1/4 Mile Calculator
Estimate quarter-mile and 1/8-mile ET and trap speed from horsepower and weight, or work backwards from a time slip to horsepower.
Press Calculate to print your slip
Estimate only. Real passes vary with traction, weather, gearing and the driver.
Want 0-60 too? Try the 0-60 Calculator
On this page
Four tools in one
Pick what you want to find. Go forward from horsepower and weight to an ET and trap speed, go backwards from a real time slip to the power it takes to run it, or convert between the 1/8 mile and the quarter mile. New to drag racing? Here is how long a quarter mile is (1,320 ft) and what each distance on the strip means.
What you need
- Race weight
- The vehicle's weight plus the driver. Enter both and the calculator adds them.
- Power, ET or trap speed
- Whichever you know: a horsepower figure, or the numbers from a time slip.
- Layout
- Drivetrain and gearbox, which change how well the car launches.
What you get
- Quarter-mile ET and trap speed
- 1/8 mile ET and speed
- Estimated crank and wheel horsepower from a time slip
- A performance class, printed on a time slip you can compare run to run
ET vs trap speed: what each tells you
Elapsed time (ET) is how long the run takes from the starting line to the finish line. Trap speed is how fast the vehicle is going as it crosses the finish. They answer different questions.
ET shows the whole run
It depends on the launch, the first 60 feet, every shift and the power. A great launch can take tenths off without any extra horsepower.
Trap speed shows the power
By the finish the launch matters much less, so trap speed tracks power-to-weight closely. That's why working out horsepower from trap speed is usually more reliable than from ET.
The formulas behind the estimate
The calculator uses the formulas drag racer and engineer Patrick Hale published in the 1980s. They predict a run from power-to-weight ratio alone, and they work in reverse to turn a time slip into a horsepower figure.
Quarter-mile ET
ET = 5.825 × (W ÷ P)1/3
Trap speed
mph = 234 × (P ÷ W)1/3
Power from ET
P = W × (5.825 ÷ ET)3
Power from trap speed
P = W × (mph ÷ 234)3
- W, race weight
- Pounds, vehicle plus driver.
- P, power
- Crank horsepower. Wheel horsepower is converted first: RWD 15% loss, FWD 12%, AWD 20%, motorcycles and EVs 10%.
- Launch adjustment
- ET is scaled by drivetrain and gearbox (FWD and CVT a little slower, AWD and dual-clutch a little quicker), the same model the 0-60 calculator uses.
- 1/8 mile
- 1/8 mile ET is about 64% of the quarter-mile ET (1/4 ≈ 1/8 × 1.56), and 1/8 mile speed about 80% of the trap speed.
Worked example: 3,200 lb with the driver and 400 hp is 8.00 lb/hp. The cube root of 8 is 2, so ET = 5.825 × 2 = 11.65 s and trap speed = 234 ÷ 2 = 117.0 mph.
What changes your real ET
The 60-foot time
The launch is where most runs are won or lost. A better 60-foot time carries through to every mark after it.
Weather and altitude
Hot, humid or high-altitude air holds less oxygen, so engines make less power. Racers track this as density altitude.
Tires and track prep
Street tires spin where drag radials or slicks grip, and a prepped track surface adds grip too.
Gearing and shifts
Each shift costs time. Gearing that crosses the finish near the top of a gear, not just after a shift, helps.
Weight
Every pound matters. Fuel load, passengers and spare parts in the trunk all count toward race weight.
The driver
Launch rpm, clean shifts and staying in the throttle make a real difference, especially with a manual gearbox.
How to use it
Pick what to find
ET from power, power from ET, power from trap speed, or a 1/8 to 1/4 mile conversion.
Enter the weights
Vehicle weight and driver weight. Switch units if your numbers are in kilograms.
Add power or a slip
Type horsepower, or the ET or trap speed from a real run, and say which distance it's from.
Print and compare
Press Calculate. Change one input at a time to see what a power upgrade or weight loss would do.
Reading a real time slip
After a pass, the track hands you a slip with the numbers below. Here's what each line means and how it connects to this calculator.
- R/T, reaction timeFrom the green light to the moment the car leaves the starting beam. It isn't part of the ET.
- 60 ftTime to cover the first 60 feet. The clearest measure of launch quality.
- 330 ftAn early split that shows how the car pulls through first gear and the first shift.
- 1/8 mile ET and MPHTime and speed at 660 feet. Many local strips finish here.
- 1,000 ftA late split, mostly used on shorter tracks and for tuning.
- 1/4 mile ET and MPHTime and trap speed at 1,320 feet. Use these in Power from ET or Power from speed.
Example estimates
Race weight includes a 170 lb driver. These are calculator estimates for example builds, not road-test results.
| Example build | 1/4 mile ET | Trap speed | 1/8 mile ET |
|---|---|---|---|
| Compact sedan158 hp, 2,900 lb, FWD, CVT | 16.37 s | 87.0 mph | 10.48 s |
| Hot hatch241 hp, 3,150 lb, FWD, dual-clutch | 14.00 s | 97.6 mph | 8.96 s |
| Sports coupe300 hp, 3,300 lb, RWD, manual | 13.17 s | 103.5 mph | 8.43 s |
| V8 muscle car480 hp, 3,850 lb, RWD, manual | 11.83 s | 115.2 mph | 7.57 s |
| Supercharged V8797 hp, 4,250 lb, RWD, automatic | 10.43 s | 132.2 mph | 6.68 s |
| Superbike200 hp, 440 lb bike | 9.71 s | 153.3 mph | 6.22 s |
Our estimates vs real time slips
We ran six recently tested cars through the calculator with their rated horsepower and published test weight (plus a 180 lb driver), then compared the result with the magazine’s time slip.
| Car (as tested) | hp | Weight (lb) | Our ET @ mph | Tested ET @ mph |
|---|---|---|---|---|
| Toyota GR86 (2022, manual)Car and Driver | 228 | 2,838 | 13.78 s @ 98.9 | 14.0 s |
| Mazda MX-5 Miata RF Club (2024)Edmunds | 181 | 2,437 | 14.19 s @ 96.1 | 14.8 s @ 92.9 |
| Volkswagen Golf R (2025, DCT)Edmunds | 328 | 3,376 | 12.29 s @ 105.7 | 12.8 s @ 107.8 |
| Toyota GR Corolla (2025, automatic)Edmunds | 300 | 3,345 | 13.02 s @ 102.9 | 14.1 s @ 100.4 |
| Tesla Model 3 Performance (2024)Road & Track | 510 | 4,050 | 10.93 s @ 115.6 | 11.0 s @ 125 |
| Chevrolet Corvette Stingray Z51 (2027)Edmunds | 535 | 3,693 | 11.04 s @ 121.0 | 11.4 s @ 120.2 |
What the comparison shows. The ET estimate was quicker than the real slip for all six cars, by 0.07 seconds for the Model 3 Performance up to 1.08 seconds for the automatic GR Corolla, with a typical gap of about 0.4 seconds. Read our ET as what a clean, well-launched run could do. Trap speed tracks power more closely: the estimate landed within about 3 mph for four of the five cars with a published trap speed. The exception is again the Tesla, whose electric motors keep pulling harder at speed than the formula assumes.
Racing on an eighth-mile track? Use the 1/8 ↔ 1/4 mile tab at the top of this page for a quick conversion, or the 1/8 to 1/4 mile calculator for factors by car type, a full conversion chart and your own ratio from a slip. For what makes a time quick, see quarter-mile times explained.
Sources and method
ET and trap speed come from Patrick Hale's power-to-weight formulas, run forwards for an estimate or backwards from a time slip. The drivetrain and gearbox launch adjustments are our own, checked against real time slips.
- Our estimates compared with published time slips
- NIST Special Publication 811: unit conversion factors
Updated September 2026. Built and checked by the 0-60calc Team. Found a mistake? Tell us and we will check it against the source.
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Questions racers ask
What is a good quarter-mile time?
For a stock street car, anything under 14 seconds feels quick, under 12 seconds is fast, and under 10 seconds is race-car territory or a heavily modified street machine.
How accurate is a quarter mile calculator?
The Hale formula gives a sound first estimate for a well-launched run on a prepped track. Real ETs vary with traction, weather, gearing and the driver, so treat the result as a target, not a guarantee.
Should I enter crank or wheel horsepower?
The formula works with crank (flywheel) horsepower. If your number comes from a chassis dyno, choose Wheel (WHP) and your drivetrain, and the calculator adds a typical drivetrain loss back first.
How do I convert a 1/8 mile time to a quarter mile?
Multiply the 1/8 mile ET by about 1.56 and the 1/8 mile speed by about 1.25. The 1/8 ↔ 1/4 mile mode does this for you in either direction, and the 1/8 to 1/4 mile calculator adds factors for different cars and a full chart.
Why is my trap speed good but my ET slow?
Trap speed mostly reflects power, while ET also depends on the launch. A strong trap speed with a slow ET usually points to wheelspin or a weak 60-foot time.
What weight should I enter?
Race weight: the vehicle as it runs, with fuel, plus the driver. Enter the vehicle weight and your own weight and the calculator adds them together.