What a 6.66% Mortgage Costs on the Median Massachusetts Home, August 2026

Freddie Mac’s Primary Mortgage Market Survey put the 30-year fixed-rate mortgage at 6.66% for the week of August 27, 2026, and the 15-year fixed at 5.98%. The Massachusetts Association of REALTORS® reported a statewide single-family median sale price of $715,000 for July 2026. That’s enough to work out what a typical purchase costs each month.

The 30-year payment

With 20% down, the loan on a $715,000 home is $572,000. Standard amortization over 360 months at 6.66% gives a monthly principal and interest payment of $3,676. That doesn’t include property tax, homeowner’s insurance, PMI (not required at 20% down) or any condo fee.

The 15-year payment

The same $572,000 loan on a 15-year fixed at 5.98% comes to $4,821 a month. Half the term, so the payment is about $1,145 higher, and the total interest paid over the life of the loan is less than half of the 30-year total.

What changes the number

• Price. Town medians in Greater Boston vary widely from the statewide figure. Newton, Brookline and Lexington sit well above it; Worcester County sits well below.
• Down payment. At 6.66%, each $10,000 of loan costs about $64 a month. Ten thousand less down adds that much to the payment.
• Your rate. The PMMS is a weekly national average. An individual quote depends on the lender, credit score, loan type and whether points are paid.
• Property tax. Most Massachusetts towns bill quarterly, and the amount depends on the town’s rate and the assessed value.

How I use this with buyers

Before touring, I run this calculation on the actual listing price and the town’s tax rate, so buyers see the real monthly number before they fall for a house. Diana Kim, REALTOR®, eXp Realty.