FRED · Freddie Mac PMMS + 10-Year Treasury · Updated weekly
Mortgage Spread Index
The 30-year fixed rate doesn't just track the 10-year Treasury — it runs on top of it. When that gap widens past its historical norm, it adds real monthly payment cost independent of where the Fed or the 10-year yield sit.
30-year fixed
6.67%
Aug 2026
10-year Treasury
4.63%
FRED DGS10
Spread
204 bps
+29 bps vs ~175 bps norm
What the spread costs on a $350,000 mortgage
Holding the loan amount fixed, comparing today's actual 30-year rate against what the rate would be if the spread sat at its ~175 bps historical norm instead.
At the historical-normal spread
6.38% (10-year + ~175 bps)
$2,185/mo
At today's actual spread
6.67%
$2,252/mo
+$67 vs the historical-normal spread
Principal and interest only, on an 80% LTV $350,000 loan amount. Does not include taxes, insurance, or PMI. Compare lenders at today's mortgage rates.
Methodology
- 30-year fixed rate: Freddie Mac Primary Mortgage Market Survey (PMMS) via FRED, series MORTGAGE30US, weekly.
- 10-year Treasury yield: FRED series DGS10, daily.
- The ~175 bps historical norm is a commonly cited long-run reference point for the pre-pandemic (roughly 1990–2019) average primary-secondary spread — an approximation, not a precise SwitchWize-verified figure.
- Both series are national averages. Individual quoted rates vary by credit score, LTV, and lender.
Full ranking and lender-coverage methodology at /methodology.