OS map skillsGrid references

A grid of squares helps the map-reader to locate a place. The horizontal lines are called eastings. They are numbered - the numbers increase to the east. The vertical lines are called northings as the numbers increase in a northerly direction.

Things to remember:

• When you give a grid reference, always give the easting first: "Along the corridor and up the stairs".

Four-figure grid references can be used to pinpoint a location to within a square. To find the number of the square:

1. Start at the left-hand side of the map and go east until you get to the bottom-left-hand corner of the square you want. Write this number down.
2. Move north until you get to the bottom-left corner of the square you want. Look at the number of this grid line and add it to the two-digit number you already have. This is your four-figure grid reference.

In this case, the tourist information office is in grid square 4733.

Sometimes it is necessary to be even more accurate. In this case you can imagine that each grid is divided into 100 tiny squares. The distance between one grid line and the next is divided into tenths.

1. First, find the four-figure grid reference but leave a space after the first two digits.
2. Estimate or measure how many tenths across the grid square your symbol lies. Write this number after the first two digits.
3. Next, estimate how many tenths up the grid square your symbol lies. Write this number after the last two digits.
4. You now have a six figure grid reference. In this instance, the tourist information office is located at 476334.