Power-to-weight explained
Power-to-weight is your power output divided by your body mass, in watts per kilogram (W/kg). It is the single number that best predicts how fast you climb — but it says less on the flat, and it changes completely depending on whether you mean a five-second sprint or an hour-long effort. Here is what W/kg is, why it matters, and where it misleads.
Open the Power-to-Weight calculatorWant your number now? The Power-to-Weight calculator divides the power you enter by your body mass and shows the W/kg for whatever duration you are testing.
What power-to-weight (W/kg) is
Power-to-weight is a ratio: the power your legs produce divided by how much body you have to carry. Cyclists express it in watts per kilogram because it lets riders of very different sizes be compared on a like-for-like basis. A 60 kg rider holding 240 W and a 90 kg rider holding 360 W both sit at 4 W/kg — and up a steep climb they would go at roughly the same speed, even though the heavier rider is producing 50% more raw power.
- Power
- your power output in watts, measured at a stated duration (for example 5 s, 1 min, 5 min or FTP)
- Body mass
- your body weight in kilograms; some riders use total system mass including bike and kit for climbing estimates
- W/kg
- the resulting ratio; only comparable when the two riders use the same duration and the same mass definition
The formula is trivial; the care is all in what you feed it. A W/kg figure is meaningless without knowing the duration behind the watts and whether the mass is body-only or the whole loaded bike.
Why it matters most on climbs
On a climb, most of your power goes into lifting mass against gravity, and the resisting force scales directly with total weight. Because both the useful power and the resistance scale with the rider, dividing one by the other — W/kg — predicts climbing speed well. That is why grand-tour climbers tend to be light: a higher ratio wins when the road tilts up.
On the flat it is a different story. There, the dominant force is aerodynamic drag, which depends on frontal area and speed, not on body mass. Two riders at the same raw watts will go at nearly the same flat speed regardless of weight, so raw watts and aero position matter more than the ratio. This is the same physics our cycling speed from power tool models: change the gradient and the balance between gravity and drag shifts, which is why W/kg is decisive on a 10% wall and almost irrelevant in a flat time trial.
FTP W/kg vs sprint W/kg — duration changes everything
There is no single W/kg number for a rider. Power falls as duration rises, so your ratio does too. A trackie might hit 18 W/kg for five seconds yet sit near 4 W/kg for an hour; a time-trial specialist may reverse that ranking. When someone quotes a W/kg figure, the first question is always: over how long?
The most commonly cited number is FTP W/kg — your functional threshold power (roughly the highest power you can hold for about an hour) divided by mass. It best describes sustained climbing and steady efforts. A 5-second W/kg describes your sprint and is a completely different, much larger figure. Comparing your FTP ratio against someone’s sprint ratio, or vice versa, tells you nothing useful.
Approximate FTP W/kg tiers
The table below gives a rough sense of where FTP W/kg figures tend to fall. Treat these as broad orientation only, not a test result.
| Broad level | Approx. FTP W/kg |
|---|---|
| Recreational | ~2 W/kg |
| Trained | ~3 W/kg |
| Competitive club | ~4 W/kg |
| Elite / professional | 5+ W/kg |
These bands are approximate. Men’s and women’s figures differ, the boundaries are fuzzy, and where you land depends heavily on the testing protocol — a ramp test, a 20-minute test scaled by 95%, and a true one-hour effort can all give different numbers for the same rider. The tiers above are our summary of the power-profiling approach popularised by Allen & Coggan; we deliberately do not reproduce their full copyrighted profiling chart, which is far more granular. For a proper picture, test yourself and use a detailed profiling table from the source.
What is a good power-to-weight ratio?
“Good” is relative to your goal and to the duration you mean. For sustained climbing, many riders would call an FTP figure around 3 W/kg a solid trained level and 4 W/kg competitive — but that is a claim with caveats: it assumes a genuine one-hour-ish FTP, it differs between men and women, and it says nothing about whether that ratio wins the races you actually enter. A better benchmark than any table is your own trend: is your W/kg at a given duration rising over a season? If so, you are getting faster where it counts, whatever tier a chart assigns you.
What W/kg does not tell you
A single W/kg number ignores nearly everything that decides a real ride: aerodynamics and position on the flat, bike handling and descending skill, pacing and tactics, the terrain of your events, and how repeatable your efforts are. Two riders at the same W/kg can finish minutes apart. Just as important, chasing the ratio by losing weight can backfire — cut too far and power drops, recovery suffers, and health can be harmed, sometimes lowering the very ratio you were trying to raise. This is general information for orientation, not coaching or medical advice; consult a qualified professional before making nutrition or training changes.
Frequently asked questions
What is a good power-to-weight ratio for cycling?
It depends on duration and rider. As a rough guide for FTP (roughly one-hour) power, many recreational riders sit near 2 W/kg, trained club riders near 3, competitive club riders near 4, and elite riders reach 5 W/kg or more. These figures are approximate, differ between men and women, and depend on the testing protocol.
Is power-to-weight or raw watts more important?
It depends on the terrain. On steep climbs, where gravity dominates, W/kg is the better predictor. On the flat, where aerodynamic drag dominates, raw watts and your aero position matter more than the ratio.
Should I lose weight to improve my W/kg?
Not necessarily. W/kg can rise either by raising power or lowering mass, but cutting weight can reduce power, harm health, and hurt performance if taken too far. This is general information, not coaching or medical advice.
Related tools and reading
Power-to-Weight calculator
Enter your power and body mass to get your W/kg for any duration you test.
ToolFTP Training Zones calculator
Turn your FTP into training zones so the watts behind your W/kg have context.
Sources
- Hunter Allen & Andrew Coggan, Training and Racing with a Power Meter (VeloPress) — power profiling and W/kg by duration. Checked 24 Aug 2026.
- Andrew Coggan, Power Profiling — overview of the W/kg-by-duration framework. Checked 24 Aug 2026.