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Free Automotive Tools

Decode your VIN, then build - chassis & engine codes, tire sizing, boost math, gear ratios, injector flow, and more. No login, no charge, always free.

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VIN Decoder
Start with your VIN - full specs, equipment, recall campaigns, and the chassis & engine codes enthusiasts actually use.
Start Here
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Tire Size & Speedometer Correction
Compare tire sizes with a visual diagram, speedo error table, AWD safety check, and staggered front/rear mode.
Most Popular
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Datalog Analyzer
Drop in an MHD, JB4, bm3, or EcuTek CSV log. Finds your WOT pulls and grades knock, boost vs target, AFR, IATs, trims, and fuel pressure.
New
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Wheel Offset Calculator
Compare wheel width and offset (ET) to see exactly how much further a new wheel pokes out or tucks in.
Fitment
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Bolt Pattern & Hub Bore Checker
Will those wheels bolt on? Check PCD and center bore against your car, with hub-centric ring sizing.
Fitment
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0-60 & Quarter Mile Estimator
Estimate 0-60, quarter-mile ET, and trap speed from power and weight - or horsepower from a trap speed.
Drag Math
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E85 Blend Calculator
Calculate exactly how much E85 and pump gas to add at the pump to hit your target ethanol blend.
Flex Fuel
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Octane Blend Calculator
Mix race gas with pump gas - find the mix octane, or how much race fuel hits your target rating.
Race Fuel
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Dyno Correction Factor
Normalize dyno numbers to SAE or STD reference weather - compare pulls across days, dynos, and seasons.
Dyno Math
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Dyno Sheet Interpreter
Just got dyno'd? Sanity-check the sheet: implied crank HP, trap speed cross-check, and HP-per-liter smell test.
Dyno Math
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Gear Ratio & RPM Calculator
Find your engine RPM at any speed given your transmission gear, final drive ratio, and tire size.
Performance
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Turbo Boost Pressure Ratio
Convert boost PSI to pressure ratio, or work backwards from a target pressure ratio to required boost.
Forced Induction
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Fuel Injector Size Calculator
Size injectors for a target horsepower goal using BSFC, duty cycle, and number of cylinders.
Fuel System
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Horsepower โ†” Torque
Convert between horsepower and torque at any RPM using the SAE formula used on every dyno sheet.
Dyno Math
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Fuel Cost Calculator
Calculate cost per mile, monthly, and annual fuel spend. Compare premium vs regular for your car.
Daily Driver
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Compression Ratio Calculator
Calculate engine compression ratio from bore, stroke, head gasket thickness, deck clearance, and combustion chamber volume.
Engine Build
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AFR & Lambda Calculator
Convert between air-fuel ratio and lambda (ฮป) for gasoline, E85, ethanol, and diesel fuels.
Tuning
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Automotive Unit Converter
Nm โ†” lb-ft, kW โ†” HP โ†” PS, bar โ†” PSI, and every other conversion car people actually need.
Utility
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My Garage
Save your car's specs once and every calculator pre-fills with one click. Stored in your browser - no account.
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Guides

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BMW Chassis CodesE30 to G80, fully mapped
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BMW Engine CodesN54 vs N55 vs B58 vs S55
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Porsche Generations996 through 992 decoded
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About TunerBench

TunerBench is a collection of free precision calculators built for performance car enthusiasts, tuners, and builders. Every formula is sourced from SAE standards, factory service manuals, and established motorsport engineering references.

All calculations run entirely in your browser - no data is sent to any server, no account required. Even shared log reports travel inside the link itself, not through us. Use them on your phone in the garage or at your desk before a build.

Who These Tools Are For