Automotive
Car and engine calculators for drivers and gearheads: gear ratios, gas mileage, engine displacement, tire size, power to weight and compression ratio, with the math shown.
Compression Ratio Calculator
Calculate static compression ratio from swept and clearance volume, or from bore and stroke. Enter chamber cc to get your CR. Free engine CR calculator.
Engine Displacement Calculator
Calculate total engine displacement from bore, stroke and cylinder count. Get the result in cc, litres and cubic inches. Free engine size calculator.
Gas Mileage Calculator
Calculate gas mileage in MPG or L/100km from distance and fuel used, plus trip fuel cost and cost per mile. Supports US and metric. Free MPG calculator.
Gear Ratio Calculator
Find your axle or gear ratio from ring and pinion teeth, then get wheel rpm and road speed from tire size and engine rpm. Free gear ratio calculator.
Power to Weight Ratio Calculator
Calculate power to weight ratio in hp per pound, hp per ton, watts per kg and kW per tonne. Enter horsepower or kW with pounds or kg. Free tool.
Tire Size Calculator
Read a tire size like 225/45R17 to get sidewall height, overall diameter, circumference and revs per mile, and compare two sizes for speedometer error.