is waiting for a Fed announcement to tell you what you can afford; the calculator already did.
For the full payment with taxes and insurance, see the Mortgage Calculator. For whether a refinance pays for itself, read the 2026 Refinancing Guide.