OceanCalc

VMG Calculator — Examples

Velocity made good toward a mark: boat speed × cos(angle off bow to the mark).

Last updated: March 28, 2026

Author: OceanCalc Editorial Team · Publisher: Albor Digital LLC

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Explore typical numbers with the VMG Calculator. Try the examples in the Examples section below while you vary inputs in the calculator.

VMG Calculator

Result

VMG (kn)

4.6

Formula

VMG = BSP × cos(θ), θ from bow toward mark

Overview

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

How to use

With the VMG Calculator, type your figures into the inputs above—the output refreshes live, making it easy to sanity-check several cases.

Formula

The relationship behind this tool is: VMG = BSP × cos(θ), θ from bow toward mark

VMG is the component of velocity toward a waypoint along your heading-to-mark geometry.

0° = dead ahead; 90° = VMG 0 toward mark along heading (pure beam reach to mark geometry).

Practical use cases

Typical uses for the VMG 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 VMG 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

  • 6 kn at 30° → ~5.2 kn VMG

Frequently Asked Questions

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

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