About Regear Calculator
A free, open-source utility built for automotive enthusiasts, off-roaders, and truck owners to take the guesswork out of drivetrain modifications.
Site Purpose
Upgrading to larger tires or modifying your vehicle's suspension fundamentally changes its mechanical leverage. This often results in sluggish acceleration, poor fuel economy, and increased transmission wear. Regear Calculator was created to provide accurate, mathematical recommendations for restoring factory performance through differential regearing. We believe these tools should be free, accessible, and easy to understand for everyone from weekend warriors to professional mechanics.
Author Information
Developed by SquidForged, owners are long time Wrangler owners, automotive tinkerers, and gear heads who wanted to provide free tools to support the 4x4 modding community in a consolidated and trustworthy location (not to replace forums or other reputable online resources but rather add to a toolset without having to do hours of deep dive research all over the interwebs). If you like the work we're doing here, please use and share the site (or consider sponsoring our ongoing work).
Support Development
If you find Regear Calculator valuable, consider supporting SquidForge's ongoing development with a monthly donation.
Editorial Standards
We are strictly committed to accuracy, transparency, and engineering best practices. All calculations provided on this site are based on verified mathematical formulas used in the automotive industry.
- Data Sources: Our recommendations are derived from standard gear ratio and tire diameter formulas used throughout the automotive aftermarket industry.
- Transparency: Our formulas are public. We don't hide the math behind a paywall.
- Professional Verification: We always recommend consulting with an ASE-certified drivetrain specialist before purchasing parts.
Methodology
Our core calculator uses the standard automotive engineering formula to determine the effective gear ratio change when altering tire size:
We then cross-reference this mathematical ideal against commercially available aftermarket ring and pinion sets (e.g., 4.10, 4.56, 4.88) to provide actionable recommendations based on your specific driving style—whether that's highway cruising, heavy towing, or rock crawling.