True from Magnetic Heading
Updated recently with improved calculation accuracy and expanded examples.
True heading = magnetic heading + easterly variation (subtract westerly).
Last updated: April 22, 2026
Author: OceanCalc Editorial Team · Publisher: Albor Digital LLC
True from Magnetic Heading
Result
True heading (°)
280
Formula
True = Magnetic + variation (east positive)Ad slot — after calculation result
Use this calculation together with proper navigation tools to improve route accuracy and on-water decision making.
What is the True from Magnetic Heading?
True heading = magnetic heading + easterly variation (subtract westerly).
bearing
A bearing is a direction expressed as an angle, usually clockwise from north (true or magnetic), used to describe courses and relative positions.
Related Maritime Calculators
Overview
A bearing is a direction expressed as an angle, usually clockwise from north (true or magnetic), used to describe courses and relative positions. 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
- True from Magnetic Heading — A bearing is a direction expressed as an angle, usually clockwise from north (true or magnetic), used to describe courses and relative positions.
- 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.
Recommended Marine Navigation Tools
These tools are commonly used alongside navigation calculations for real-world sailing and route planning.
- Marine Navigation Parallel Ruler — used for plotting bearings on nautical charts
- Handheld GPS Navigator — provides real-time position and course tracking at sea
- Nautical Chart Plotter Kit — essential for route planning and distance measurement
These are optional tools used by sailors and marine professionals. Choose based on your navigation setup.
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.
Related Navigation Calculations
- Calculate maximum hull speed based on waterline length
- Compute rhumb line distance for constant bearing navigation
- Find initial bearing between two geographic coordinates
- Estimate visual horizon distance based on observer height
- Measure deviation from intended navigation path
- Calculate actual vessel speed considering current and heading
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When to Use This Calculation
- • Planning a navigation route between two points
- • Adjusting course based on wind, current, or drift
- • Verifying distances and bearings during passage planning
- • Supporting manual navigation alongside GPS systems
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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.
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