What this calculator does
The Boston mortgage calculator estimates your full monthly housing payment — principal and interest plus property tax, homeowners insurance, HOA or condo fees and PMI — using Boston defaults. It also shows total interest over the loan and how the balance falls over time.
How to use it
- Enter the price and down payment.
- Enter the interest rate and choose the loan term.
- Check the local property tax rate, insurance and HOA defaults; replace them with the listing's numbers if you have them.
- Leave the PMI rate in place if you are putting down less than 20%.
- Compare 15- and 30-year terms to see the trade-off between payment and total interest.
The formula
Principal and interest = L × r ÷ (1 − (1 + r)^−n), where L is the loan, r the monthly rate (annual rate ÷ 12) and n the number of payments. Property tax = price × rate ÷ 12. Insurance = yearly premium ÷ 12. PMI = loan × PMI rate ÷ 12 when the down payment is under 20%.
Worked example for Boston
A $800,000 home with 20% down at 6.5% for 30 years:
| Payment part | Monthly | Yearly |
|---|---|---|
| Principal and interest | $4,045 | $48,543 |
| Property tax | $827 | $9,920 |
| Homeowners insurance | $267 | $3,200 |
| HOA / condo fees | $500 | $6,000 |
| Private mortgage insurance | $0 | $0 |
| Total | $5,639 | $67,663 |
Estimated monthly payment: $5,639.
What makes Boston payments different
Boston's FY2026 residential tax rate is $12.40 per $1,000 of assessed value. Owner-occupants can claim the residential exemption, worth up to $4,353.74 in FY2026, which removes a flat amount of value from the bill.
Insurance in Boston is usually a smaller line than property tax, but get a quote for the specific home.
Common mistakes and tips
- Budgeting from principal and interest alone.
- Forgetting that property tax is reassessed and insurance renews every year, so escrow payments change.
- Not asking for the HOA's budget and reserve study before buying a condo.
- Paying PMI longer than needed — on conventional loans it can usually be removed at 20% equity.
Frequently asked questions
What is the monthly payment on a $800,000 home in Boston?
With 20% down at 6.5% for 30 years and Boston defaults for tax, insurance and HOA, about $5,639 a month.
What does PITI mean?
Principal, interest, taxes and insurance — the four parts of a typical mortgage payment collected through escrow. HOA dues and PMI are added on top.
Is a 15-year mortgage worth it?
A 15-year loan has a higher payment but usually a lower rate and far less total interest. The right choice depends on cash flow and other goals.
Where do the Boston property tax defaults come from?
They are Rate and Reason's rough effective rate for Boston, based on the rules in the Boston property tax calculator. Check the actual bill for any home you are considering.
Sources
Disclaimer
This calculator provides estimates for educational purposes only and is not financial, tax, legal, real estate, or insurance advice. Consult a licensed professional before making decisions.