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1/8 ↔ 1/4 Mile Converter Calculator
Convert eighth-mile times to quarter-mile estimates
The 1/8 to 1/4 mile converter translates elapsed times and trap speeds between eighth-mile and quarter-mile racing using standard factors.
Formula: 1/4 ET ≈ 1/8 ET × 1.56 · 1/4 MPH ≈ 1/8 MPH × 1.27
What this number means
This converts an eighth-mile ET and MPH to an estimated quarter-mile ET and MPH, and back, using typical sportsman-car relationships. Conversions are approximations — cars strong in the back half beat the factor, cars that lay over miss it.
What to change next
Use the converted number as a starting dial when you switch distances, then replace it with real time-trial data before eliminations. A car that consistently beats or misses its conversion is telling you where its power is made.
Worked example
An eighth-mile pass of 7.20 at 96 MPH converts to ≈ 11.23 at ≈ 122 MPH in the quarter.