Auto calculators
Thinking about bigger tires or new wheels? These calculators turn size codes into real dimensions, compare two sizes to scale, show how far off your speedometer will read, and work out backspacing and the axle ratio that restores your original RPM.
Tire Size Calculator
Diameter, width, sidewall and revs per mile from any size code.
Open calculator →Tire Size Comparison Calculator
Two sizes side by side, to scale, with speedometer difference.
Open calculator →Tire Size Converter (Metric ↔ Inch)
Metric to inch (flotation) and back, with closest matches.
Open calculator →Speedometer Error Calculator
Your true speed and odometer error after a tire change.
Open calculator →Wheel Offset & Backspacing Calculator
Offset to backspacing, and how far a new wheel pokes out.
Open calculator →Gear Ratio & Tire Size Calculator
RPM at speed and the axle ratio to regear after bigger tires.
Open calculator →Tire guides
More calculators
Coast FIRE Calculator
See how much you need invested now to stop saving and let growth do the rest.
Open calculator →FIRE Calculator
Your financial independence number and the years it takes to reach it.
Open calculator →Mortgage Recast Calculator
New payment, interest saved and fee payback after a lump-sum recast.
Open calculator →Social Security Break-Even Calculator
Find the age where delaying Social Security pays off, e.g. 62 vs 70.
Open calculator →Gravel Calculator
Cubic yards and tons of gravel for a driveway, path or patio base.
Open calculator →Mulch Calculator
How many bags or cubic yards of mulch your beds need.
Open calculator →Pool Volume Calculator
Gallons and liters for rectangular, round, oval and kidney pools.
Open calculator →Zone 2 Heart Rate Calculator
Your easy aerobic heart rate range, plus all five training zones.
Open calculator →Barista FIRE Calculator
The smaller nest egg you need when part-time work covers some bills.
Open calculator →401(k) Match Calculator
Your employer match and the rate you need to get all of it.
Open calculator →Net Worth Percentile Calculator
Where your net worth ranks among U.S. households your age.
Open calculator →Life Expectancy Calculator
Average years remaining and your odds of reaching 80, 90 or 100.
Open calculator →Pool Chlorine Calculator
How much liquid chlorine, bleach or granules to add for your target ppm.
Open calculator →Paver Calculator
Pavers to buy, plus the gravel base and sand underneath.
Open calculator →Topsoil Calculator
Cubic yards, tons or bags of topsoil for lawns and beds.
Open calculator →Fence Calculator
Posts, pickets, rails and concrete bags for a wood fence.
Open calculator →Army AFT Score Calculator
Points for all five AFT events and pass/fail, from the official tables.
Open calculator →Max Heart Rate Calculator
Your estimated max heart rate from five formulas, plus training zones.
Open calculator →VO2 Max Calculator
Estimate VO2 max from a run, a walk test or your heart rate.
Open calculator →