How to Convert OS grid references to GPS waypoints

[MrToad]

Hi Mr Toad here,

is there anybody out there who knows how to fairly accurately convert OS grid reference co-ordinates to GPS waypoints.

i.e.OS Grid: SE 078046 equates to GPS waypoint: SE 07816 04684

It seems as though you take the first three digits of the OS grid reference for the first part of the GPS waypoint & add two more digits.

Then take the last three digits of the OS grid reference for the second part of the GPS waypoint and again add two more digits.

Can those extra digits be two O's? or is there a more accurate way of doing it?

Heres hoping you can help,

Mr Toad

[haematocephalus]

Grid references always refer to squares.

SE 078 046 is a grid reference that specifies a 100-metre by 100-metre square.

SE 0785 0465 is a grid reference that specifies a 10-metre by 10-metre square, roughly in the middle of the 100-metre square SE 078 046.

SE 07855 04655 is a grid reference that specifies a 1-metre by 1-metre square, roughly in the middle of the 10-metre square SE 0785 0465.

So if you want to make a waymark from grid ref SE 078 046 you can choose to put your waymark in the middle of the 100-metre square (SE 07855 04655), at the bottom-left of the 100-metre square (SE 07800 04600), at the top-right of the 100-metre square (SE 07899 04699) etc. etc.

Hope that makes sense

Martin


Martin Harvey

[Paul mabbott]

Haematocephalus has explained that very well but it may help your understanding to say that the first half of the numbers are eastings (i.e. longitude) the second half of the numbers are northings (i.e. latitude). The more figures there are, the more precise the location.