Power to Weight Calculator

Power to weight ratio is the power you can produce on the bike, in watts, divided by your body weight in kilograms. The result, written W/kg, lets riders of different sizes compare like for like. This calculator does that division for a sprint, a 1-minute, a 5-minute or a threshold effort, and can add your bike to the weight.

What Power to Weight Ratio Measures

W/kg shows how much power you make for each kilogram you have to carry. A heavier rider may push more total watts, but a lighter rider with the same W/kg will climb at a similar speed. It says little about speed on flat roads, where air drag matters most. Car power-to-weight (horsepower per tonne) is a different measure and is not covered here.

The Formula

Rider W/kg = power (W) / body weight (kg)

System W/kg = power (W) / (body weight + bike weight) (kg)

Body weight in kg = weight in lb x 0.45359237

The four effort lengths used here (5 seconds, 1 minute, 5 minutes and functional threshold) come from Andrew Coggan's power profiling method¹.

How This Calculator Computes Your Result

Choose the effort length, then enter your best average power for that length in whole watts. FTP (functional threshold power) is the highest power you can hold for about an hour. If you do not know yours, the FTP Calculator can estimate it from a 20-minute, 8-minute or ramp test.

Enter your body weight in kg or lb. Pounds are converted with 1 lb = 0.45359237 kg. W/kg is shown to two decimals, with halves rounded up. If you add a bike and gear weight, you also get a system W/kg, which divides your power by the total mass of you and your bike. For FTP, you can choose men or women to see a rating and the watts you would need for each rating at your current weight.

What Your Result Means

The ratings below apply to FTP only. They are Garmin's FTP ratings, which Garmin says are based on research by Hunter Allen and Andrew Coggan in the book Training and Racing with a Power Meter². Treat them as coaching guidance, not a medical or racing standard.

For example, a 70 kg man with an FTP of 250 W is at 3.57 W/kg, which rates as Good. He would need 275 W to reach Excellent at the same weight.

Short efforts are not rated, because a 5-second or 1-minute W/kg is far higher than an FTP W/kg and must be compared only with the same effort length. For example, a 1,100 W sprint at 80 kg works out to 13.75 W/kg, far above any FTP value in the table.

Which Power Number to Enter

Each effort length tests a different part of your fitness. Coggan chose 5 seconds to reflect sprint (neuromuscular) power, 1 minute for anaerobic capacity, 5 minutes for VO2 max and the threshold effort for lactate threshold¹. Use your best recent power for the effort length you pick, from a power meter or smart trainer. Coggan's ranges were built for young adults and are applied the same way at any age¹, so older riders may want to compare mainly against their own past results.

Why W/kg Matters Most on Climbs

The power you need on a bike comes from gravity, rolling resistance and air drag. In the standard cycling power model, the gravity part grows in direct proportion to the combined mass of rider and bike, and on climbs that part dominates the total³. That is why W/kg, and system W/kg in particular, is the number that best tracks climbing speed.

A study of 24 professional road cyclists found that ability on climbs scaled with power divided by body mass, while ability on flat roads scaled with body mass raised to a much smaller power, about 0.32⁴. Put simply, extra weight costs little on the flat, but on climbs every kilogram counts. The climbers in that study made less total power than the flat-terrain riders (308 W against 356 W at the lactate threshold), but they were lighter⁴.

What Professional Cyclists Produce

In the same study, the professional riders produced about 5.4 to 5.7 W/kg at the onset of blood lactate accumulation, a lab marker close to threshold⁴. That is above the Superior line for men in the table above. A larger study of 144 male professionals found that sprinters had the highest W/kg for efforts of 5 to 30 seconds, while overall race contenders had the highest W/kg for efforts from 1 to 240 minutes⁵. Earlier work on elite riders showed that the best power across different effort lengths acts as "a signature" of each rider's strengths⁶. Comparing your own numbers across effort lengths can show whether you lean towards sprinting or climbing.