How many watts do I need to ride at 20 mph?

20 mph (≈32 km/h) requires approximately 200–230 W for a typical 80 kg rider. Aerodynamic drag is the dominant force at this speed, so riding position matters a great deal.

Does body weight matter on flat roads?

On flat roads, weight has a relatively small effect on required power. Heavier riders experience slightly more rolling resistance and a larger frontal area, but aerodynamics (CdA) dominates above ~25 km/h.

What is CdA in cycling?

CdA is the product of Drag Coefficient (Cd) and Frontal Area (A) in m². It's the single most important parameter in cycling aerodynamics. Lower CdA means faster riding for the same power. Typical road bike values range from 0.25 m² (aggressive aero) to 0.45 m² (upright).

What is rolling resistance (Crr)?

Crr is a coefficient quantifying energy loss through tyre deformation. Road tyres on smooth tarmac are typically 0.004–0.006. Good race tyres can be as low as 0.002.

Does headwind affect required cycling power?

Enormously. A 5 m/s headwind can double the power required at 30 km/h because aerodynamic drag scales with the cube of air speed. Use the Advanced Settings in the calculator to simulate headwind.

How accurate is this cycling power calculator?

The calculator uses the widely-accepted Martin et al. (1998) steady-state power model and estimates CdA from body measurements within ~10% accuracy. For precise power targets, use a calibrated power meter.

Why does the calculator show rider power at the pedals and not wheel power?

Rider power (produced at the pedals) is higher than wheel power due to drivetrain losses. A typical drivetrain is ~97% efficient. The calculator shows the power your legs actually need to produce.

Cycling Power Calculator

Q: How many watts does it take to ride at 30 km/h?

For an average 80 kg rider on a road bike in the hoods position, roughly 200–250 W is needed on flat roads with no wind. Exact values depend on aerodynamic profile, tyre rolling resistance, and drivetrain efficiency.

Estimate cycling watts from your speed, weight, and height.How many watts does it take to ride at 30 km/h? What about 20 mph? Enter your weight and height to get fast, physics-based cycling power estimates across a full speed range.

An average 80 kg rider needs roughly 220–240 watts to ride 30 km/h on flat roads.

Flat road · Steady state · No gradient · Estimates only

Rider Inputs

Rider Weight

Rider Height

Units

How many watts to ride 30 km/h?

You’ll need approximately

205W

A rider weighing 80 kg at 180 cm typically needs ~205 W to hold 30.0 km/h on flat ground.

Target Speed: 30 km/h

15 km/h45 km/h

20 km/h30 km/h40 km/h

Detailed Speed Breakdown

Common speeds for quick comparison

Speed	Power	Effort
20 km/h	75W	Easy
25 km/h	125W	Moderate
30 km/hBenchmarkClosest	205W	Tempo
35 km/h	305W	Threshold
40 km/h	445W	Very Hard
45 km/h	615W	Very Hard

Frequently Asked Questions

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All figures are physics-based estimates for flat road, steady-state riding with no gradient. Real-world power requirements will vary due to wind, road surface, rider technique, and other factors. This tool is for indicative purposes only — not a substitute for a calibrated power meter.

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