Bearing & Heading Calculator

True / magnetic / compass / back bearings between two points with a live compass rose.

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From

Magnetic declination (°E positive)

Compass deviation (°E positive)

251.8°T

WSW

True bearing

251.79°T

WSW

Magnetic bearing

251.79°M

True − 0° declination

Compass bearing

251.79°C

Magnetic − 0° deviation

Back bearing (reciprocal)

71.79°T

ENE

What's the difference between true, magnetic, and compass bearing?

True bearing (°T) is measured clockwise from geographicnorth. It's what a great-circle calculation produces and what appears on a paper chart's compass rose ring labelled "true".

Magnetic bearing (°M) is measured from magnetic north. The difference between the two, magnetic declination (or variation), varies by position and changes slowly over time. East declination is added when converting magnetic → true, so to go true → magnetic you subtract it.

Compass bearing (°C)is what your boat's compass actually reads. It differs from the magnetic bearing by deviation, a per-vessel error caused by nearby ferrous metal and electrical fields. Deviation is heading-dependent and lives on the boat's deviation card.

The "Auto estimate" declination button uses a centered-dipole approximation — it's only a rough hint. For real navigation, use a current WMM/IGRF value (e.g. NOAA's online calculator).

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About Bearing & Heading Calculator

The Bearing & Heading Calculator works out the direction from one point to another and converts between true, magnetic, compass, and back bearings. Enter your two positions, and it computes the initial bearing while applying variation and deviation so you can move cleanly between chart values and what you steer on the compass. A live compass rose shows the result visually, making it easy to sanity-check the angle and its reciprocal.

It is built for sailors, navigators, surveyors, pilots, and students who routinely juggle true and magnetic references. Everything runs entirely in your browser, so your coordinates and headings never leave your device and nothing is uploaded to a server. It is completely free, needs no sign-up, and gives instant results as you type.

How to use

Enter the coordinates or values for your starting and destination points.
Input the local magnetic variation and any compass deviation.
Read the calculated true, magnetic, and compass bearings.
Check the back (reciprocal) bearing and confirm it on the live compass rose.

Features

True, magnetic, and compass bearing conversion
Instant back (reciprocal) bearing calculation
Live compass rose visualization
Applies variation and deviation corrections
Runs privately in your browser
Free with no sign-up required

Frequently asked questions

Does my position data stay private?

Yes. All calculations happen locally in your browser, so your coordinates and headings are never uploaded or stored on any server.

What is the difference between true, magnetic, and compass bearings?

True bearings reference geographic north, magnetic bearings reference magnetic north (true adjusted for variation), and compass bearings further account for your vessel's deviation.

How is the back bearing calculated?

The back, or reciprocal, bearing is simply 180 degrees from the forward bearing: add 180 if the value is under 180, otherwise subtract 180.

Where do I find variation and deviation values?

Magnetic variation is printed on nautical charts and compass roses for your area, while deviation comes from your vessel's own deviation card.

Is the tool free to use?

Yes, it is completely free with no account or installation needed, and it works directly in any modern browser.

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