Weight & pace impact calculator.
See exactly how a change in body weight reshapes running pace, cycling W/kg and race times — adjusted for gradient because hills magnify the effect.
Frequently asked
How does body weight affect running pace?
On flat ground, ~1% body weight lost ≈ ~1% faster pace. On moderate hills the effect doubles, and on steep climbs it can triple.
How does weight matter on the bike?
Climbs are dictated by W/kg. On flats aerodynamics dominate and weight matters far less. Steep grades over 10% magnify the impact dramatically.
What is W/kg?
Watts per kilogram of body weight: FTP ÷ weight in kg. Pros >6.0, competitive age-group 3-4, recreational 2-3.
Will losing 10 lb make me much faster?
For a 160 lb runner, ~6% lighter ≈ 6% faster on flat ground (~30 sec/mi at 8:00 pace). On a hilly marathon that can mean 20-30 min faster.
Is leaner always faster?
No. Dropping weight too fast reduces power and hurts recovery. Optimal race weight is individual — aim for the lightest weight you can hit your power targets at.
Weight isn't the lever. Training is.
Body composition shifts come from consistent, smart training. 1:1 coaching builds the block that delivers both.
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