The SW6423 Square Kilometre

SW6423 National Grid Square

Based in the South West English Region.

SW6423 is within the post town of Helston, Cornwall.

The square is within Cornwall council.

The Point of Origin (0,0) is 165.60 Kilometres away. This is where the National Grid starts around 80 kilometres west of the Isles of Scilly.

Ordnance Survey Maps for SW6423

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Map Series	link	Ordnance Survey
Explorer 1:25,000 103 Lizard, Falmouth and Helston	Shop for this map on amazon.co.uk	Buy Direct from the Ordnance Survey
Landranger 1:50,000 203 Land's End & Isles of Scilly	Shop for this map on amazon.co.uk	Buy Direct from the Ordnance Survey

This extract is taken from the Ordnance Survey six-inch to the mile series surveyed from 1888-1913. The scale is 1:10,560.

The Square overlayed over the map represents the extent of SW6423 and the vertical and horizontal line divides the square into four quadrants

Dividing the SW6423 Square to get a six figure Grid Reference

A helpful reminder for calculating grid references is across the landing and up the stairs.

For example if your house was located in a square that in the fourth square across and sixth square up and you wanted to work out its six figure grid refence.

First, You would divide the four figure grid reference into three parts. SW , 64 and 23

Count across starting with zero. This would give you three. Make a note that X for Across (A Cross) = 3.

Count up starting with zero. This would give you five. Make a note that Y = 5.

So to put it together SW + 64 + 3 + 23 + 5 would give you the six figure grid reference of SW643235

SW	64		23
SW	64	3	23	5

A six figure grid reference would be accurate to 10 metres. To achieve a greater level of accuracy this 10 metre square would be divided into a grid 10 by 10 and the process repeated.

This would produce an 8 figure grid reference that would be accurate to a square metre!

Corner	Latitude	Longitude	Easting	Northing
South West Corner	50.060185	-5.299357	164000	23000
South East Corner	50.060185	-5.284793	165000	23000
North West Corner	50.069560	-5.299357	164000	24000
North East Corner	50.069560	-5.284793	165000	24000