Free tool
Calculate W/kg for sprint, VO2, threshold, and endurance power.
Calculate cycling watts per kilogram across every duration that matters - 5-second sprint, 1-minute, 5-minute VO2max, FTP, and 60-minute endurance. Drop in your peak watts and body weight, get W/kg ratios for each duration plus Coggan-tier labels (Cat 5 up to World Class) for both male and female athletes. Free, no signup, runs in your browser.
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Power-to-weight ratios
| Duration | Watts | W/kg | Tier |
|---|---|---|---|
| Sprint (5 sec) | 1000 | 14.29 | Cat 4 |
| VO2max (5 min) | 350 | 5.00 | Cat 3 |
| Threshold (FTP) | 270 | 3.86 | Cat 3 |
| Endurance (60 min) | 230 | 3.29 | Cat 3 |
How it works
- 1
Enter your weight
Kilograms or pounds, naked-and-bathroom - pick one convention and stay with it.
- 2
Drop in your peak watts
Any combination of sprint, VO2, threshold, and endurance power. Empty fields are skipped.
- 3
See the ratios
Each duration converts to a W/kg figure and a Coggan tier label, instantly.
- 4
Identify your shape
High sprint W/kg with weak endurance = power rider. Strong threshold, weak sprint = climber. Use the ratios to pick races that suit you.
The math
There is no calibration coefficient, no conversion factor, no exponent. Power divided by mass, period. The complexity is in choosing the right power duration to divide.
Worked example: 70 kg rider with 270 W FTP
Threshold W/kg = 270 ÷ 70 = 3.857 W/kg. That places this rider in Cat 4 territory on the Coggan tables - a solid recreational racer.
Worked example: same rider drops to 67 kg
FTP unchanged at 270 W: 270 ÷ 67 = 4.03 W/kg. A 3 kg drop pushed the rider from Cat 4 to Cat 3 on climbing-specific metrics without any change in absolute fitness. This is why bike racers obsess about body composition.
The Coggan tables - duration-specific tiers
Andy Coggan published a power-profile chart that maps four durations (5 sec, 5 min, 60 min FTP, 60 min sub-threshold) to ability categories. Sprint W/kg above 22 marks world-class fast-twitch; threshold above 5.7 marks elite endurance. Most amateurs have unbalanced profiles - one strong duration and one or two weaker ones - and matching events to your profile beats trying to be flat across the board.
Why pounds throw off the math
Watts per pound is not a standard metric. Convert weight to kilograms first (lb × 0.453592) so your ratio is comparable to published tables and team data.
How to use this in training
- Pick the right metric for your event. Crit racers care about sprint and VO2 W/kg. Time trialists care about threshold W/kg over a flat course. Mountain racers care about threshold W/kg over an hour. Gran fondo riders care about endurance W/kg over four-plus hours.
- Move the lever that's actually weak. Most amateurs reflexively try to add watts. If your weight has crept up 4 kg, you can gain more W/kg by losing 3 kg than by training for the same period.
- Don't over-optimize at the cost of health. Cutting too far harms power, recovery, immune function, and bone density. Sustainable endurance fueling beats race-week weight loss every time.
- Track the trend, not the daily number. Weight fluctuates 1-2 kg day to day from glycogen, hydration, and digestive contents. A 7-day rolling average is the honest signal.
- Use ratios in race selection. If your endurance W/kg is elite but your sprint is recreational, don't enter races that finish in bunch sprints.
Common mistakes & misconceptions
Weighing in kit and comparing to naked-weight figures
Add 1.5-3 kg for shoes, helmet, kit, and bottles. The Coggan tables assume naked body weight. Mixing conventions inflates your apparent tier.
Comparing outdoor sprint power to indoor sustained power
Outdoor peak sprints will often be higher than trainer sprints (more rolling momentum, better leverage). Sustained power is usually lower outdoors. Apples to apples, not durations to settings.
Treating W/kg as a single score
There is no one W/kg. Your sprint, VO2, threshold, and endurance ratios are independent. World-class climbers have modest sprint W/kg; world-class sprinters have modest threshold W/kg.
Using uncalibrated power meters
A 3% calibration drift moves a 4.0 W/kg rider to 4.12 W/kg without any real change. Zero-offset your power meter before every important effort.
Cutting weight from the wrong side
Losing 3 kg of muscle to chase climbing W/kg may also drop your FTP, leaving the ratio unchanged or worse. Body-composition changes - lower fat, similar muscle - beat raw weight loss.
Quoting one-time peak numbers
A single great test is data. A number you can repeatably hit is your fitness. Use averages of your best three efforts over the last 60 days, not a one-shot record.
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Open the toolkitFAQ
What is power-to-weight ratio?
Power-to-weight ratio is your sustained power output in watts divided by your body weight in kilograms. It is the single most predictive metric for climbing performance and a key input for any race that involves vertical gain.
Why is W/kg more important on climbs?
On flat ground, raw power overcomes wind resistance, and a heavier rider with more absolute watts can win sprints and time trials. On climbs, gravity dominates aerodynamic drag, and the ratio of watts to body mass determines vertical speed.
How do I measure my 5-second sprint power?
Perform a maximal seated or standing acceleration on flat ground after a thorough warm-up. Most head units automatically capture and store your 5-second peak. Take the best from several attempts on the same day.
What is a good threshold W/kg for a competitive amateur?
Cat 3 racers in North America typically sit between 3.7 and 4.3 W/kg at FTP. Cat 2 starts around 4.3, Cat 1 around 4.8, and elite domestic-level pros above 5.5. Numbers vary by federation and reference.
Should I weigh myself with kit or without?
For consistent tracking, weigh yourself naked in the morning after using the bathroom. For race-day weight, include kit, shoes, helmet, and full bottles. The numbers will differ by 1.5-3 kg.
How is endurance W/kg different from FTP W/kg?
FTP is one-hour sustainable power. Endurance W/kg uses your average power over a 60-minute steady ride at low intensity - typically 65-75% of FTP. The endurance ratio reflects what you can sustain for hours, not minutes.
Do the Coggan tier labels apply to women?
The original Coggan tables included separate scaling for women, reflecting differences in lean muscle mass at the population level. Our labels follow the male reference; women should subtract roughly 0.5-0.7 W/kg from each tier band as an approximation.
Why does my outdoor W/kg differ from my trainer W/kg?
Outdoor power tends to be 5-10% lower than calibrated trainer power for the same effort. Wind, terrain variability, traffic, and effort pacing all suppress sustained outdoor output. Use trainer numbers for training math; expect a drop outside.
Save your training to a real log
A calculator gives you a number. A training log gives you a trajectory. Domestique tracks W/kg by duration so the trend is unmistakable.
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