This watts per kilo calculator is a powerful tool used to measure an athlete’s power output relative to their body weight, a critical metric cycling and other endurance sports.
For example, imagine two cyclists:
- Cyclist A: 75 kg, generating 300 watts
- Cyclist B: 60 kg, generating 270 watts
At first glance, Cyclist A seems more powerful. However, when we calculate watts per kilo:
- Cyclist A: 300 W / 75 kg = 4 W/kg
- Cyclist B: 270 W / 60 kg = 4.5 W/kg
We see that Cyclist B actually has a higher power-to-weight ratio, potentially giving them an advantage, especially on climbs.
Watts Per Kilo Calculator
| Athlete | Weight (kg) | Power (W) | Duration | W/kg | Performance Level |
|---|---|---|---|---|---|
| Cyclist A | 75 | 300 | 1 hour | 4.0 | Very Good |
| Runner A | 60 | 240 | 30 min | 4.0 | Very Good |
| Rower A | 85 | 425 | 20 min | 5.0 | Excellent |
| Cyclist B | 70 | 350 | 20 min | 5.0 | Excellent |
| Runner B | 55 | 192.5 | 1 hour | 3.5 | Good |
| Cyclist C | 68 | 306 | 1 hour | 4.5 | Very Good |
| Cyclist D | 80 | 400 | 1 hour | 5.0 | Excellent |
| Runner C | 72 | 280 | 45 min | 3.9 | Good |
| Rower B | 90 | 450 | 15 min | 5.0 | Excellent |
| Cyclist E | 65 | 290 | 30 min | 4.5 | Very Good |
| Cyclist F | 78 | 360 | 1 hour | 4.6 | Very Good |
| Runner D | 62 | 250 | 30 min | 4.0 | Very Good |
| Rower C | 82 | 410 | 20 min | 5.0 | Excellent |
| Cyclist G | 77 | 370 | 1 hour | 4.8 | Very Good |
| Runner E | 58 | 220 | 45 min | 3.8 | Good |
| Cyclist H | 74 | 330 | 1 hour | 4.5 | Very Good |
Watts per Kilogram Chart
| Category | Untrained | Fair | Good | Very Good | Excellent | Exceptional |
|---|---|---|---|---|---|---|
| W/kg | < 2.0 | 2.0-2.9 | 3.0-3.9 | 4.0-4.9 | 5.0-5.9 | > 6.0 |
| Cyclists | ||||||
| Male (Amateur) | < 2.5 | 2.5-3.5 | 3.5-4.5 | 4.5-5.5 | 5.5-6.5 | > 6.5 |
| Female (Amateur) | < 2.0 | 2.0-3.0 | 3.0-4.0 | 4.0-5.0 | 5.0-6.0 | > 6.0 |
| Male (Elite) | < 4.0 | 4.0-5.0 | 5.0-6.0 | 6.0-7.0 | 7.0-8.0 | > 8.0 |
| Female (Elite) | < 3.5 | 3.5-4.5 | 4.5-5.5 | 5.5-6.5 | 6.5-7.5 | > 7.5 |
| Runners | ||||||
| Male (Amateur) | < 2.8 | 2.8-3.8 | 3.8-4.8 | 4.8-5.8 | 5.8-6.8 | > 6.8 |
| Female (Amateur) | < 2.3 | 2.3-3.3 | 3.3-4.3 | 4.3-5.3 | 5.3-6.3 | > 6.3 |
| Male (Elite) | < 4.1 | 4.1-5.1 | 5.1-6.1 | 6.1-7.1 | 7.1-8.1 | > 8.1 |
| Female (Elite) | < 3.6 | 3.6-4.6 | 4.6-5.6 | 5.6-6.6 | 6.6-7.6 | > 7.6 |
| Rowers | ||||||
| Male (Amateur) | < 3 | 3–4 | 4–5 | > 5 | ||
| Female (Amateur) | < 2 | 2–3 | 3–4 | > 4 | ||
| Male (Elite) | < 4–5 | > 5–7 | >7–9 | >9–11 | >11–13 | >13 |
| Female (Elite) | < 3–4 | >4–6 | >6–8 | >8–10 | >10–12 > | >12 |
Watts Per Kilo Formula
The Watts Per Kilo Formula is:
Watts per Kilo = Power Output (Watts) / Body Weight (Kilograms)Power Output: Measured in watts, this is the rate at which energy is expended.
Body Weight: Measured in kilograms, this normalizes the power output across different body sizes.
If an athlete weighing 70 kg generates 280 watts:
280 W / 70 kg = 4 W/kgHow to Calculate Watts per Kilo?
To calculate watts per kilo, follow these steps:
- Measure power output: Use a power meter or ergometer to determine the watts generated during an effort.
- Weigh yourself: Ensure accurate body weight in kilograms.
- Divide power by weight: Use the formula mentioned earlier.
A 65 kg cyclist sustains 260 watts during a 20-minute time trial.
260 W / 65 kg ≈ 4 W/kgThis result indicates a “Very Good” performance level according to our chart.
What is the W per Kilo?
Watts Per Kilo, often abbreviated as W/kg, is a crucial performance metric used primarily in endurance sports, especially cycling. It represents the power output of an athlete relative to their body weight.
This measurement is calculated by dividing an athlete’s power production (measured in watts) by their body mass (measured in kilograms). The resulting figure provides a standardized way to compare the performance capabilities of athletes with different body sizes and weights.
Watts Per Kilo is particularly important in activities where an athlete must overcome gravitational forces, such as cycling uphill or running. A higher W/kg ratio generally indicates a better power-to-weight ratio, which can translate to improved performance in these scenarios.
Is 3.6 Watts per Kilo Good?
In cycling, for a one-hour effort:
- For amateur cyclists, 3.6 W/kg is indeed good.
- For professional cyclists, it would be considered moderate, as they often sustain 5-6 W/kg for similar durations.
A 70 kg amateur cyclist maintaining 252 watts for an hour:
252 W / 70 kg = 3.6 W/kgThis performance would place them in the “Good” category, showing significant training and fitness.
What is a Good Watts per Kg?
For a trained amateur cyclist in a one-hour effort:
- 3-4 W/kg is considered good
- 4-5 W/kg is very good
- >5 W/kg is excellent
A “good” watts per kg value varies based on several factors:
Duration of effort: Shorter efforts allow higher W/kg.
Training level: Professional athletes achieve higher values than amateurs.
Age and gender: These can affect power output capabilities.
A 68 kg cyclist sustaining 306 watts for an hour:
306 W / 68 kg = 4.5 W/kgThis would be considered a “very good performance” for an amateur.
Sources / References
- Training Peaks: Understanding Cycling Power Metrics
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