Wave Height & Period Calculator
Calculate significant wave height, period, and wavelength from wind speed, fetch distance, and duration using the SMB method.
Inputs
knots
mi
hours
Results
Significant Wave Height (Hs)
1.98 m
≈ 13 smartphones
Wave Period5.7 s
Wavelength50 m
Max Wave Height (Hmax)3.69 m
Wave Steepness (H/L)0.04
Beaufort Scale5
How to Use This Calculator
- Enter Wind Speed, Fetch Distance, and Wind Duration.
- Review the Significant Wave Height (Hs) (m) result.
- Use Wave Period (s) and Wavelength (m) to inform your decision.
How the result changes with Wind Speed
| Wind Speed | Significant Wave Height (Hs) |
|---|---|
| 13 | 1 m |
| 43 | 5.45 m |
| 78 | 11.25 m |
| 108 | 16.55 m |
What each input means
- Wind Speed
- Sustained wind speed in knots measured at 10 m above sea surface.
- Fetch Distance
- Unobstructed distance over water that the wind blows in a constant direction.
- Wind Duration
- How long the wind has been blowing at the given speed. Shorter durations limit wave development.
How this is calculated
Worked example, using the default values
- Identify Input ParametersWind Speed = 20, Fetch Distance = 200, Wind Duration = 6 = 3 input(s) provided
- Calculate Significant Wave HeightSignificant Wave Height1.98 = 1.98
- Calculate Wave PeriodWave Period5.7 = 5.7
- Calculate WavelengthWavelength50 = 50
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