Eighth Mile Calculator
Convert eighth-mile ET and MPH to quarter-mile equivalents.
Many tracks are eighth-mile, but quarter-mile times are the universal benchmark. This calculator converts your 1/8-mile ET and trap speed into estimated quarter-mile figures using established conversion factors.
1/8 to 1/4 Mile Conversion
These multipliers work well for most street and strip cars. Very high-powered or traction-limited cars deviate slightly, since the second half of the quarter mile depends on power and aero more than the launch.
How to Use This Calculator
- Enter your eighth-mile ET in seconds.
- Optionally enter eighth-mile trap MPH.
- Read the quarter-mile estimates.
Worked Example
Frequently Asked Questions
Multiply the eighth-mile ET by about 1.557. For example, an 8.5-second eighth-mile is roughly a 13.2-second quarter-mile.
Multiply the eighth-mile trap speed by about 1.25. So 85 MPH at the eighth becomes roughly 106 MPH at the quarter.
Eighth-mile tracks need less land and are safer for street cars and bracket racing, so they're very common, especially in some regions.
They're good estimates for typical cars, usually within a few tenths and a few MPH. High-power or low-traction cars can deviate more.
Yes — convert to quarter-mile figures first, then use the trap-speed or ET horsepower calculators.