Wind Turbine Capacity Factor Calculator
Calculate wind turbine capacity factor from rated power and annual energy.
Compare your turbine output to onshore and offshore industry averages.
Wind Turbine Capacity Factor (CF)
Capacity factor measures actual energy generated as a fraction of theoretical maximum if the turbine ran at rated power 24/7/365.
The formula: CF = Annual energy / (Rated power × 8,760 hours)
Where 8,760 = total hours in a year.
A 2 MW turbine producing 5,000 MWh/year: CF = 5,000 / (2 × 8,760) = 5,000 / 17,520 = 28.5%
Typical capacity factors (2026):
| Type | Capacity Factor |
|---|---|
| Onshore wind, poor site | 18-25% |
| Onshore wind, average US | 30-37% |
| Onshore wind, excellent site | 40-50% |
| Offshore wind, average | 40-50% |
| Offshore wind, excellent (North Sea) | 50-60% |
| Floating offshore (deep water) | 55-65% |
| Small wind (residential) | 8-15% (often disappointing) |
Comparison to other generation:
| Source | Typical CF |
|---|---|
| Nuclear | 90-95% (baseload) |
| Coal | 50-60% (cycling) |
| Natural gas combined cycle | 55-70% |
| Solar PV | 18-26% |
| Hydroelectric | 35-50% |
| Geothermal | 70-90% |
| Onshore wind average | 35% |
| Offshore wind average | 45% |
Why CF varies so much:
- Wind speed at site — power scales with cube of wind speed
- Hub height — taller = better wind, +30-50% CF
- Turbulence — lowers efficiency
- Curtailment — grid can’t always absorb output (downtime)
- Maintenance — typically 2-5% downtime
- Wake effects — turbines downwind of others lose 5-15% CF
- Seasonal patterns — winter often 50% higher than summer
The “rated power” trap: Rated power is at 12-15 m/s wind. In reality, wind blows below rated speed most of the time:
- Below cut-in (3-4 m/s): 0% output
- Cut-in to rated (4-12 m/s): rises with cube of wind
- Rated to cut-out (12-25 m/s): full rated power
- Above cut-out (25+ m/s): shut down for safety
Recent industry trends: Modern turbines have bigger rotors per kW of generator to capture more wind at low speeds. This increases CF without raising rated power. Examples:
- Old: 2 MW with 80m rotor (CF ~30%)
- New: 2 MW with 130m rotor (CF ~45%) — more area, more swept volume
This is why onshore CF averages have risen from ~28% (2010) to ~37% (2024) without major rated-power increases.
For homeowners: Small wind systems (under 20 kW) typically achieve CF of 8-15%. Below 25% you’re often paying more for electricity than the utility charges. Solar usually outcompetes residential wind unless:
- Site has consistent 10+ mph winds
- Tall tower (60+ ft above obstacles) installed
- Local utility has time-of-use rates favoring wind
Calculating your own AEP: AEP (kWh) = Rated power (kW) × 8,760 × CF × Availability
Where availability = 95-98% for well-maintained turbines.
For a 5 kW residential turbine at CF 12%: AEP = 5 × 8,760 × 0.12 × 0.97 = 5,099 kWh/year
At $0.15/kWh utility rate, that’s $765/year of electricity offset — modest payback for a $20,000-40,000 system.