The SW6816 Square Kilometre

SW6816 National Grid Square

Based in the South West English Region.

SW6816 is within the post town of Helston, Cornwall.

The square is within Cornwall council.

The Point of Origin (0,0) is 168.76 Kilometres away. This is where the National Grid starts around 80 kilometres west of the Isles of Scilly.

Ordnance Survey Maps for SW6816

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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 SW6816 and the vertical and horizontal line divides the square into four quadrants

Dividing the SW6816 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 , 68 and 16

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 + 68 + 3 + 16 + 5 would give you the six figure grid reference of SW683165

SW	68		16
SW	68	3	16	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	49.998903	-5.239319	168000	16000
South East Corner	49.998903	-5.224785	169000	16000
North West Corner	50.008271	-5.239319	168000	17000
North East Corner	50.008271	-5.224785	169000	17000