Auto & Travel Calculators
Cars raise two kinds of money questions: small recurring ones (what will this trip cost, what is a fair fuel split?) and large occasional ones (how much car can I afford?). These calculators answer both, in US and metric units, with the context dealerships and fuel apps leave out.
All auto & travel calculators
The true cost of driving
Fuel is the visible cost of driving, but it is usually only about a third of the real per-mile cost once depreciation, insurance, tires and servicing are counted. That is why official mileage-reimbursement rates run several times the fuel cost. It matters when splitting trip costs (a small margin over fuel is fair) and when judging affordability, where the loan payment is only the start. The 20/4/10 rule (20% down, a 4-year loan, all car costs under 10% of gross income) works because it forces the full cost into view.
The cheapest lever is the vehicle itself. The difference between a 20 mpg and a 40 mpg car is roughly $1,000 a year in fuel at average mileage and prices. Run the numbers before the purchase, not after.
Frequently asked questions
How do I estimate fuel cost for a trip?
Divide the distance by your car's mpg to get gallons, then multiply by the price per gallon. In metric: distance × L/100km ÷ 100 × price per liter. The fuel cost calculator does both and splits the total per person.
How much should I spend on a car?
Common guidance keeps all car costs (payment, insurance, fuel, maintenance) under 10–15% of income. The car affordability calculator turns the monthly payment that fits your budget into a maximum car price at your loan rate and term.
Why is my real fuel economy worse than advertised?
Official figures come from standardized lab tests. Real traffic, speeds above 70 mph, cold starts, roof racks and cargo typically cost 10–20%. Your car's long-term average readout is the best number to plan with.