GarageX calculators
The glovebox math, done right.
Free reference calculators for people who wrench — no account needed. Pure math, no tricks.
Tire size calculator
Enter a size like 205/55R16 to see its real dimensions — add a second size to compare fitment and speedometer effect.
Gear ratio & speed calculator
Gear ratio × final drive × tire size → road speed. See what RPM you'll turn at highway speed, or your speed at redline.
Speedometer error calculator
Your speedometer counts wheel revolutions and assumes the factory tire. Change the tire, change the truth.
Compression ratio calculator
Static CR from the volumes that matter: swept, chamber, gasket, deck, and piston.
Boost pressure converter
PSI, bar, and kPa — plus a clearly-labeled ballpark of what boost does to power.
Torque unit converter
Nm ↔ ft-lb ↔ in-lb, with a typical metric fastener guide.
Fluid capacity converter
The manual says liters, the bottle says quarts. Fixed.
Tire date code decoder
The last four digits of the DOT code are the tire's birthday. Older than it looks?