Somerville mortgage calculator
What a Somerville mortgage costs each month, how long it runs, what it costs in total, and how much sooner it ends if you pay a little more. Built on monthly compounding and the 30-year fixed loan, on a closing that taxes the seller rather than the buyer.
Calculator
The purchase
20.0% down. The minimum on this price is $28,289. At 20% or more there is no mortgage insurance.
A US lender qualifies you on debt-to-income rather than at a stress-test rate, so this payment is the payment. What varies is the rate you are quoted: credit score, points paid at closing and the lender itself move it by more than half a point.
The contract length, not the amortization. At the end of it you renew at whatever rates are then available.
Paying it down faster
Most lenders cap annual prepayments at 10–20% of the original principal, and charge a penalty above it. Check your own commitment before planning around a large lump sum.
Where the money goes, year by year
Early payments are almost all interest. The crossover (the year principal finally exceeds interest) is the real shape of an amortized loan, and it is much later than most people expect.
Show the first two years of the schedule
| Payment | Amount | Interest | Principal |
|---|---|---|---|
| 1 | $4,847.79 | $4,186.76 | $661.03 |
| 2 | $4,847.79 | $4,183.09 | $664.70 |
| 3 | $4,847.79 | $4,179.40 | $668.39 |
| 4 | $4,847.79 | $4,175.69 | $672.10 |
| 5 | $4,847.79 | $4,171.96 | $675.83 |
| 6 | $4,847.79 | $4,168.21 | $679.58 |
| 7 | $4,847.79 | $4,164.44 | $683.35 |
| 8 | $4,847.79 | $4,160.65 | $687.14 |
| 9 | $4,847.79 | $4,156.83 | $690.96 |
| 10 | $4,847.79 | $4,153.00 | $694.79 |
| 11 | $4,847.79 | $4,149.14 | $698.65 |
| 12 | $4,847.79 | $4,145.26 | $702.53 |
| 13 | $4,847.79 | $4,141.37 | $706.42 |
| 14 | $4,847.79 | $4,137.44 | $710.35 |
| 15 | $4,847.79 | $4,133.50 | $714.29 |
| 16 | $4,847.79 | $4,129.54 | $718.25 |
| 17 | $4,847.79 | $4,125.55 | $722.24 |
| 18 | $4,847.79 | $4,121.54 | $726.25 |
| 19 | $4,847.79 | $4,117.51 | $730.28 |
| 20 | $4,847.79 | $4,113.46 | $734.33 |
| 21 | $4,847.79 | $4,109.38 | $738.41 |
| 22 | $4,847.79 | $4,105.29 | $742.50 |
| 23 | $4,847.79 | $4,101.16 | $746.63 |
| 24 | $4,847.79 | $4,097.02 | $750.77 |
Derived from the figures above, not a lender's statement. A real schedule also depends on your closing date and the lender's rounding.
An estimate from published figures, not a lender quote.
What the lender will escrow beside the payment
Principal and interest is what this calculator computes. On the typical Somerville house your lender will escrow roughly $481 a month in property tax, which is the 0.61% an owner-occupier really pays out of the $10.98 per $1,000 the municipality publishes, and it assumes you have filed for the residential exemption. Before you file, or in the first year if you did not own and occupy on the previous 1 January, the escrow is $863 a month instead. Add about $155 a month in homeowners insurance.
Massachusetts taxes the deed, and the seller pays it
Massachusetts charges a buyer nothing to take title and nothing to borrow. There is no buyer transfer tax, no mortgage recording tax and no intangible tax on the loan. The only tax on the transaction is the deeds excise at $4.56 per $1,000, and MGL c.64D s.1 puts that on the seller. On this house that is $4,300, and it is the seller's by statute rather than by convention, so unlike Florida's documentary stamp it is not negotiable in principle either. If you are arriving from the Florida pages on this site, that is the column that is missing: there a buyer pays a documentary stamp on the promissory note and a non-recurring intangible tax on the mortgage, together about 0.55% of whatever is borrowed, and both get larger the less you put down. Here the buyer's side is the attorney, the title policy, the inspection and the registry recording, and none of it moves with the loan.
PMI is the number to watch, not the rate
Below 20% down the lender adds private mortgage insurance, which insures the lender rather than you. Federal law makes them terminate it once the scheduled balance first reaches 78% of the purchase price, and you can ask for cancellation at 80% if you are current. The calculator shows the exact month rather than averaging the premium across the loan, and the month moves when you add extra principal, because the trigger is the amortization schedule rather than what the house is worth. Worth knowing in Massachusetts specifically: the ONE Mortgage program run by the Massachusetts Housing Partnership requires 3% down and carries no private mortgage insurance at all, which on a Greater Boston price is worth more than most down payment grants.
Monthly compounding, and why the Canadian number would be wrong
An American fixed-rate mortgage compounds monthly: the periodic rate is the annual rate divided by twelve. Canadian mortgages compound twice a year, which makes the same nominal rate slightly cheaper. This site runs both conventions and no page borrows the other country's arithmetic.
What this cannot tell you
None of this includes the Community Preservation Act surcharge. The CPA is a local option under MGL c.44B, adopted by ballot, that adds a surcharge of 1% to 3% to the property tax bill to fund open space, historic preservation and affordable housing, usually with the first $100,000 of value exempted. It is levied on the bill rather than on the value, so it is in no published rate and in no figure on this page, and it is adopted in a good many of these municipalities. Check whether the town has it and at what percentage before you treat the tax line here as the whole tax line. It also cannot see a Proposition 2 1/2 override or debt exclusion, which raises the levy limit permanently and lands on the escrow with no change to any rate on this page. And it cannot tell you what an insurer will quote on the specific structure, which on housing stock largely built between 1890 and 1940 turns on the roof, the heating system, the electrical service and whether the building has ever been deleaded. For the full comparison against renting, use the rent versus buy calculator.
Sources
- Tax Rates by Class, fiscal year 2026 · Massachusetts Department of Revenue, Division of Local Services, Municipal Databank · retrieved Supports: The certified fiscal 2026 residential rate for each of the twenty-four municipalities, from Cambridge at $6.67 to Everett at $12.62, The commercial, industrial and personal property rate behind each of them, which gives the classification shift, That Arlington and Belmont charge a single rate to all classes, That fiscal 2026 is the most recent fully certified year: at the retrieval date only two of the state's 352 municipalities had a fiscal 2027 rate on the table
- Residential exemption, fiscal year 2026 · City of Boston Assessing Department · retrieved Supports: $351,108 of assessed value excluded from an owner-occupied parcel, worth $4,353.74 at the city's $12.40 rate, The 1 April filing deadline and the requirement to have owned and occupied on the previous 1 January
- City of Somerville FY2026 Classification Hearing, 25 November 2025, and the FY2026 Property Tax Update · Somerville Board of Assessors · retrieved Supports: A residential exemption of 35% of average assessed value adopted for fiscal 2026, yielding savings of up to $4,578, A minimum residential factor of 82.816, the legal minimum for the city, Form LA-4 parcel counts and assessed values by use code, from which the average Class One value of about $1,191,000 follows, That Somerville carries 7,251 condominium parcels against 2,315 single-family parcels, That life science property in this market depreciated about 20% between fiscal 2025 and fiscal 2026
- City Council meeting minutes, 28 October 2025: adoption of a residential exemption and minimum residential factor for fiscal 2026 · City of Malden · retrieved Supports: A unanimous vote to adopt a residential factor of 0.9054 and a residential exemption of 35%, raised from 30%, The council's own statement on the record that the increase is a tax shift benefiting owner-occupied households and not a tax cut, and that the shift is budget neutral, Average fiscal 2026 values of $449,000 for a condominium, $666,000 for a single family, $861,000 for a two-family and $991,000 for a three-family, That the increase from 30% to 35% is worth about $291 a year, from which the $178,684 exemption value here is derived, A Proposition 2 1/2 override under discussion for fiscal 2027 at $5.4 million and $8.2 million
- Residential exemption information for fiscal year 2026 · City of Chelsea Board of Assessors · retrieved Supports: An exemption of 35% of the average assessed value of all Class One residential parcels, $279,066 of assessed value excluded for fiscal 2026, worth $3,203.68 at the city's $11.48 rate, The 1 April 2026 filing deadline and the 1 January ownership and occupancy test
- Residential exemption information, fiscal year 2026 · City known as the Town of Watertown, Assessing Department · retrieved Supports: The maximum 35% exemption recommended by the assessors and adopted by the council for fiscal 2026, $324,715 of assessed value excluded, worth $3,961.52 at the town's $12.20 rate
- Residential exemptions · Town of Brookline Assessors · retrieved Supports: $354,974 deducted from a qualified owner-occupier's assessed value for fiscal 2026, That the exemption may be not more than 35% of the average assessed value of all Class One residential parcels and that the amount changes each year
- Assessor's Department: the residential exemption · City of Waltham · retrieved Supports: $317,643 of assessed value removed from an owner-occupied residence of up to three units for fiscal 2026, The maximum 35% exemption continued by the city council, The 1 January 2025 ownership and occupancy test for the fiscal 2026 year
- Assessor's office: owner-occupant residential exemption, fiscal year 2026 · City of Everett · retrieved Supports: $204,651 of taxable value removed from an owner-occupied parcel, worth $2,582.70 at the city's $12.62 rate
- Residential exemption and fiscal 2026 tax rates · City of Cambridge Assessing Department · retrieved Supports: A 30% residential exemption for fiscal 2026, $510,208 of assessed value, worth about $3,403, A residential rate of $6.67 per $1,000 set by the city council on 20 October 2025, the lowest in the Commonwealth
- Zillow Home Value Index (ZHVI), mid-tier, smoothed and seasonally adjusted: city files for all homes, single family and condominium, June 2026 · Zillow Research · retrieved Supports: A typical home value for each municipality, computed on one method across all twenty-four, The same series and month the Charlotte, Orlando, Palm Beach, Miami and Tampa Bay pages use, A separate single-family and condominium index for every one of these municipalities, Year-over-year change to June 2026, which is negative in three of the twenty-four
- Zillow Observed Rent Index (ZORI), all homes, smoothed: city file, June 2026 · Zillow Research · retrieved Supports: Asking rents for all twenty-four municipalities, with no gaps and therefore no fallback anywhere in this layer
- Fiscal Year 2026 Fair Market Rents: Boston-Cambridge-Quincy, MA-NH HUD Metro FMR Area · United States Department of Housing and Urban Development · retrieved Supports: $2,476 for one bedroom, $2,941 for two and $3,526 for three, The ratios this layer uses to split the Zillow rent index by bedroom count, which differ from the Florida layers'
- Annual estimates of the resident population for minor civil divisions, 2020 to 2024 · United States Census Bureau, Population Estimates Program · retrieved Supports: 2020 census counts and 2024 estimates for each municipality, at summary level 061, That in New England the municipality is the minor civil division, so 061 rather than the place level is the right series and all 351 Massachusetts municipalities appear in it, Boston at 673,458 and Cambridge at 121,186; Belmont at 27,442 as the smallest here, Weymouth at 60,159, which would rank eleventh on this table and is outside the eleven-mile rule by three tenths of a mile
- Primary Mortgage Market Survey, 27 August 2026 · Freddie Mac · retrieved Supports: A 30-year fixed-rate mortgage averaging 6.66%
- Average home insurance cost in Massachusetts, 2026 · MoneyGeek and Insurance.com, on carrier rate filings · retrieved Supports: A Massachusetts average between roughly $1,500 and $1,900 a year against a national average near $2,800, Coastal communities running roughly a third to two thirds above the state mean, Wind and hurricane deductibles on coastal policies of 1% to 5% of dwelling value rather than a flat amount
- Chapter 59, Section 5C: residential exemption · Massachusetts General Laws · retrieved Supports: A local option exemption of not more than 35% of the average assessed value of all Class One residential parcels, The exemption applies only to a parcel that is the principal residence of the taxpayer as of 1 January, The percentage is voted annually by the municipality
- Chapter 59, Section 21C: Proposition 2 1/2 · Massachusetts General Laws · retrieved Supports: A levy ceiling of 2.5% of the total full and fair cash value of taxable property, A levy limit that may grow 2.5% a year plus certified new growth, Overrides and debt exclusions as the two ways a municipality exceeds the limit, That the cap is on the levy and not on the tax rate
- Chapter 59, Section 38: valuation at full and fair cash value · Massachusetts General Laws · retrieved Supports: Assessment at full and fair cash value, re-set annually rather than frozen at a base year, No purchase reset and no growth cap on an assessment, so a seller's bill is a fair guide to a buyer's
- Chapter 40, Section 56: classification and the minimum residential factor · Massachusetts General Laws · retrieved Supports: The power to shift part of the levy onto commercial, industrial and personal property, A ceiling of 175% of the commercial share, subject to a minimum residential factor, That the published residential rate is therefore an output of a local vote rather than a measure of what a town spends
- Chapter 64D, Section 1: excise upon deeds, instruments and writings · Massachusetts General Laws · retrieved Supports: $2.28 for each $500 of consideration, which is $4.56 per $1,000 or 0.456%, The excise falls on the person making the deed, so it is the seller's by statute, The Barnstable County rate of $2.85 per $500, which no municipality in this layer pays
- Chapter 40P: the Massachusetts Rent Control Prohibition Act · Massachusetts General Laws · retrieved Supports: No city or town may enact or enforce any control on the rent of residential property, Enacted by the 1994 ballot initiative and effective 1 January 1995, The voiding of the then-existing ordinances in Boston, Cambridge and Brookline
- Chapter 188: the declaration of homestead · Massachusetts General Laws · retrieved Supports: Protection of up to $500,000 of equity in a principal residence from most creditors on a declared homestead, and $125,000 automatically, That this is a creditor protection and not a property tax exemption, which is the confusion the caveat in lib/housing/massachusetts.ts exists to prevent
- Real Estate Bar Association for Massachusetts v. National Real Estate Information Services, 459 Mass. 512 · Supreme Judicial Court of Massachusetts · retrieved Supports: That conducting a residential real estate closing in Massachusetts is the practice of law and must be done by an attorney
- Homebuyer programs and down payment assistance · MassHousing · retrieved Supports: Down payment assistance to $30,000 generally and to $50,000 or 10% of price in Boston and the Gateway Cities
- ONE Mortgage · Massachusetts Housing Partnership · retrieved Supports: A 3% down first mortgage with no private mortgage insurance for income-eligible first-time buyers
These are estimates built from published figures, not a lender quote, a pre-approval or financial advice. Rates, premiums and state and federal rules change; confirm anything you plan to act on with a mortgage professional and read the sourcing methodology.