Gear Ratio & Speed Calculator

Drivetrain & Setup Simulator

Only for iPhone

Free · Designed for iPhone. Not verified for macOS.

iPhone

Simulate drivetrain changes with What If? Compare tires, final drive, and transmission swaps on cruising RPM and speed across all gears. Gear Ratio & Speed Calculator is an all-in-one drivetrain calculator and setup simulator designed for track enthusiasts, racers, off-road builders, and gearheads. Calculate exact relationships between engine RPM, vehicle speed, gear ratios, final drive, and tire sizes. Plan modifications and preview their impact before turning a single wrench. WHAT IF? VEHICLE SETUP SIMULATOR • Compare your current vehicle setup with a new What If? configuration side by side. • Evaluate changes in tire dimensions, final drive ratios, and transmission swaps. • Compare cruising RPM at 60, 80, 100, 120, and 130 km/h (or mph). • Check top speed and speed at specific RPM intervals (3,000 to redline). • Detailed gear-by-gear ratio and speed delta comparison. • Visual gear graph comparing current vs new setup curves. • Dedicated impact breakdown cards for tire size, final drive, and transmission changes. • Experiment freely without modifying your saved Garage vehicle profile. RPM & SPEED • RPM to Speed: Calculate true vehicle speed from engine RPM, selected gear, final drive, and tire dimensions. • Speed to RPM: Find required engine RPM for any target highway cruising speed. GEAR RATIO & FINAL DRIVE • Calculate overall drive ratio for each transmission gear. • Ring & pinion final drive swap analysis and ratio changes. GEAR SPEED • Full-spectrum speed table across all gears from 1,000 RPM up to engine redline. • Easily find shift points and maximum speed in each gear. TIRE SIZE & TIRE COMPARISON • Supports Metric tire sizes (e.g. 215/40R18, 265/70R17.5) and Flotation Inch sizes (e.g. 35x12.50R17). • Full decimal wheel diameter support including 17.5-inch wheels. • Side-by-side tire comparison: diameter, circumference, sidewall height, and speedometer error percentage. SHIFT RPM • Analyze engine RPM drop after upshifting from each gear. • Review step ratio percentages and gear spacing to keep engine in the powerband. TRANSMISSION PRESETS • Explore 74 transmission presets from manufacturers and performance applications. • Covers popular manual, automatic, and dual-clutch transmissions (TREMEC, ZF, Ford, GM, Toyota, Honda, Hyundai, BMW, Porsche, and more). • Quick 1-tap setup with realistic factory gear ratios. GARAGE • Save and manage multiple vehicle profiles with custom tire specs, final drives, and gear ratios. • Load any saved vehicle directly into the What If? simulator or individual calculators. SPROCKET / TOOTH COUNT • Motorcycle and chain-drive ratio calculator for front and rear sprockets. • Calculate sprocket tooth changes and target gearing. OFFLINE & UNIT SUPPORT • Instant calculations with zero latency — works completely offline without network connection. • Seamless 1-tap toggle between Metric (km/h, mm) and Imperial (mph, inches).

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• New What If? Vehicle Setup Simulator: simulate tire, final drive, and transmission swaps side by side • Compare cruising RPM, speed at RPM, and gear-by-gear performance • Added full access to all 74 transmission presets • Improved 17.5-inch decimal wheel diameter support

Version 1.1.3

The developer, HyeongSeok Oh, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .

  • Data Used to Track You

    The following data may be used to track you across apps and websites owned by other companies:

    • Identifiers

  • Data Not Linked to You

    The following data may be collected but it is not linked to your identity:

    • Identifiers

Privacy practices may vary, for example, based on the features you use or your age. Learn More

Accessibility

The developer has not yet indicated which accessibility features this app supports. Learn More

Information

Seller
HyeongSeok Oh
Size
6.7 MB
Category
Utilities
Compatibility
Requires iOS 16.0 or later.
  • iPhone
    Requires iOS 16.0 or later.
  • Mac
    Requires macOS 13.0 or later and a Mac with Apple M1 chip or later.
  • Apple Vision
    Requires visionOS 1.0 or later.
Languages
English and 5 more
  • English, German, Japanese, Korean, Portuguese, Spanish
Age Rating
4+
Copyright
© 2026 DomiLabs
  • Developer Website
  • Privacy Policy

    • More by HyeongSeok Oh

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