How accurate is the quarter mile calculator?

The calculator uses common drag racing estimation formulas that assume good traction, an efficient launch, and average gearing. It is useful for comparison and planning, but real track times can differ due to driver skill, surface, weather, and vehicle setup.

Can I use metric units like kW and kg?

Yes. You can switch between horsepower and kilowatts, and between pounds and kilograms. The calculator converts internally and shows results in both imperial and metric units where relevant.

What is a good quarter mile time for a street car?

Modern everyday cars often run 15–17 seconds. Hot hatches and performance sedans are commonly in the 12–14 second range. Dedicated drag cars and high-end supercars can run well under 11 seconds, with top-tier builds deep into the 8s and quicker.

Why do my real track times differ from the estimate?

Real-world quarter mile times depend heavily on traction, launch technique, shift speed, gearing, aerodynamics, weather, and track prep. The formulas assume ideal conditions and average efficiency, so they are best used for ballpark estimates and comparing setups rather than exact predictions.

Quarter Mile Calculator (Drag Racing)

Estimate 1/4 mile elapsed time (ET), trap speed, and horsepower from vehicle weight and power – or reverse it from a known quarter mile time.

Vehicle weight (with driver)

Race weight including driver, fuel, and any ballast.

Engine power

Use wheel horsepower for real-world ET estimates.

Drivetrain loss (optional)

If you only know crank hp, enter % loss (e.g. 15% for RWD).

Traction / launch factor

Higher factor = slower ET to reflect traction limits.

Run comparison

Save multiple setups or passes to compare weight, power, ET and trap speed.

#	Weight (lb)	Power (hp)	ET (s)	Trap (mph)	Notes
No runs saved yet. Calculate a setup, then click “Add current estimate”.

What is a quarter mile in drag racing?

In drag racing, the quarter mile (1/4 mile) is a straight-line distance of exactly 1,320 feet, or 402.34 meters. Two vehicles start from a standing start and race to the finish line.

The two key results from a quarter mile pass are:

Elapsed time (ET) – how many seconds it takes to cover the 1/4 mile.
Trap speed – the vehicle’s speed at the finish line, usually measured over the last 66 ft.

Formulas used in this quarter mile calculator

The calculator uses widely accepted drag racing estimation formulas. They are empirical (based on real-world data), so they are approximations, not exact physics models.

1. ET from weight and horsepower

Base formula (imperial):

\[ \text{ET (s)} \approx 5.825 \times \left(\frac{W}{HP}\right)^{1/3} \]

\(W\) = race weight in pounds (car + driver + fuel)
\(HP\) = wheel horsepower

We then multiply by a traction factor to account for real-world launches:

\[ \text{ET}_\text{adjusted} = \text{ET} \times F_\text{traction} \]

2. Trap speed from weight and horsepower

Base formula (imperial):

\[ V_\text{trap} \text{ (mph)} \approx 234 \times \left(\frac{HP}{W}\right)^{1/3} \]

3. Horsepower from ET and weight

Rearranging the ET formula gives an estimate of wheel horsepower:

\[ HP \approx W \div \left(\frac{\text{ET}}{5.825}\right)^3 \]

How to get realistic quarter mile estimates

Use accurate race weight. Weigh the car with driver and typical fuel load, or estimate carefully.
Use wheel horsepower if possible. Dyno results at the wheels are more realistic than crank ratings.
Adjust for drivetrain loss. If you only know crank hp, enter a drivetrain loss percentage.
Pick a traction factor that matches your setup. Slicks on a prepped track will run much quicker than street tires on a dusty road.

Typical quarter mile times by vehicle type

Vehicle type	Approx. ET (1/4 mile)	Notes
Everyday family car	15–17 s	Normal street tires, modest power
Hot hatch / performance sedan	12–14 s	Modern turbo engines, good traction control
High-end sports car / supercar	10–11 s	Launch control, sticky tires
Street-legal drag build	8–10 s	Slicks, suspension and gearing optimized for the strip
Dedicated drag car	< 8 s	Roll cage, chute, race fuel, very high power

Limitations and assumptions

These formulas are great for ballpark estimates and comparing setups, but they cannot perfectly predict your time. Real-world results depend on:

Driver reaction and launch technique
Tire compound, pressure, and track prep
Gearing, shift points, and transmission type
Altitude, temperature, and air density
Aerodynamics and drivetrain efficiency

Always treat the output as an estimate, not a guarantee. The best way to know your quarter mile time is still to run the car at a proper drag strip.