VMG Calculator
Updated recently with improved calculation accuracy and expanded examples.
Velocity made good toward a mark: boat speed × cos(angle off bow to the mark).
Last updated: August 28, 2026
Author: OceanCalc Editorial Team · Publisher: Albor Digital LLC
VMG Calculator
Result
VMG (kn)
4.6
Formula
VMG = BSP × cos(θ), θ from bow toward markWhat is the VMG Calculator?
Velocity made good toward a mark: boat speed × cos(angle off bow to the mark).
0° = dead ahead; 90° = VMG 0 toward mark along heading (pure beam reach to mark geometry).
VMG
Velocity made good (VMG) is the component of the boat’s speed toward or away from a mark or waypoint, critical for upwind and downwind tactics.
Related Maritime Calculators
Overview
Velocity made good (VMG) is the component of the boat’s speed toward or away from a mark or waypoint, critical for upwind and downwind tactics. A VMG 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
- VMG Calculator — Velocity made good (VMG) is the component of the boat’s speed toward or away from a mark or waypoint, critical for upwind and downwind tactics.
- Formula — VMG is the component of velocity toward a waypoint along your heading-to-mark geometry.
- How to use — Type your figures into the form; outputs refresh so you can compare cases quickly.
How to use
Type your figures into the form; outputs refresh so you can compare cases quickly.
Formula
Core relationship: 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
VMG 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 VMG 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
- 6 kn at 30° → ~5.2 kn VMG
Frequently Asked Questions
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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Popular calculators: Nautical Mile Converter · Knots to km/h Converter · Hull Speed Calculator · Initial Bearing Calculator · Great Circle Distance Calculator · Boat Fuel Consumption Calculator · VMG Calculator
These calculations are based on standard maritime navigation formulas used in seamanship, chart navigation, and marine route planning.
Results are estimates for educational purposes only and should not be used for real navigation decisions.