Drag Racing & HP
1/4-Mile ET & Trap Speed Estimator
Calculate theoretical elapsed times (ET), trap speeds, and 0–60 MPH based on vehicle weight and dyno horsepower.
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How to Use This Tool
- Enter wheel or flywheel horsepower from your dyno sheet.
- Enter total race weight including driver, fuel, and passengers.
- Select drivetrain type for a small correction factor.
- Read estimated 1/4-mile ET, trap speed, and 0–60 MPH.
- Compare estimates against verified time slips in Racer Hub.
The Formula & Physics Behind the Math
These calculators use empirical drag racing approximations: ET ≈ 6.29 × (weight ÷ HP)^(1/3) with a drivetrain correction, and trap speed ≈ 224 × (HP ÷ weight)^(1/3). 0–60 is derived as max(1.8, ET × 0.42 − 0.5). Real-world ET depends on traction, launch technique, weather, density altitude, and power delivery — treat results as a planning baseline, not a guaranteed slip.
Frequently Asked Questions
Should I use wheel horsepower or crank horsepower?
Use the number that matches your weight basis. Dyno WHP is most accurate for trap-speed math. Add ~15% if converting from crank estimates on RWD cars.
Why is my real ET slower than the estimate?
Street tires, soft suspension, altitude, heat, and poor launches add time. Forced-induction spool delay and traction limits are not modeled here.
Does weight include the driver?
Yes — use race weight: curb weight + driver + fuel + cargo. Drag racers often add 170–200 lbs for the driver alone.
Can I use this as an 1/8-mile ET calculator?
The primary output is 1/4-mile ET and trap speed. As a rough rule of thumb, many cars run about 0.65× their quarter-mile ET in the eighth — verify with a real slip when it matters.
Is this better than a dyno sheet?
No — a dyno measures power. This tool estimates how that power might translate to ET if traction and weather cooperate. Use both: dyno for tuning, this calculator for goal-setting.