Wheel Backspace Calculator
Get precise wheel fitment measurements instantly with our wheel backspace calculator. This tool converts between backspace and offset measurements, ensuring your wheels fit perfectly every time.
How the Calculator Works
The backspace calculator performs instant conversions between two critical wheel measurements. Input your wheel width along with either your current backspace measurement or desired offset, and receive accurate conversions in both metric and imperial units.
This offset to backspace calculator eliminates manual calculations and reduces fitment errors. Whether you’re working with manufacturer specifications that list offset or you’ve measured backspace directly, the calculator provides both values for complete fitment clarity.
Backspace to offset calculators prove invaluable when comparing wheels. Get both backspace and offset values instantly to make informed purchasing decisions.
Understanding Your Results
Here’s a crucial point about wheel manufacturing: most manufacturers use standardized offsets rather than custom measurements. If you measure 4.65 inches of backspacing on a 12-inch wide wheel and the offset and backspacing calculator shows -47mm offset, the actual manufactured wheel likely features -44mm offset due to industry standardization.
Off-road and truck wheels are built with specific, uniform offsets designed for particular vehicle applications. For example, the popular 17×9 wheel configuration typically uses a -12mm offset across most manufacturers. This standardization ensures proper fitment and performance while maintaining an aggressive stance.
The use of this offset to backspacing conversion tool is a good starting point, but keep in mind that final wheel selection should account for these manufacturing standards. The calculator provides precise mathematical conversions, while real-world wheel options align with established fitment specifications.
Ready to nail your wheel fitment? Use the calculator below to convert between backspace and offset measurements for your next wheel upgrade.
Important: Most manufacturers use standardized offsets. Your calculated result may differ from the actual manufactured wheel offset due to industry standards. For example, a 17x9 wheel typically uses -12mm offset across most manufacturers.
| Width (in) | -44mm | -25mm | -18mm | -12mm | -6mm | 0mm | 6mm | 12mm | 18mm | 25mm | 38mm | 44mm | 50mm |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 5.0 | 1.268 | 2.016 | 2.291 | 2.528 | 2.764 | 3.000 | 3.236 | 3.472 | 3.709 | 3.984 | 4.496 | 4.732 | 4.969 |
| 5.5 | 1.518 | 2.266 | 2.541 | 2.778 | 3.014 | 3.250 | 3.486 | 3.722 | 3.959 | 4.234 | 4.746 | 4.982 | 5.219 |
| 6.0 | 1.768 | 2.516 | 2.791 | 3.028 | 3.264 | 3.500 | 3.736 | 3.972 | 4.209 | 4.484 | 4.996 | 5.232 | 5.469 |
| 6.5 | 2.018 | 2.766 | 3.041 | 3.278 | 3.514 | 3.750 | 3.986 | 4.222 | 4.459 | 4.734 | 5.246 | 5.482 | 5.719 |
| 7.0 | 2.268 | 3.016 | 3.291 | 3.528 | 3.764 | 4.000 | 4.236 | 4.472 | 4.709 | 4.984 | 5.496 | 5.732 | 5.969 |
| 7.5 | 2.518 | 3.266 | 3.541 | 3.778 | 4.014 | 4.250 | 4.486 | 4.722 | 4.959 | 5.234 | 5.746 | 5.982 | 6.219 |
| 8.0 | 2.768 | 3.516 | 3.791 | 4.028 | 4.264 | 4.500 | 4.736 | 4.972 | 5.209 | 5.484 | 5.996 | 6.232 | 6.469 |
| 8.5 | 3.018 | 3.766 | 4.041 | 4.278 | 4.514 | 4.750 | 4.986 | 5.222 | 5.459 | 5.734 | 6.246 | 6.482 | 6.719 |
| 9.0 | 3.268 | 4.016 | 4.291 | 4.528 | 4.764 | 5.000 | 5.236 | 5.472 | 5.709 | 5.984 | 6.496 | 6.732 | 6.969 |
| 9.5 | 3.518 | 4.266 | 4.541 | 4.778 | 5.014 | 5.250 | 5.486 | 5.722 | 5.959 | 6.234 | 6.746 | 6.982 | 7.219 |
| 10.0 | 3.768 | 4.516 | 4.791 | 5.028 | 5.264 | 5.500 | 5.736 | 5.972 | 6.209 | 6.484 | 6.996 | 7.232 | 7.469 |
| 10.5 | 4.018 | 4.766 | 5.041 | 5.278 | 5.514 | 5.750 | 5.986 | 6.222 | 6.459 | 6.734 | 7.246 | 7.482 | 7.719 |
| 11.0 | 4.268 | 5.016 | 5.291 | 5.528 | 5.764 | 6.000 | 6.236 | 6.472 | 6.709 | 6.984 | 7.496 | 7.732 | 7.969 |
| 11.5 | 4.518 | 5.266 | 5.541 | 5.778 | 6.014 | 6.250 | 6.486 | 6.722 | 6.959 | 7.234 | 7.746 | 7.982 | 8.219 |
| 12.0 | 4.768 | 5.516 | 5.791 | 6.028 | 6.264 | 6.500 | 6.736 | 6.972 | 7.209 | 7.484 | 7.996 | 8.232 | 8.469 |
| 12.5 | 5.018 | 5.766 | 6.041 | 6.278 | 6.514 | 6.750 | 6.986 | 7.222 | 7.459 | 7.734 | 8.246 | 8.482 | 8.719 |
| 13.0 | 5.268 | 6.016 | 6.291 | 6.528 | 6.764 | 7.000 | 7.236 | 7.472 | 7.709 | 7.984 | 8.496 | 8.732 | 8.969 |
| 13.5 | 5.518 | 6.266 | 6.541 | 6.778 | 7.014 | 7.250 | 7.486 | 7.722 | 7.959 | 8.234 | 8.746 | 8.982 | 9.219 |
| 14.0 | 5.768 | 6.516 | 6.791 | 7.028 | 7.264 | 7.500 | 7.736 | 7.972 | 8.209 | 8.484 | 8.996 | 9.232 | 9.469 |
| 14.5 | 6.018 | 6.766 | 7.041 | 7.278 | 7.514 | 7.750 | 7.986 | 8.222 | 8.459 | 8.734 | 9.246 | 9.482 | 9.719 |
| 15.0 | 6.268 | 7.016 | 7.291 | 7.528 | 7.764 | 8.000 | 8.236 | 8.472 | 8.709 | 8.984 | 9.496 | 9.732 | 9.969 |
| 15.5 | 6.518 | 7.266 | 7.541 | 7.778 | 8.014 | 8.250 | 8.486 | 8.722 | 8.959 | 9.234 | 9.746 | 9.982 | 10.219 |
| 16.0 | 6.768 | 7.516 | 7.791 | 8.028 | 8.264 | 8.500 | 8.736 | 8.972 | 9.209 | 9.484 | 9.996 | 10.232 | 10.469 |
Backspace = ((Wheel Width + 1) ÷ 2) + Offset (in inches)
Important: This chart shows calculated backspace values in inches using the industry-standard formula. Most manufacturers use standardized offsets rather than custom measurements. Your actual wheel selection should account for these manufacturing standards. For example, a 17x9 wheel typically uses -12mm offset across most manufacturers.