Luftwaffe Planquadrat Map Converters
GNMV (post–April 1943) & JMN
© Ron Birch 2025
A Planquadrat or Grid Square, was the description of a location using one of the German mapping systems. At the start of WWII, the Luftwaffe was using the map reference system Gradnetz or Grid Network, also known as Gradnetzmeldeverfharen
(GNMV)
or Grid Network Reporting Method, where the map of the world was broken down into quadrants, and then further subdivided into ever smaller units measured in degrees, minutes and seconds of latitude and longitude.
This reporting network was already in use by the Luftwaffe before the war and was maintained almost unchanged until the end of April 1943. The system was refined from 1st May 1943, with the introduction of more subdivisions of the smaller units and also by the introduction of a new network, the
Jagermeldenetz
(JMN)
or Fighter Reporting Network, to assist fighter aircraft and anti-aircraft units against the increasingly effective Allied bombing campaigns. You can read our explanation of how the systems worked
here
.
The converters below can be used to convert planquadrat references to decimal co-ordinates or vice-versa, and display them on the embedded map. The data can be opened directly in Google Maps, or exported as .kml or .geoJSON files to be imported into your own mapping systems such as Google Earth.
The GNMV converter only works for post 1st May 1943 planquadrats, but if you want to enter earlier versions, selecting 5 for both Melde and Arbeit should be fairly close. The converter is capable of working in both northern and southern hemispheres, but we have decided to make only the northern hemisphere available until we are sure it is working correctly. The default settings are the location of the crash site of Halifax JB837.
Convert Grid → Coordinates (GNMV)
ZZG (2–3 digits, max 189)
Hemisphere
Ost
West
Groß (XY)
Mittel (1–8)
1
2
3
4
5
6
7
8
Klein (1–9)
1
2
3
4
5
6
7
8
9
Melde (1–9)
1
2
3
4
5
6
7
8
9
Arbeit (a–i)
a
b
c
d
e
f
g
h
i
Export level
Arbeit
Melde
Klein
Mittel
Groß
Convert Grid
→ Co-ordinates
Export
to KML
Export
to GeoJSON
Convert Coordinates → Grid (GNMV)
Latitude
Longitude
Convert Co-ordinates
→ Grid
Convert Grid → Coordinates (JMN)
ZZG (2–3 digits, max 189)
Hemisphere
Ost
West
Half
Nord
Süd
Mittel (AA..UU)
Klein (1–9)
1
2
3
4
5
6
7
8
9
Melde (1–9)
1
2
3
4
5
6
7
8
9
Arbeit (a–i)
a
b
c
d
e
f
g
h
i
Export level
Arbeit
Melde
Klein
Mittel
Jagd
Convert Grid
→ Co-ordinates
Export
to KML
Export
to GeoJSON
Convert Coordinates → Grid (JMN)
Latitude
Longitude
Convert Co-ordinates
→ Grid
This page was written by Ron Birch (q.v. Acknowledgements) using the information on the Luftwaffe Map Reference page of this website to teach ChatGPT the rules of the GNMV and JMN systems. ChatGPT then performed the mathematics and returned the scripts which are embedded in this page. It took many iterations before ChatGPT got it right. We have exhaustively tested the conversion tools, but would welcome any feedback, so if you find any errors during your own research, please report them to me at
mail@prwg.co.uk
.