BYTETOOLS

Maidenhead Grid Locator Converter

Convert latitude and longitude to a Maidenhead QTH locator and back, plus great-circle distance and beam heading between any two grid squares.

A Maidenhead locator (QTH locator) names a square: a 20° × 10° field, a 2° × 1° square, then 5′ × 2.5′ subsquares. Coordinates are WGS-84 and distances use the great circle on a sphere.
JN58td
Locator
6.2 km
Square width
4.6 km
Square height
JN
Field

Square centre and bounding box

JN58td

Centre of the square
48.145833, 11.625000
Centre in DMS
48°8'45.00"N 11°37'30.00"E
South-west corner
48.125000, 11.583333
North-east corner
48.166667, 11.666667

The same point at every length

  • 4 characters — square, 2° × 1°JN58
  • 6 characters — subsquare, 5′ × 2.5′JN58td
  • 8 characters — extended squareJN58td55
  • 10 characters — extended subsquareJN58td55aa

Distance and beam heading between two squares

5414.7
Distance (km)
3364.6
Distance (mi)
288.6°
Beam heading
52.2°
Return heading

Point the antenna at 288.6° (WNW) from the centre of IO91wm; the far station beams back at 52.2° (NE). Headings are true, not magnetic.

What is the Maidenhead Grid Locator Converter?

Amateur radio operators swap Maidenhead locators — JN58td, FN31pr, IO91wm — instead of coordinates, because six characters fit neatly into a contest exchange.

  • Two-way conversion between WGS-84 degrees and 4, 6, 8 or 10 character locators
  • Shows the square's centre, bounding box and real width and height in kilometres
  • Great-circle distance and true beam heading between any two grid squares
  • Reports the return heading so the other station knows where to point
  • A table giving the same position at every locator length
  • Fully offline in your browser — nothing is uploaded

How to use the Maidenhead Grid Locator Converter

  1. 1

    Choose a direction: latitude/longitude to a locator, or a locator back to coordinates.

  2. 2

    Enter the coordinates in decimal degrees or DMS, or type a locator such as JN58td.

  3. 3

    Pick the locator length — six characters is the usual subsquare used on the air.

  4. 4

    Read the square's centre, its corners and its size on the ground.

  5. 5

    Use the two boxes at the bottom to get the distance and beam heading between any two locators.

About the Maidenhead Grid Locator Converter

Amateur radio operators swap Maidenhead locators — JN58td, FN31pr, IO91wm — instead of coordinates, because six characters fit neatly into a contest exchange. This converter turns latitude and longitude into a locator of 4, 6, 8 or 10 characters and decodes any locator back into the square it names, with the centre point and the full bounding box.

It also does the job every VHF operator actually needs: give it two locators and it returns the great-circle distance between the square centres and the beam heading to point the antenna, along with the return heading the other station should use. Headings are true bearings, so apply your local magnetic variation before turning a compass-marked rotator.

Everything is computed locally in your browser. No locators, coordinates or logs are uploaded anywhere, and the page keeps working offline in a field-day tent with no signal.

Frequently asked questions

What is a Maidenhead locator?

It is a compact grid reference used in amateur radio, also called a QTH locator. Two letters name a 20 by 10 degree field, two digits name a 2 by 1 degree square inside it, and two more letters narrow that to a 5 by 2.5 minute subsquare — about 8 km by 4.6 km in the mid latitudes.

How do I find my grid square?

Take the latitude and longitude from your phone or GPS, paste them into the coordinate boxes above, and choose six characters. The tool returns your subsquare and shows exactly which patch of ground it covers, so you can check it matches where you are actually operating from.

How accurate is a distance calculated from two grid squares?

The distance is measured between the centres of the two squares, so it is only as precise as the squares themselves. With six-character locators that means an uncertainty of a few kilometres, which is irrelevant on a 1,500 km contact but noticeable on a short local path.

Is the beam heading magnetic or true?

It is a true bearing, measured clockwise from geographic north. Most rotator displays are also set to true north, but if yours is aligned to magnetic north you need to apply your local variation, which can be several degrees depending on where you are.

Why do some locators have eight or ten characters?

The extra pairs keep subdividing: two digits split the subsquare into a 10 by 10 grid, and two more letters split that again by 24. They are used for microwave work and beacon coordinates where a few metres of positioning matters, but four and six characters cover nearly all normal operating.

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