// Free tuning tools
Performance,
dialed in.
Fast, ad-free calculators for people who actually turn the wrenches — then a build planner to spec your car and share it. No sign-up, no fluff, works on your phone in the garage.
Instant
Everything runs in your browser — no waiting, no accounts, results update as you type.
Ad-free & free
No pop-ups, no trackers fighting for your attention. Just clean, fast tools.
Made for the garage
Works great on a phone with greasy thumbs. Built by enthusiasts, for enthusiasts.
Tire Size Calculator
Compare two tire sizes — diameter change, sidewall, circumference & speedometer error.
LiveWheel Offset & Fitment
ET / offset, backspacing and poke — check if a wheel clears.
LiveGear Ratio & Speed
Speed per RPM in every gear, final-drive swaps and rev-drop.
LivePower-to-Weight
hp/ton, kg/hp and where your build really stacks up.
LiveHP ↔ kW Converter
Horsepower, kilowatts and PS — converted cleanly.
Live0–60 & ¼-Mile Estimator
Estimate acceleration from power and weight.
LiveBoost & Compression
Effective compression, pressure ratio and density.
LiveFuel Cost & Economy
Cost per trip, L/100km ↔ MPG and running costs.
LiveCompression Ratio
Static CR from bore, stroke, chamber, gasket & deck.
LiveEngine Displacement
cc, litres & cubic inches from bore, stroke & cylinders.
LiveMean Piston Speed
m/s & ft/min from stroke and RPM — the reliability read.
LiveAFR ↔ Lambda
Air-fuel ratio ↔ lambda per fuel, with tuning targets.
LiveE85 Mix
Blend two fuels to a target ethanol % — exact volumes.
LiveInjector Size
Required cc/min & lb/hr plus fuel pump LPH from target hp.
LiveDyno Correction
SAE J1349 correction factor from temp, pressure & humidity.
LiveDensity Altitude
Air density, density altitude & NA power loss for the day.
LiveGearbox Designer
Sawtooth speed/RPM chart, top speed per gear & shift rev-drops.
LiveOBD-II Code Lookup
Search 1,100+ legacy P0 definitions with verification status.
Start with the tire size calculator
The most-used tool — diameter, gearing and speedo error in one screen.