What this tool does
The cheapest commute is rarely obvious because driving costs hide behind fuel, parking, depreciation, and maintenance. This calculator compares Baltimore’s MTA monthly pass (about $90) against the true cost of driving, using local gas prices, your fuel economy, downtown parking (around $120/mo), and the IRS per-mile operating rate that captures full vehicle cost.
How it works
First the tool computes monthly driving mileage, then both a fuel-only and an all-in cost:
monthly_miles = one_way_miles * 2 * commute_days
fuel_cost = (monthly_miles / mpg) * gas_price
allin_cost = monthly_miles * irs_rate_per_mile + parking
transit_cost = monthly_pass
The IRS standard mileage rate (about $0.70/mile) bundles fuel, depreciation, insurance, and maintenance, so the all-in figure is a fairer comparison than fuel alone. The tool flags whichever option — transit or driving — costs less per month.
Example and notes
For a 12-mile one-way commute, 20 days/month: monthly_miles = 12 * 2 * 20 = 480. At 28 mpg and $3.40/gal, fuel-only is (480 / 28) * 3.40 ≈ $58.3. All-in at $0.70/mile plus $120 parking is 480 * 0.70 + 120 = $456. Against a $90 transit pass, driving costs roughly $366/mo more once you count depreciation and parking. If you can avoid paid parking, the gap narrows sharply — adjust the parking input to model your real situation.