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Great circle azimuth bearing and range calculator (with magnetic north)

Input your home lat/long and also the distant lat/long. Results are range in km, nautical and statute miles and azimuth bearing both relative to true north and (approx) relative to local magnetic north at home location.

Longitude: 0.0 to +180.0 deg East, 0.0 to -180.0 deg West (use decimals. NOT deg/min/sec)
Latitude: +North or -South. Magnetic bearing is not available beyond +/-60 deg latitude.

Input data in green boxes:

Home latitude (degN+, S-)		Distant latitude (degN+, S-)
deg min sec		deg min sec

Home longitude (deg E)		Distant longitude (deg E)
deg min sec		deg min min

Output data in blue boxes:

Azimuth (deg E relative to true north)	Azimuth (deg E relative to magnetic north)	Range (km)


Range (statute miles)	Range (nautical miles)	Rhumb az (deg E true)

The azimuth angle relative to magnetic north is not available beyond +/- 60 deg latitude due to increasing inaccuracy in my earth's magnetic field model. To get true north here I suggest using a GPS receiver and walking in one direction for a while, then read the true bearing of that line of walking.

The azimuth angle relative to magnetic north calculated above is approximate, based on my simplified earth's magnetic field model.

This page has been put on because so many people were finding the satellite dish pointing azimuth and elevation page when they were really searching for a terrestrial great circle azimuth and range calculator.

If you need a BACK BEARING from the distant site back to home do the calculation again, you can't just add 180 deg. The reason for this is that lines of longitude are not parallel to one another, particularly towards the north and south pole. The errors are small however near the equator and over short distances.

Go here if you want to see a satellite photo or image or imagery of your house or home. The free satellite photo images and maps are provided by a Google map server and using the latitude longitude you may visualise the positions.

Comment received 11 Sept 2004 about earth radius in km as used in great circle calculation. Range per degree amended to correspond to ellipsoidal quadratic mean radius in response to comment by Kaimbridge

"Greetings Eric!

I tried your "Great circle azimuth bearing and range calculator" and have a suggestion for a better "great circle radius": You
use "111.15/deg" which corresponds to a radius of about 6368.4259

What--if any--equation/theory is it based on? None - it was just my approximation for earth radius.

A much better "great circle radius" would be the ELLIPSOIDAL (not just elliptical) quadratic mean radius, which equals

[.25 * (3a^2 + b^2)]^.5, which, for Earth (a = 6378.135, b = 6356.75),

works out to 6372.795477598, or about 111.226264/deg

~Kaimbridge~"

There may be errors; any problems or comments please e-mail me Eric Johnston

Last revisions:
14 Jun 2003, statute and nautical miles added, magnetic field database updated. 11 Sept 2004 magnetic field database updated. Magnetic field model updated 17 April 2006. Heading and link to home page changed to match main website style 1 April 2008. 24Nov2008: Sequence of lat long for the input location variables reversed.

Updated 7 August 2015 for small screen devices

Updated 16 Sept 2015. To make rhumb line bearing calculation result in range 0 to 360 rather than +/-180.

Updated 30 Jan 2015: Added seconds box to each of the input variables.

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Updated 21 Mar 2019 HTML5