Grid references are a fundamental navigation skill that every outdoor adventurer should master. They allow you to pinpoint any location on a topographic map and communicate that position to others with precision.

What is a Grid Reference?

A grid reference is a set of numbers that identifies a specific location on a map using the grid lines printed on topographic maps. In Australia, we use the Map Grid of Australia (MGA) system based on Universal Transverse Mercator (UTM) coordinates.

The Grid System

Topographic maps are covered with a grid of vertical and horizontal lines:

• Eastings - Vertical lines numbered from west to east (the first half of your grid reference)
• Northings - Horizontal lines numbered from south to north (the second half)

Remember: "Read Right, then Up" or "Along the corridor, then up the stairs"

4-Figure Grid Reference

The simplest form, identifying a 1km × 1km grid square:

1. Find the vertical grid line to the LEFT of your point - note its number (e.g., 45)
2. Find the horizontal grid line BELOW your point - note its number (e.g., 32)
3. Combine them: 4532

6-Figure Grid Reference

More precise, identifying a 100m × 100m area:

1. Start with the 4-figure reference (45, 32)
2. Estimate tenths across to your point from the left line (e.g., 7 tenths = 7)
3. Estimate tenths up from the bottom line (e.g., 4 tenths = 4)
4. Insert these: 457324

8-Figure Grid Reference

The most precise, identifying a 10m × 10m area. Follow the same process but estimate to hundredths. Used for precise locations like helicopter landing zones or specific features.

Using a Romer

A romer is a small scale printed on the edge of a compass or as a separate tool. It helps you accurately measure the tenths within a grid square rather than estimating by eye. Place the corner of the romer on your point and read off the precise values.

Common Mistakes to Avoid

• Reading northings before eastings (always go RIGHT then UP)
• Using the wrong number of digits (6-figure refs must have 6 digits)
• Forgetting to include the full grid reference including zone information for distant locations
• Not specifying which map your reference relates to

Practical Applications

• Route cards - Document waypoints with grid references
• Emergency location - Give rescuers your exact position
• Meeting points - Arrange precise rendezvous locations
• Recording features - Log POIs for future reference

Grid references are a timeless skill that works even when technology fails. Practice regularly until reading and giving grid references becomes second nature. It's a skill that could save your life in an emergency.