W/kg
Watts Per Kilogram
Watts per kilogram (W/kg) is the power-to-weight ratio that measures cycling power output relative to body weight. Learn what W/kg means and how it affects climbing and racing performance.
Quick Answer
W/kg — Watts per kilogram (W/kg) is your power-to-weight ratio—your cycling power output divided by your body weight. It's the key metric for climbing and overall cycling performance, making it easier to compare cyclists of different sizes.
What Does W/kg Mean?
W/kg stands for watts per kilogram. It measures how much power you produce relative to how much you weigh.
This matters because cycling—especially climbing—requires moving your body weight. A heavier cyclist needs more absolute power to climb at the same speed as a lighter cyclist.
W/kg Formula:
W/kg = Power (watts) ÷ Body weight (kg)
Example: A cyclist with 280W FTP weighing 70kg:
W/kg = 280 ÷ 70 = 4.0 W/kg
Use our Watts Per Kilo Calculator to find your power-to-weight ratio.
Why W/kg Matters
| Scenario | What Matters Most |
|---|---|
| Climbing | W/kg is everything—gravity doesn't care about absolute watts |
| Flat roads | Absolute watts matter more (aerodynamics dominate) |
| Time trials | Mix of watts and aerodynamics |
| Racing | W/kg for hills, absolute watts for attacks on flat |
On a 7% gradient, W/kg determines your speed. On flat ground at 40km/h, absolute power matters more.
W/kg Benchmarks by Level
| W/kg (FTP) | Category | Description |
|---|---|---|
| 1.5-2.5 | Untrained | New to cycling |
| 2.5-3.0 | Recreational | Regular rider |
| 3.0-3.5 | Enthusiast | Dedicated amateur |
| 3.5-4.0 | Competitive | Club racer |
| 4.0-4.5 | Strong amateur | Regional competitor |
| 4.5-5.0 | Elite amateur | National level |
| 5.0-5.5 | Domestic pro | Lower professional |
| 5.5-6.0 | WorldTour pro | Top professionals |
| 6.0+ | Grand Tour winners | Elite of elite |
For detailed charts, see FTP Chart by Watts Per Kg and Watts Per Kg by Age.
W/kg by Gender
Due to physiological differences, female cyclists typically have lower absolute W/kg values at the same competitive level:
| Level | Male W/kg | Female W/kg |
|---|---|---|
| Recreational | 2.5-3.0 | 2.0-2.5 |
| Competitive | 3.5-4.0 | 3.0-3.5 |
| Elite amateur | 4.5-5.0 | 4.0-4.5 |
| Professional | 5.5-6.5 | 5.0-5.8 |
See Good FTP for Women and Good FTP for Men for more details.
Improving Your W/kg
You can improve W/kg by:
- Increasing power – Most sustainable approach
- Reducing weight – Has limits and risks
- Both – Optimal but challenging
Power vs Weight Trade-offs
| Approach | Pros | Cons |
|---|---|---|
| Increase FTP | Builds fitness, more sustainable | Takes time |
| Lose weight | Quick W/kg gains | Can lose power, health risks |
| Both | Best results | Requires careful balance |
Generally, focus on building power first. Weight loss beyond optimal racing weight often decreases power more than the weight benefit.
W/kg for Climbing Speed
Your W/kg directly predicts climbing speed on sustained gradients:
| W/kg | ~Speed on 8% Climb |
|---|---|
| 3.0 | ~11 km/h |
| 3.5 | ~13 km/h |
| 4.0 | ~15 km/h |
| 4.5 | ~17 km/h |
| 5.0 | ~19 km/h |
| 5.5 | ~21 km/h |
Approximate speeds assuming standard road bike and no drafting
Short-Duration W/kg
W/kg varies by duration. Most cyclists produce higher W/kg for shorter efforts:
| Duration | Typical Ratio to FTP |
|---|---|
| 5 seconds | 200-300% |
| 1 minute | 130-150% |
| 5 minutes | 110-120% |
| 20 minutes | 105% |
| 60 minutes (FTP) | 100% |
Your VO2 Max power (4-8 minutes) determines your ability to respond to attacks, while FTP determines sustained climbing ability.
Common Questions
What W/kg do I need to race competitively?
For local amateur races, 3.5-4.0 W/kg is typically competitive. Cat 1/2 racing requires 4.0-4.5 W/kg. See What is a Good FTP? for detailed benchmarks.
Should I lose weight to improve W/kg?
Only if you're above your optimal racing weight. Losing weight below this point often decreases power disproportionately. Most amateur cyclists benefit more from training to increase power than from weight loss.
How much can W/kg improve?
Untrained cyclists might improve from 2.0 to 3.5+ W/kg over several years. Trained cyclists typically improve 5-10% per year. Genetic ceiling varies significantly between individuals.
Is 5 W/kg good?
Yes—5.0 W/kg for FTP puts you at elite amateur or domestic professional level. Only a small percentage of cyclists ever reach this level, and it typically requires years of dedicated training plus favorable genetics.