Why use the IRS mileage rate instead of just gas?

Gas alone ignores depreciation, maintenance, tires, and insurance wear. The IRS standard mileage rate (about $0.67 per mile) bundles all of these into one figure, giving a far more honest cost of driving than fuel cost alone.

What does an MBTA pass cost?

A monthly MBTA pass for local bus and subway service runs around $90. Commuter rail zones cost more. The tool lets you adjust the pass price to match your specific zone or pass type.

Should I count parking?

Yes, if you pay for it. Downtown Boston parking can run $300 a month or more, which often makes driving far more expensive than transit. Set parking to zero if your employer provides free spaces.

How are monthly costs computed?

Round-trip miles equal twice your one-way distance, multiplied by commuting days per month. The tool multiplies that by either fuel-only cost (distance / MPG times gas price) or the full IRS rate, then adds parking.

Does this include time value?

No. This calculator compares only out-of-pocket and depreciation costs. If your time matters, factor in the difference in commute duration separately — transit may be slower or faster than driving depending on your route.

Boston Commute Cost Calculator

Boston commuters often assume driving is cheap because they only count gas. Once you add parking and the real wear on your car, transit frequently wins. This tool compares the full monthly cost of driving against an MBTA pass so you can see the honest difference.

How it works

Monthly round-trip distance is twice your one-way miles times your commuting days. Driving cost can be computed two ways:

round_trip_miles = one_way_miles * 2 * days_per_month

# Fuel only:
fuel_cost = round_trip_miles / mpg * gas_price

# IRS full rate (recommended):
full_cost = round_trip_miles * irs_rate    (~$0.67/mile)

driving_total = chosen_cost + monthly_parking
transit_total = mbta_pass

The IRS standard mileage rate is recommended because it captures fuel, depreciation, maintenance, and insurance wear in one number. The tool then compares driving_total against transit_total and reports the cheaper option.

Tips and example

Say you drive 12 miles one way, 22 days a month — that is 528 round-trip miles. At the IRS rate of $0.67 that is about $354, and adding $300 of downtown parking brings driving to roughly $654 a month. An MBTA pass at $90 is dramatically cheaper. Even on fuel alone, a 30-MPG car at $3.40 gas costs about $60 in fuel plus parking. Adjust the parking field — free workplace parking changes the math substantially.