Cycling W/kg means watts per kilogram of rider body mass. The formula is:
W/kg = power in watts ÷ body mass in kilograms
A cyclist producing 260 watts at 75 kg has a ratio of 3.47 W/kg. That calculation is exact. What the result means is conditional.
W/kg is duration-specific. A five-second sprint at 15 W/kg, a five-minute effort at 5 W/kg and an FTP estimate at 3.5 W/kg describe different abilities. Write FTP W/kg, five-minute W/kg or 20-minute W/kg rather than presenting one unqualified number as a complete ranking.
Use the free cycling W/kg calculator for the arithmetic. Use this page for interpretation. If the question is specifically how FTP changes with age, use the maintained FTP and W/kg by age report. For bands based on training maturity, use the experience-level FTP benchmarks.
W/kg calculator: a worked example
Take a rider with an FTP estimate of 260 W and body mass of 75 kg:
- Keep the power anchor explicit: FTP = 260 W.
- Use body mass in kilograms: 75 kg.
- Divide 260 by 75: 3.4666....
- Report 3.47 W/kg at FTP.
If body mass is in pounds, divide pounds by 2.2046 first. A 165.3 lb rider is approximately 75 kg.
Two decimal places are useful for tracking the arithmetic. They do not make the FTP estimate, power meter or body-mass measurement equally precise. A small change should repeat under comparable conditions before it is treated as adaptation.
Cycling W/kg chart: translate the ratio back into watts
This chart shows the absolute FTP required for common ratios at three rider masses. It is a conversion chart, not a race-category or population-percentile ranking.
- 1.5 W/kg: 90 W at 60 kg; 113 W at 75 kg; 135 W at 90 kg.
- 2.0 W/kg: 120 W at 60 kg; 150 W at 75 kg; 180 W at 90 kg.
- 2.5 W/kg: 150 W at 60 kg; 188 W at 75 kg; 225 W at 90 kg.
- 3.0 W/kg: 180 W at 60 kg; 225 W at 75 kg; 270 W at 90 kg.
- 3.5 W/kg: 210 W at 60 kg; 263 W at 75 kg; 315 W at 90 kg.
- 4.0 W/kg: 240 W at 60 kg; 300 W at 75 kg; 360 W at 90 kg.
- 4.5 W/kg: 270 W at 60 kg; 338 W at 75 kg; 405 W at 90 kg.
- 5.0 W/kg: 300 W at 60 kg; 375 W at 75 kg; 450 W at 90 kg.
The chart exposes why W/kg and absolute watts answer different questions. At 4.0 W/kg, a 60 kg rider produces 240 W and a 90 kg rider produces 360 W. On a steep climb, the ratios are similar before bike mass and other forces are added. On a fast flat road, the additional absolute power may matter much more.
For an actual benchmark rather than a conversion, match the reference to the rider. The age-group FTP report explains the limits of age-qualified comparisons; the power-duration curve guide compares different effort lengths.
Why one W/kg number is not a power profile
Andrew Coggan's power-profile framework uses multiple durations—classically five seconds, one minute, five minutes and functional threshold—to expose different strengths. Coggan also warns that category-based values have limited practical use for deciding competitive ability: actual racing measures racing more directly.
That distinction matters because two cyclists can share the same FTP W/kg and be different athletes:
- one may have much higher five-minute power and be better on short climbs;
- one may have greater durability and hold a larger fraction of fresh power after three hours;
- one may sprint well while the other depends on sustained pace;
- one may be more aerodynamic or technically efficient; and
- one may have produced the FTP estimate with a different test or device.
Use the ratio to describe a defined effort. Use a complete power-duration curve, event demands and actual outcomes to describe the rider.
When W/kg predicts climbing—and when it does not
Gravity makes mass-normalised power useful uphill, but rider-only W/kg is not the complete climbing equation.
The system moving uphill includes rider, bicycle, clothing, bottles and equipment. A field hill-climb study by Jobson and colleagues found that mass-scaled physiological and power variables related strongly to performance, while also showing that aerodynamic resistance remained relevant on the 5.4% climb studied. More recent modelling by Horvath and Andersson found that the useful form of mass normalisation changes with course gradient, wind and other conditions.
In practice:
- Steeper, sustained climbing: rider and system W/kg become highly informative.
- Shallow climbs and rolling courses: aerodynamics, speed, momentum and absolute power retain more influence.
- Flat or fast riding: absolute power and aerodynamic drag usually deserve more attention than rider-only W/kg.
- Sprints and short accelerations: use duration-specific power; FTP W/kg does not predict the whole effort.
The power-to-speed calculator is better for modelling flatter riding. The VAM calculator adds climbing-specific context, and the aero-versus-weight guide explains when saving drag is more valuable than saving mass.
What is a good cycling W/kg?
There is no context-free threshold that turns a rider from recreational into competitive or from amateur into professional.
Widely shared W/kg tables can still orient a rider, but they need their methodology attached. Coggan's original framework was anchored at known high and low performances and cross-checked with available data; it was not built from a representative census of every cyclist. It also evaluates several durations, not FTP alone. Current Zwift grouping uses platform-specific metrics and Racing Score or power-profile inputs, so an old letter category should not be presented as a timeless physiological truth.
Ask five questions before interpreting a benchmark:
- Is this FTP, 20-minute, five-minute or another duration?
- How was the power measured and how was the anchor estimated?
- Which age, sex, training history and cycling population produced the reference?
- Is the goal climbing, time trialling, track racing, a sportive or general fitness?
- Does the table show a distribution, a coaching convention or a racing rule?
If a chart cannot answer those questions, treat its labels as rough orientation only.
How to improve W/kg without making the rider worse
The ratio has two mathematical inputs: watts and kilograms. That does not make the two training strategies equally useful or equally safe.
Build useful power
Increasing sustainable power improves W/kg without requiring body-mass reduction. The right training depends on the limiter and event, but the reliable foundations are consistent aerobic work, appropriately placed intensity, recovery and sufficient energy availability. Start with the FTP training knowledge hub, then calculate training ranges with the FTP zones tool.
Treat body mass as a health-led variable
The old version of this guide prescribed weight loss from generic body-fat cut-offs and promised a fixed W/kg gain in 12 weeks. Those claims have been removed. A ratio cannot determine whether someone should lose weight, and a coach's generic table is not a body-composition assessment.
The IOC consensus on Relative Energy Deficiency in Sport defines problematic low energy availability as an energy mismatch capable of impairing physiological and psychological function. The consequences can affect energy metabolism, reproductive function, bone and muscle health, immunity, glycogen synthesis, cardiovascular health and performance in both male and female athletes.
If an intentional body-mass change is appropriate, it should preserve training quality, recovery and health. Falling power, repeated illness, persistent fatigue, sleep disruption, menstrual disturbance, libido changes or recurrent injury should not be dismissed as the cost of a better ratio. The energy-availability calculator is an educational screen, not a diagnosis; persistent or concerning symptoms need appropriately qualified medical or sports-dietetic support.
How to compare W/kg over time
Use a repeatable measurement chain:
- the same power meter or trainer where practical;
- the same calibration and zero-offset routine;
- the same FTP or duration-specific test protocol;
- similar cooling, altitude and fatigue conditions;
- a consistent body-mass routine; and
- the date, device and protocol stored beside the result.
British Cycling's power guidance defines threshold power-to-weight as FTP divided by body mass and warns that overly aggressive weight loss can reduce power. It also treats power as one intensity tool used alongside the context of training zones—not as a standalone identity.
A 0.05 W/kg rise can be meaningful, noise or both. Repeatability matters more than the extra decimal place.
Which Roadman W/kg page should you use?
- Calculate my W/kg now: use the W/kg calculator.
- Understand W/kg and when it predicts speed: stay on this maintained guide.
- Compare FTP by age: use the age-group FTP benchmarks.
- Compare FTP by training experience: use the experience-level FTP benchmarks.
- Compare FTP, five-minute and sprint power: use the power-duration curve guide.
- Understand or test FTP: use the FTP training hub and FTP test guide.
- Review Alpe d'Huez estimates: use the Alpe d'Huez W/kg analysis.
These pages have separate jobs. The calculator owns arithmetic, this guide owns broad interpretation, and the benchmark reports own qualified comparisons.
Reviewed evidence and current references
- Creating Your Power Profile — Andrew Coggan, TrainingPeaks: source framework and explicit limitations of one-dimensional category judgements.
- Understanding Intensity: Power — British Cycling: official explanation of FTP power-to-weight and weight-loss caution.
- Allometric scaling of uphill cycling performance — Jobson et al., 2008: field evidence on mass scaling and hill-climb performance.
- Optimal body-mass normalisation over complex cycling courses — Horvath and Andersson, 2025: course-, wind- and gradient-dependent modelling.
- Power profiling and the power-duration relationship in cycling — Leo et al., 2022: review of duration-specific cycling power profiling.
- IOC consensus statement on REDs — Mountjoy et al., 2023: low-energy-availability definitions, health and performance consequences, and clinical boundaries.
The practical rule is simple: calculate the ratio accurately, label it honestly and improve the rider rather than chasing the label.