OceanCalc

True from Magnetic Heading — Kilometers

True heading = magnetic heading + easterly variation (subtract westerly).

Last updated: March 28, 2026

Author: OceanCalc Editorial Team · Publisher: Albor Digital LLC

Page focus

Use this view when you need kilometer-focused results from the True from Magnetic Heading. Enter your values above; results stay synchronized with the full tool.

True from Magnetic Heading

Result

True heading (°)

280

Formula

True = Magnetic + variation (east positive)

Overview

Use the True from Magnetic Heading for fast, reliable maritime math—built on standard nautical relationships with straightforward inputs.

How to use

Start by filling in the fields for the True from Magnetic Heading; the page recalculates as you type so you can iterate through options in one place.

Formula

The relationship behind this tool is: True = Magnetic + variation (east positive)

Variation (declination) converts between magnetic and true directions. Deviation is additional ship-specific error.

Practical use cases

Typical uses for the True from Magnetic Heading 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 True from Magnetic Heading.
  • 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

  • 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?

    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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