Power to Weight Ratio Calculator
Watts per kg for cyclists (FTP), hp/ton & kW/tonne for cars, hp/lb for aircraft — with a unit converter and a reverse solver. 100% client-side, no data leaves your device.
Power-to-weight calculator
Reverse solver
Pick a target ratio, then solve for the power you need (given your mass) or the mass you must hit (given your power).
Presets & benchmark tables
Tap a preset to load it into the Calculator tab. Figures are approximate manufacturer claims (curb weight, rated power) — fine for comparison, not for spec sheets.
Cars (hp per metric ton)
Aircraft (hp per lb)
Cycling FTP categories (W/kg)
| W/kg (FTP) | Category | Typical rider |
|---|---|---|
| < 2.0 | Untrained | New to structured riding |
| 2.0 – 3.0 | Recreational | Regular weekend rider |
| 3.0 – 4.0 | Trained | Club rider, trains consistently |
| 4.0 – 5.0 | Competitive | Licensed racer, strong amateur |
| 5.0+ | Elite | Pro continental and WorldTour level |
Car classes by hp per metric ton
| hp/ton | Class | Example |
|---|---|---|
| < 100 | Economy | City cars, small MPVs |
| 100 – 150 | Average | Family sedans |
| 150 – 250 | Sporty | Hot hatches, sport sedans |
| 250 – 400 | Performance | Sports cars |
| 400+ | Supercar | Exotics, hypercars |
Reference
Formula
Power-to-weight ratio = P ÷ m, where P is power and m is mass. In SI units the result is W/kg. The same physical quantity can be expressed in any power unit per any mass unit:
- Cycling: W/kg (FTP ÷ rider mass, ideally rider + bike)
- Automotive: hp per metric ton or kW per tonne
- Aviation: hp per lb (power loading; jets use thrust-to-weight instead)
Exact unit factors used here
| Conversion | Factor |
|---|---|
| 1 hp (mechanical) | 745.7 W |
| 1 PS (metric horsepower) | 735.5 W |
| 1 kW | 1000 W |
| 1 lb | 0.45359237 kg |
| 1 metric ton | 1000 kg |
| 1 short ton (US) | 907.18474 kg |
Why it matters
Power-to-weight predicts acceleration and climbing far better than power alone: doubling the mass halves the acceleration for the same force. But it does not predict top speed on flat ground (aerodynamic drag dominates there) or cornering, braking, or efficiency.
Scope boundary
This tool computes the static power-to-weight ratio only — one number from power ÷ mass. It does not:
- Estimate 0–60 mph times or quarter-mile ETs — see the horsepower calculator for acceleration modelling.
- Assess aerobic fitness or training zones — see the VO2 max calculator for that.
- Model aerodynamic drag, rolling resistance, drivetrain losses, or gearing — all of which decide real-world speed alongside this ratio.
If you need drivetrain-loss or boost-adjusted horsepower figures, start at the horsepower calculator, then bring the result here.
Frequently asked questions
Free tool by NRTechStudio