True from Magnetic Heading
Updated recently with improved calculation accuracy and expanded examples.
True heading = magnetic heading + easterly variation (subtract westerly).
Last updated: August 28, 2026
Author: OceanCalc Editorial Team · Publisher: Albor Digital LLC
True from Magnetic Heading
Result
True heading (°)
280
Formula
True = Magnetic + variation (east positive)What is the True from Magnetic Heading?
True heading = magnetic heading + easterly variation (subtract westerly).
heading
Heading is the direction a vessel's bow is pointing, normally expressed as an angle clockwise from north.
magnetic variation
Magnetic variation is the angular difference between true north and magnetic north at a given location and time.
Related Maritime Calculators
Overview
Heading is the direction a vessel's bow is pointing, normally expressed as an angle clockwise from north. A True from Magnetic Heading 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
- Magnetic variation — Magnetic variation is the angular difference between true north and magnetic north at a given location and time.
- True from Magnetic Heading — Heading is the direction a vessel's bow is pointing, normally expressed as an angle clockwise from north.
- Formula — Variation (declination) converts between magnetic and true directions.
- How to use — Fill the inputs for the True from Magnetic Heading; the tool recalculates live as you edit.
How to use
Fill the inputs for the True from Magnetic Heading; the tool recalculates live as you edit.
Formula
Core relationship: True = Magnetic + variation (east positive)
Variation (declination) converts between magnetic and true directions. Deviation is additional ship-specific error.
Practical use cases
True from Magnetic Heading: 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 True from Magnetic Heading.
- 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
- 270° mag, 10°W variation → enter −10 for var → 260° true
Frequently Asked Questions
What about deviation?
Apply deviation from the compass card after magnetic correction, or combine into a single correction per your procedure.
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.
Results are estimates for educational purposes only and should not be used for real navigation decisions.