Wave Height Energy Calculator
Calculate ocean wave energy (wave power) from significant wave height and wave period using the standard deep-water wave power formula. Wave power is expressed in kilowatts per metre (kW/m) of wave crest. This is the fundamental metric used by NOAA and the US Department of Energy's wave energy resource assessments. Enter the significant wave height and peak wave period to calculate wave power density.
Wave power formula (deep water)
P = (ρ × g2 × Hs2 × T) / (64 × π)
Where: P = wave power per metre of crest (W/m), rho = seawater density = 1,025 kg/m3, g = 9.81 m/s2, Hs = significant wave height (m), T = wave period (s). This formula applies to deep water (depth greater than L/2, where L is wavelength).
A simplified approximation used in resource assessments is P (kW/m) = 0.5 * Hs2 * T, which gives nearly the same result.
Wave height energy calculator: frequently asked questions
How is wave energy calculated from wave height?
The wave power formula per unit crest width is: P = (rho * g^2 * Hs^2 * T) / (64 * pi), where rho is seawater density (1025 kg/m3), g is gravitational acceleration (9.81 m/s2), Hs is significant wave height in metres, and T is wave period in seconds. This gives power in watts per metre of wave crest.
What is significant wave height?
Significant wave height (Hs) is defined as the average height of the highest one-third of waves in a sea state. It is the standard measure used by NOAA and meteorological services in wave forecasts and reports. It approximates what a trained observer would estimate as the average wave height.
What are typical ocean wave energy values?
Open ocean swell in productive wave energy regions typically carries 20 to 70 kW per metre of wave crest. The US West Coast averages 20 to 40 kW/m. Portugal and the UK's Atlantic coasts can exceed 60 kW/m. Wave energy resources are mapped by NOAA and the US Department of Energy.
What is wave period and why does it matter?
Wave period is the time in seconds for successive wave crests to pass a fixed point. Longer period swells carry more energy than choppy short-period seas of the same height, because more water mass is moving. A 12-second swell carries roughly twice the energy of a 6-second chop at the same wave height.
Is this formula for deep water or shallow water waves?
This formula applies to deep water waves, where water depth is greater than half the wavelength. In shallow water, wave speed decreases and the formula changes. For coastal engineering in shallow water, use the shallow water wave power formula which accounts for the local depth and wave group velocity.
Official sources
- NOAA National Data Buoy Center: Wave height and period data.
- International Renewable Energy Agency (IRENA): Ocean Energy Resource Assessment.
- US Department of Energy, Water Power Technologies Office: Marine and Hydrokinetic Technology.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.