Sailing VMG Calculator
Velocity Made Good (VMG) is the component of your sailing speed that is directed directly upwind or downwind toward your destination. Because sailboats cannot sail directly into the wind, they tack at an angle, and VMG measures how efficiently that tacking translates into progress toward the mark. Upwind VMG = Boat speed x cos(True Wind Angle). Downwind VMG = Boat speed x cos(180 - TWA). Enter your boat speed and the true wind angle (TWA) to find your VMG upwind and downwind. Use this to compare tacking angles and find the optimal course for your boat's polar curve.
VMG formula
Upwind VMG = Boat speed * cos(TWA)
Downwind VMG = Boat speed * cos(180 - TWA)
Optimal TWA maximizes VMG for a given wind strength.
Example: 6.5 kts at TWA 42 deg: VMG up = 6.5 * cos(42) = 6.5 * 0.743 = 4.83 kts
TWA is the angle between the boat's heading and the true wind direction (not apparent wind). Range 0-180 degrees.
Optimizing VMG in practice
- Modern performance instruments display VMG directly using GPS speed and wind instruments.
- Optimal VMG angles differ by wind strength; in light air, foot off and go faster; in heavy air, point up and slow slightly.
- Polar diagrams provided by boat designers give theoretical optimal VMG angles for all wind speeds.
- For cruising boats, comfort and sea state often matter more than maximum VMG.
Sailing VMG: frequently asked questions
What is velocity made good (VMG)?
VMG is the component of your boat's velocity that is directed toward or away from the wind (or a mark). When sailing to windward, VMG = boat speed * cos(angle to wind). You maximize VMG by finding the optimal angle between pointing high (slow boat, bad VMG) and bearing away (fast boat, poor angle).
How do I use VMG to choose a tacking angle?
The optimal tacking angle maximizes VMG toward the windward mark. On many boats this is between 30 and 45 degrees true wind angle (TWA). Calculate VMG at several TWAs and choose the one with the highest value. Polar diagrams (speed-TWA curves) give this for your specific boat.
What is the difference between TWA and AWA?
True wind angle (TWA) is the angle between your course and the true wind direction. Apparent wind angle (AWA) is the angle you feel on the boat, combining true wind and boat motion. Most instruments display AWA; you need to subtract the boat's effect to get TWA. VMG calculations use TWA.
What is a good upwind VMG for a sailboat?
A well-tuned cruising sailboat might achieve an upwind VMG of 4-5 knots while sailing at 6 knots at a 40-degree TWA. Racing boats optimized for upwind work can achieve VMG of 6+ knots. VMG depends heavily on wind strength, boat type, and crew skill.
Does VMG apply downwind as well?
Yes. Downwind VMG = boat speed * cos(180 - TWA). Sailing dead downwind (TWA = 180) in light air is often slower VMG than broad reaching at 150-160 degrees. Gybing at an optimal angle downwind is the mirror image of tacking to windward.
Official sources
- National Geospatial-Intelligence Agency: Bowditch American Practical Navigator.
- US Sailing Association: US Sailing.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.