Two machines, different bills
A car carries insurance, registration, parking, wear, and fuel. A bike mostly asks for tubes, tires, and occasional service. The table below is qualitative. Dollar cells are reminders, not quotes from your garage.
| Topic | Car | Bike |
|---|---|---|
| Fuel or food | Gasoline scales with miles and MPG. | You eat more when you ride hard. We do not add food cost here. |
| Fixed yearly items | Insurance, registration, part of depreciation, parking in many cities. | Small maintenance budget unless you race or replace gear often. |
| Time cost | Often faster door to door on long routes. | Slower on paper, doubles as exercise minutes. |
| Weather | Heater, wipers, dry seats. | Rain gear, lights, planning. No shame in skipping ice days. |
If you want a broader environmental picture beyond the commute line, pair this page with the carbon footprint calculator or the meat footprint calculator. Each tool stresses a different slice of daily choices.
Where every dollar in the car column comes from
We multiply your round-trip miles by work days, assume fifty work weeks, and split car cost into fuel plus six flat annual buckets. Fuel uses your MPG and gas price. Insurance sits at fifteen hundred dollars, maintenance at one thousand, registration at two hundred, depreciation at three thousand, parking at twelve hundred. Those figures are middle guesses for the United States. Your county, credit score, garage deal, and car age will move them a lot.
Bike upkeep is a single two-hundred-fifty dollar bucket. It hides new chains, brake pads, and a rare wheel true. It ignores the purchase price of the frame. If you want a purchase decision tree instead of commute math, open the decision maker tool and write your own criteria.
For time, we divide round-trip miles by each speed and convert to minutes. Rush hour, school zones, and ebike assist are not modeled. Treat the clock rows as a starting sketch before you rearrange your morning with the time blocking tool.
Tuesday in the suburbs, Thursday downtown
Jamie, 3.4 miles each way, five days. Low fuel burn, short clock penalty on the bike, big fixed car costs still show up. Cycling most days saves money fast unless parking is free and insurance is unusually cheap.
Ravi, 11 miles each way, hybrid office three days. Bike time grows. An ebike trims minutes without erasing exercise. Annual miles still pile up for CO₂ on car days. Worth logging how many hours you truly spend behind the wheel. If screen time eats your evening, compare against the social media time calculator to see where hours actually go.
Aisha, 22 miles each way, five days. Pure time math favors a motor. Some people still mix train plus bike, or drive partway and ride the last stretch. This sheet does not score mixed mode. You would need to split distances by hand.
The honesty clause
Results are estimates. Emissions per mile vary by engine, maintenance, and how hard you accelerate. CO₂ from food for a hungry cyclist is real. We set operational bike emissions to zero to keep the story simple. Fixed car dollars are static. They will be wrong for you. That is the point. Use the tool to ask what happens if gas jumps twenty cents or if you only drive three days a week.
We recommend you copy our outputs into your own spreadsheet if you are negotiating a benefits package or buying a second vehicle. Employers and insurers use different rules.
No server, no trip log
Numbers you type stay in this tab. We do not store routes, addresses, or totals on a server. Clearing the tab wipes the session.
