Wave Height Calculator
Updated recently with improved calculation accuracy and expanded examples.
Estimate significant wave height from wind speed. Uses simplified empirical relationship for open water.
Last updated: August 28, 2026
Author: OceanCalc Editorial Team · Publisher: Albor Digital LLC
Wave Height Calculator
Result
Approx. significant wave height (m)
2.54
Approx. significant wave height (ft)
8.3
Formula
Simplified SMB-style estimate: H ≈ 0.024 × U², where U is wind speed in m÷s.Model note: This calculator estimates significant wave height using an empirical wind-wave relationship; actual sea state can differ with fetch, duration, swell, and local conditions.
What is the Wave Height Calculator?
Significant wave height is the average height of the highest one-third of waves. It is commonly reported in marine forecasts.
This simplified estimate assumes a fully developed sea in open water; actual wave height also depends on fetch, wind duration, water depth, and other sea-state conditions.
significant wave height
Significant wave height is approximately the average height of the highest one-third of waves in a sea state, not the largest single wave.
Related Maritime Calculators
Overview
Significant wave height is approximately the average height of the highest one-third of waves in a sea state, not the largest single wave. A Wave Height Calculator is used in maritime navigation to perform precise calculations based on established nautical formulas. This tool allows you to apply your inputs to the stated nautical relationships using accurate and standardized methods.
Key takeaways
- Wave Height Calculator — Significant wave height is approximately the average height of the highest one-third of waves in a sea state, not the largest single wave.
- How to use — Fill the inputs for the Wave Height Calculator; the tool recalculates live as you edit.
How to use
Fill the inputs for the Wave Height Calculator; the tool recalculates live as you edit.
Formula
Core relationship: Simplified SMB-style estimate: H ≈ 0.024 × U², where U is wind speed in m/s.
Significant wave height is approximated from wind speed. Actual height depends on fetch, duration, and depth.
This simplified estimate assumes a fully developed sea in open water; actual wave height also depends on fetch, wind duration, water depth, and other sea-state conditions.
Practical use cases
Wave Height Calculator: passage planning, crew briefings, instrument-to-chart unit checks, and verifying mental math when tired or in rough weather.
Tips for accuracy
- Match input units to your chart, GPS, or instrument before trusting the Wave Height Calculator.
- Cross-check important outputs with a second method or crew when visibility or motion is poor.
- Treat simplified models (waves, radar horizon, etc.) as estimates; real conditions vary.
Practical examples
- 10 kn wind → ~0.64 m significant wave height
- 20 kn wind → ~2.54 m significant wave height
- 30 kn wind → ~5.72 m significant wave height
Frequently Asked Questions
What is significant wave height?
Significant wave height is the average height of the highest one-third of waves. It is commonly reported in marine forecasts.
Why does wave height vary?
Wave height depends on wind speed, fetch (distance the wind blows over water), duration, and water depth. Shallow water limits wave growth.
How accurate is this calculator?
It uses standard maritime formulas and noted approximations. Use it for planning and checks; confirm safety-critical decisions with official sources.
Can I use this on mobile?
Yes. Layouts are responsive for phones and tablets on deck or in the cockpit.
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These calculations are based on standard maritime navigation formulas used in seamanship, chart navigation, and marine route planning.
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Results are estimates for educational purposes only and should not be used for real navigation decisions.