Support
Gear Ratio Calculator
Gear Ratio Calculator is being prepared for its first App Store release. The App Store link will be added here when available.
For help, bug reports, purchase questions, or privacy requests, email [email protected] with “Gear Ratio Calculator” in the subject. Include your device model, app version, the calculator mode, and steps to reproduce the issue. Share input values only if you want to.
To calculate a tooth ratio, enter driving teeth 20 and driven teeth 50, then tap Calculate. The reduction is 2.5000:1. For RPM, input 3000 RPM and ratio 2.5 produces 1200 RPM; the reverse direction returns 3000 RPM.
Use the outer tire diameter, not the wheel or rim size. Choose mm or inches and km/h or mph. Invalid or incomplete inputs must be corrected before calculating. Road speed is theoretical and assumes no tire slip.
Lifetime Pro is a one-time purchase with no subscription or trial. If access is not recognized, use Restore Purchases in Settings or the Pro sheet with the Apple Account used for purchase. Pending approvals do not unlock Pro until Apple verifies the transaction.
After a successful calculation, open the calculator’s menu and choose Favorite to save a named setup. Reopen or rename entries in Saved Setups. History keeps the latest 20 successful Pro calculations; delete an entry or use the trash button to clear it after confirmation.
Saved data stays in local app storage. There is no account or developer-operated backup or cloud sync. Restore Purchases restores eligible Pro access, not lost calculator data. Apple handles App Store billing and refund requests.