Find the coordinates of every square

within the world-wide German Naval Grid from WWII.

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What is this about?

During WWII the German Navy used its own classified grid system to disguise, simplify and compress positions at sea. The grid consisted of 536 large squares that covered almost all sea areas of the world. Today it is difficult to convert these positions from war diaries and other documents into usable geographical coordinates.

This tool uses a completely different approach. There is no lookup table for squares and coordinates, but a complex mathematical model to calculate the coordinates of all squares. There are indeed some coordinates stored within the core library, especially for irregular quadrants, but this is kept to a minimum with the goal of calculating as much as possible.

There are other services and tools, which convert grid squares; however they are limited to a subset of squares and may be inaccurate.

What are the features?

This tool will convert all* grid squares to geographical coordinates. It can also reverse search and retrieve the square for any given coordinate. The following details for each square are displayed:

  • Center coordinate for regular and irregular squares
  • Height, mean width, max width and min width
  • Type of square: regular, irregular (partial), irregular (polygonal)
  • Rendering of the requested square in Open Street Map

Furthermore you can download the displayed square as a KML file for Google Earth or Maps depicting the borders and center coordinate.

See an example » See what's missing »

* 11 of the 536 large squares are not fully proven

How can you help?

If you have information or sources that might help resolve the inner structure of the remaining uncertain squares or if you discovered bugs or errors, you can get in contact with me.

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What is uncertain?

Currently 11 of the 536 large squares are not fully proven. Although their inner structure could be reconstructed, there is still reasonable doubt.

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How did I do that?

If you want to know more about this project, you'll find a detailed article about the development process, resources, thoughts and considerations on the About page.

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