Cycling Drafting Energy Savings Calculator
See how much power you save sitting in a draft versus riding solo at the same speed, and the effective watts you keep in your legs.
How it works
Solo P = (Crr·m·g + ½·ρ·CdA·v²)·v · Draft P = (Crr·m·g + ½·ρ·CdA·v²·(1 − reduction))·v
Air drag rises with the square of speed, so at racing pace most of a rider's power fights the wind. Sitting behind another rider lets you ride in their turbulent wake, cutting the aerodynamic term by a quarter to a half depending on how close and how sheltered you are. Rolling resistance and any climbing force are unchanged, which is why drafting helps most on fast flat roads and barely at all on a steep climb.
Worked example
At 40 km/h (11.1 m/s) and 82 kg, solo power is about 337 W, of which roughly 293 W is air drag. A 30% draft removes 88 W of that drag term, dropping your power to about 249 W — a saving near 26%.
Frequently asked questions
How much does drafting actually save?
Wind-tunnel and field studies put the second rider's saving at roughly 25–35%, rising above 40% deep inside a large bunch and toward 50% in a full team time-trial line. The closer the wheel and the bigger the rider in front, the greater the shelter.
Why does drafting barely help when climbing?
On a steep climb speeds are low, so air drag is a small share of total power and the gravity term dominates. With little wind resistance to hide from, the draft removes only a few watts — which is why climbs shatter groups that stayed together on the flat.
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This calculator is for educational purposes. Double-check important results before acting on them.