Quarter Mile Calculator: Estimate Your ET & Trap Speed
Free quarter mile calculator using proven formulas. Estimate your 1/4 mile ET and trap speed from horsepower and weight. Then verify with real GPS timing.
How to Use the Calculator
- Enter your vehicle's weight in pounds (include fuel, driver, and modifications)
- Enter your vehicle's horsepower (SAE, wheel HP, or estimated dyno HP)
- The calculator instantly shows your estimated quarter mile ET and trap speed
- Your result falls into a performance bracket (sub-10s, 10-11s, 11-12s, etc.)
The Formula: Brock Yates / Roger Huntington
This calculator uses the industry-standard Brock Yates quarter mile prediction formula, used by performance engineers and drag racers for decades. The formulas are:
- ET = 5.825 × (Weight ÷ HP)^(1/3) — Estimates quarter mile elapsed time
- Trap Speed = 234.24 × (HP ÷ Weight)^(1/3) — Estimates terminal velocity at the finish line
These formulas were developed by analyzing thousands of drag racing results and remain surprisingly accurate for initial estimates.
Accuracy and Limitations
The Brock Yates formula typically estimates within ±0.3 to ±0.5 seconds for street cars with good traction. However, real-world results depend heavily on factors the calculator cannot measure:
- Traction and grip — A car with poor traction will be much slower than the formula predicts
- Launch technique — Bad launches cost 0.3–0.5 seconds. The formula assumes perfect execution
- Weather — Hot days and high altitude can add 0.3–0.7 seconds versus optimal conditions
- Gearing — Poorly matched gears lose power off-the-line or waste potential top-end speed
- Transmission efficiency — Slipping automatics vs. well-shifted manuals, CVTs, and dual-clutch boxes perform differently
- Road surface — A grippy drag strip surface vs. asphalt vs. concrete makes a huge difference
Performance Brackets: What is a Good Quarter Mile Time?
| Bracket | Range | Typical Examples |
|---|---|---|
| Sub 10s | Under 10.0 seconds | Twin-turbo, supercharger, high-boost, 400+ hp |
| 10–11s | 10.0–10.99 seconds | Turbo 4-cyl, naturally-aspirated V8, 300+ hp |
| 11–12s | 11.0–11.99 seconds | Turbo 4-cyl, V6, light modifications, 250+ hp |
| 12–13s | 12.0–12.99 seconds | Stock 300+ hp cars, tuned 4-cyl, 200+ hp |
| 13–14s | 13.0–13.99 seconds | Stock sport cars, 250–300 hp |
| 14s+ | 14.0 seconds and above | Stock standard sedan, economy cars |
Why GPS Timing Beats Any Calculator
A calculator gives you a starting point, but real GPS timing shows you actual results. FastTrack uses GPS Doppler-derived speed combined with 100Hz accelerometer launch detection to measure 0-60 and quarter mile times with accuracy within ±0.05–0.1 seconds.
When you use the calculator and then verify with real GPS data, you learn exactly how your car performs in your conditions. You can then use mod-aware leaderboards to see which upgrades actually produce the fastest times for your platform.