Calculators for cars, trucks, trailers, motorcycles and bikes
Tires and wheels, gearing, engine building, towing, fuel and EV, motorcycles and bicycles: work out the numbers before you buy or build. Every tool shows its formula, and everything runs in your browser.
Tires and wheels
Tire size
Tire size calculatorDiameter, width, sidewall and revolutions from any size codeTire size comparisonTwo or three sizes side by side, with the speedometer effectTire size chartOverall diameter for every width and aspect ratio on a rimTire size converterMetric to inch sizes and back, with the closest matchesPlus size tire calculatorBigger or smaller rims, same overall tire height
Tire markings
Tire sidewall decoderType what is on your tire, see every marking explainedTire date codeWeek, year and age from the DOT code on the sidewallTire speed rating chartEvery speed letter from A1 to Y, in mph and km/hTire load index chartLoad index to lb and kg, XL and LT load rangesUTQG ratingTreadwear, traction and temperature grades, one tire or twoLT vs P tiresLoad per tire and size of a P-metric and an LT tire, side by side
Wheels
Backspacing calculatorOffset in mm to backspacing in inches, and backWheel offset calculatorCurrent vs new wheel: poke, inner clearance and track widthBolt pattern calculatorMeasure the studs, get the bolt circle in mm and inchesWheel spacer calculatorSpacer thickness to effective offset, backspacing and poke
Speed and braking
VIN decoder
VIN decoderYear, make, model and engine from the 17-character VINFord VIN decoderFord and Lincoln engine, plant and model codes from the VINChevy VIN decoderChevrolet engine, plant and model codes from the VINGM VIN decoderGMC, Buick and Cadillac codes from the VINJeep VIN decoderWrangler, Gladiator and Grand Cherokee codes from the VINRam VIN decoderRam 1500, HD and ProMaster codes from the VINDodge VIN decoderCharger, Durango and Pacifica codes from the VINToyota VIN decoderToyota and Lexus model, engine and plant codes from the VINHonda VIN decoderHonda and Acura trim, engine and plant codes from the VINMercedes VIN decoderMercedes-Benz, Maybach and Sprinter codes from the VINBMW VIN decoderBMW and MINI model, engine and restraint codes from the VINTesla VIN decoderModel 3, Y, S, X and Cybertruck codes from the VINNissan VIN decoderNissan and Infiniti engine, body and plant codes from the VINHyundai VIN decoderHyundai and Genesis series, engine and plant codes from the VINKia VIN decoderKia trim, engine, airbag and plant codes from the VINSubaru VIN decoderSubaru engine, trim, airbag and plant codes from the VINMazda VIN decoderMazda carline, trim, engine and plant codes from the VINMitsubishi VIN decoderOutlander and Eclipse Cross codes from the VINVW VIN decoderVolkswagen series, engine and model codes from the VINAudi VIN decoderAudi series, engine and model codes from the VINPorsche VIN decoder911, Cayenne, Macan, Taycan and Panamera codes from the VINVolvo VIN decoderVolvo and Polestar engine, trim and series codes from the VINLand Rover VIN decoderRange Rover, Defender and Jaguar codes from the VIN
Gearing
Engine
Engine size and compression
Engine displacementBore, stroke and cylinders to cc, liters and cubic inchescc to cubic inchesConvert cc, cubic inches and liters both waysCompression ratioStatic CR from bore, stroke, chamber, piston, gasket and deckDynamic compressionEffective compression from the intake valve closing point and rod lengthRod ratioRod length to stroke, piston motion chart, peak piston speed and accelerationPiston speedMean piston speed in ft/min and m/s from stroke and rpmBMEPBrake mean effective pressure in psi, bar and kPa from torque or power
Power and performance
Horsepower calculatorTorque and rpm to horsepower and back, in hp, kW and PSWheel horsepowerCrank hp to wheel hp and back, with a loss you choosePower to weight ratiolb per hp, hp per ton, kg per kW and kW per tonne from one pair of numbersQuarter mileEstimated ET and trap speed from weight and horsepower, or horsepower from a time slip
Fuel and air
Fuel injector sizeInjector flow in lb/hr and cc/min for a power target, plus pressure and unit changesFuel pump sizeFuel flow a pump must deliver for your power, in lb/hr, gal/hr and L/hrCarburetor CFMThe airflow an engine pulls at max rpm, to size a carb in cfmVolumetric efficiencyVE in percent from measured cfm or a MAF log in g/sAir fuel ratioLambda to AFR and back for gasoline, E85, ethanol, methanol and propaneE85 mixGallons of E85 and pump gas to add for E30, E50 or any ethanol blendOctane mixApproximate octane of two fuels mixed, and how much of each for a target
Turbo and boost
Towing
Towing calculatorEvery rating you enter, how much is used, and which one you hit firstPayload calculatorHow much payload is left after people, cargo, accessories and the tongueTongue weight calculatorTongue weight as a percentage, and how to weigh it with a bathroom scaleTrailer weight calculatorDry weight plus water, propane and gear, against the trailer GVWRAxle weight calculatorWhere a load sits changes which axle carries it: see front and rearBridge law calculatorThe Federal Bridge Formula for any axle group, with a full tableTrailer tire size chartST size codes decoded: height, width and revs per mileHitch drop calculatorTwo tape measurements to the ball mount drop or rise
Motorcycle
Motorcycle gear ratioSprocket swap: final drive ratio, speed change and speed in each gearMotorcycle tire size calculatorStock vs new front and rear, with the speedometer effectChain lengthLinks needed for your sprockets and axle position, any chain sizeSag calculatorStatic and rider sag, front and rear, from three measurementsRake and trailTrail from rake, fork offset and front tire, two setups comparedPremix calculatorTwo stroke oil for any amount of fuel and any mix ratio
Bicycle
Bike gear calculatorGear inches, meters of development and gain ratio for every chainring and cogBike speed and cadenceSpeed from cadence and gear, the cadence for a target speed, and a speed chartCycling power calculatorWatts for a speed, speed for your watts, and where the power goesWatts per kg calculatorYour W/kg from power and weight, and what a target W/kg would takeE-bike range calculatorMiles or km per charge from battery Wh (or V × Ah) and your consumptionSpoke length calculatorLeft and right spoke lengths from ERD, flange sizes and cross patternBike tire size chartDecode 700x28c, 29x2.2 or 26 x 1 3/8 into the ETRTO size and bead seat
Fuel
Fuel cost calculatorWhat a drive or road trip costs in gas, split between ridersMPG calculatorYour real gas mileage from one fill-up, in every unitEV vs gas calculatorYearly fuel and charging cost of a gas car against an electric oneMPGe calculatorConvert kWh per 100 miles to MPGe, mi/kWh and metric unitsEV charging time calculatorHours to charge, kWh from the grid and cost, from your battery and chargerEV range calculatorMiles from battery kWh and efficiency, with a what-if for worse conditions