OceanCalc

Wave Height Calculator — Kilometers

Estimate significant wave height from wind speed. Uses simplified empirical relationship for open water.

Last updated: March 28, 2026

Author: OceanCalc Editorial Team · Publisher: Albor Digital LLC

Page focus

Use this view when you need kilometer-focused results from the Wave Height Calculator. Enter your values above; results stay synchronized with the full tool.

Wave Height Calculator

Result

Approx. wave height (m)

9.6

Approx. wave height (ft)

31.5

Formula

Simplified: H ≈ 0.024 × wind_speed_kn² (open water, fetch-limited)

Overview

Use the Wave Height Calculator for fast, reliable maritime math—built on standard nautical relationships with straightforward inputs.

How to use

Start by filling in the fields for the Wave Height Calculator; the page recalculates as you type so you can iterate through options in one place.

Formula

The relationship behind this tool is: Simplified: H ≈ 0.024 × wind_speed_kn² (open water, fetch-limited)

Significant wave height is approximated from wind speed. Actual height depends on fetch, duration, and depth.

This uses a simplified empirical relationship. Real wave height varies with fetch (distance over water), wind duration, and water depth.

Practical use cases

Typical uses for the Wave Height Calculator include passage planning, briefing crew, converting instrument readouts to chart units, and double-checking mental math when fatigue or weather make errors more likely.

Tips for accuracy

  • Confirm that the units you enter match your chart, GPS, or instrument readout before relying on the Wave Height Calculator.
  • In rough weather or poor visibility, cross-check important results with a second method or a crew member.
  • Treat simplified models (wave height, radar horizon, etc.) as estimates—real conditions vary with fetch, refraction, and equipment.

Practical examples

  • 20 kn wind → ~9.6 m waves (open ocean)
  • 10 kn → ~2.4 m
  • 30 kn → ~21.6 m (storm)

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?

    This calculator uses standard maritime formulas and practical approximations where noted. It is suitable for planning and cross-checks; always verify safety-critical decisions with official references and local conditions.

  • Can I use this on mobile?

    Yes. OceanCalc tools are responsive and work on phones and tablets for quick checks on deck or in the cockpit.

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Learn More

Results are estimates for educational purposes only and should not be used for real navigation decisions.

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