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Regear Calculators
Eight calculators, one job: turn "what gears for 37s?" from a forum argument into arithmetic. Every one shows its formula, and every one pre-fills from your saved rig in My Garage.
Crawl & Comparison
Crawl Ratio
The headline number every build thread quotes — first gear × low range × axle, computed from your actual transmission, not a generic chart.
Open calculator →Regear ComparisonYour current setup on the left, the setup you're dreaming about on the right — crawl, cruise RPM and speedo error, side by side.
Open calculator →Gears, Tires & Speed
Gear Ratio / RPM / MPH
RPM at any speed, speed at any RPM — for your transmission's actual gears, in high range, from your saved rig.
Open calculator →Gear & Speed TableEvery gear, both ranges, at your RPM points — the full map of your drivetrain in one table.
Open calculator →Tire Size ChangeWhat a bigger tire really does to your gearing — effective ratio, gearing lost, and the ratio that makes it stock again.
Open calculator →Restore-Stock RatioThe one-formula answer to 'what gears do I need for 35s?' — factory ratio corrected for your new tire, with the closest real-world ratios compared.
Open calculator →Speedometer CorrectionHow far off your speedometer is after tires and gears — true speed for every indicated speed, and the correction factor a programmer needs.
Open calculator →Tire DiameterSidewall numbers into real inches and revs-per-mile — the input every other gear calculation depends on.
Open calculator →Drag racing? The Garage math family's other half is RaceCombo's calculator library — ET, horsepower and density altitude for the strip.