Key takeaways
- A grid reference identifies a location on a map using the map's grid lines.
- Read eastings (vertical lines) first, then northings (horizontal lines) — 'along the corridor, up the stairs.'
- Estimate tenths within a grid square for precision.
- A six-figure grid reference pinpoints a spot to within about 100 meters.
From the map grid it refers to.
What a grid reference is
A grid reference is a set of numbers (and sometimes letters) that identifies a specific location on a map by referring to the map’s grid lines — the evenly spaced vertical lines (eastings) and horizontal lines (northings) overlaid on it, forming a grid of squares.
How to read and give one
Always read eastings first, then northings — ‘along the corridor, then up the stairs.’ A four-figure reference gives the bottom-left corner of a square (locating the square). A six-figure reference divides each square into tenths, estimating how many tenths across and up your point lies — pinpointing a spot to roughly 100 meters on common topographic maps.
Needing to report a sprained-ankle hiker’s location to rescuers, a navigator reads a six-figure grid reference off their topographic map — eastings then northings, estimating tenths within the square — giving the rescue team a point they can find to within about 100 meters.
Why it’s useful
A grid reference lets you precisely describe, record, and communicate any location — for route planning, marking a campsite, water source, or hazard as a waypoint, reporting your position in an emergency, or relocating a point later. It’s a fundamental land-navigation skill alongside the compass, and relates to coordinate systems like UTM.
The bottom line
A grid reference pinpoints a location on a map using its grid lines — read eastings first, then northings ('along the corridor, up the stairs'), estimating tenths within a square for precision (a six-figure reference locates a spot to ~100 m). It lets you record, share, and relocate any point — for route planning, marking features, or reporting your position to rescuers — a fundamental land-navigation skill.
Frequently asked questions
What is a grid reference?
A grid reference is a set of numbers (and sometimes letters identifying a larger grid zone) that pinpoints a location on a map using the grid of lines printed on it. Maps have evenly spaced vertical lines (eastings) and horizontal lines (northings) forming a grid of squares, and a grid reference tells you which square — and where within it — a point lies, giving a precise, shareable location.
How do you read and give a grid reference?
You always read eastings (the vertical lines, numbered left to right) first, then northings (the horizontal lines, numbered bottom to top) — remembered as 'along the corridor, then up the stairs.' For a four-figure reference you give the easting and northing numbers of the square's bottom-left corner (locating the square). For a six-figure reference, you further divide each grid square into tenths and estimate how many tenths across and up your point is, adding a digit to each — giving a much more precise location (to roughly 100 meters on common topographic maps).
Why are grid references useful?
Because they let you precisely describe, record, and communicate any location on a map — for route planning, marking a campsite, water source, or hazard, reporting your position in an emergency to rescuers, or relocating a point later. A grid reference turns a spot on the map into a compact set of numbers anyone with the same map (or grid system) can find. It's a fundamental land-navigation skill, complementary to using a compass and reading terrain, and related to coordinate systems like UTM.
Sources
- Map reading & navigation — The Mountaineers
- Maps & grids — USGS