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Ordnance Survey maps: grid references, scale and symbols
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Ordnance Survey (OS) maps let you find exact places and measure real distances. Two skills unlock them: grid references and scale.
Four-figure grid references
OS maps are covered in a grid of squares, each 1 km across.
Eastings are the lines numbered along the bottom. Northings are the lines numbered up the side.
Give the easting first, then the northing: 'along the corridor, then up the stairs'. Use the bottom-left corner of the square. Square 4523 has easting 45 and northing 23.
Eastings are the lines numbered along the bottom. Northings are the lines numbered up the side.
Give the easting first, then the northing: 'along the corridor, then up the stairs'. Use the bottom-left corner of the square. Square 4523 has easting 45 and northing 23.
Six-figure grid references
To be more exact, split each square into tenths.
A church 7 tenths east of easting 45 and 4 tenths north of northing 23 is at 457234.
The first three figures are the easting; the last three are the northing.
A church 7 tenths east of easting 45 and 4 tenths north of northing 23 is at 457234.
The first three figures are the easting; the last three are the northing.
Scale and symbols
Scale shows how much smaller the map is than real life.
On a 1:50,000 map, 2 cm = 1 km. On a 1:25,000 map, 4 cm = 1 km.
To find a real distance: measure on the map, then multiply by the scale. 6 cm on a 1:50,000 map is 6 x 50,000 = 300,000 cm = 3 km.
OS maps use symbols (shown in the key), such as a blue P for parking and a cross for a place of worship.
On a 1:50,000 map, 2 cm = 1 km. On a 1:25,000 map, 4 cm = 1 km.
To find a real distance: measure on the map, then multiply by the scale. 6 cm on a 1:50,000 map is 6 x 50,000 = 300,000 cm = 3 km.
OS maps use symbols (shown in the key), such as a blue P for parking and a cross for a place of worship.
On a 1:25,000 map, two villages are 10 cm apart. How far apart are they really?
- On a 1:25,000 map, 4 cm = 1 km.
- 10 cm divided by 4 cm per km = 2.5.
- So the real distance is 2.5 km.
Answer: 2.5 km
Easting first, then northing (along the corridor, up the stairs). Four figures find a 1 km square; six figures find a point to the nearest 100 m. On 1:50,000 maps 2 cm = 1 km; on 1:25,000 maps 4 cm = 1 km.
The interactive lesson includes the diagrams for this topic.
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