Horsepower Calculator
Estimate horsepower from a drag-race style pass.
You can solve from elapsed time or trap speed, then convert the result to watts and kilowatts.
Result
--
Run the calculation to see the horsepower estimate.
| Metric | Value |
|---|---|
| Horsepower | -- |
| Kilowatts | -- |
| Watts | -- |
| Input method | -- |
Quick Answer
Use vehicle weight with either elapsed time or trap speed to estimate horsepower, then convert the result to watts and kilowatts.
How to Calculate
- Choose the drag-race method.
- Enter the vehicle weight and the matching speed value.
- Choose weight and speed units if needed.
- Click Calculate.
Formula
Elapsed time method: HP = weight / (elapsed / 5.825)^3
Trap speed method: HP = weight x (speed / 234)^3
Watts = horsepower x 745.7
Worked Examples
Example 1: 3,400 lb and 13.2 seconds gives about 324 horsepower.
Example 2: 3,400 lb and 105 mph gives about 311 horsepower.
Example 3: 300 horsepower is about 223,710 watts.
How to Interpret Your Results
| Output | Meaning | Action |
|---|---|---|
| Horsepower | Estimated engine or wheel power. | Compare it with dyno results or manufacturer claims. |
| Kilowatts | Metric power equivalent. | Use it for international specs. |
| Watts | Electrical-style power equivalent. | Use it when comparing with other power units. |
Frequently Asked Questions
The formula estimates power from the vehicle's performance, so it is often used as a wheel horsepower estimate.
Yes. The calculator converts kilograms and kilometers per hour before using the formula.
Trap speed gives another estimate of power and is often compared with elapsed time.
Related Calculators
References
- OmniCalculator reference page
- 1 horsepower equals 745.7 watts.
- Last reviewed: March 2026.