Topographic map guide

How to Choose a Map Scale

Map scale is the ratio between a distance on the map and the corresponding distance on the ground. The best scale depends on how much detail you need, how much area you want on one sheet and which paper size you plan to use.

What does 1:25,000 mean?

At 1:25,000, one unit on the map equals 25,000 of the same units on the ground. One centimetre on the map therefore represents 250 metres in the real world.

Large scale and small scale

In cartography, 1:10,000 is a larger scale than 1:50,000. The denominator is smaller, so features are shown physically larger and the sheet covers a smaller area.

• Larger scale: less ground area, more room for detail.
• Smaller scale: more ground area, less room for fine detail.

Four questions to ask

How much detail do you need?

If you need to distinguish short route segments, close contour spacing or nearby terrain features, a larger scale is usually easier to read.

How much ground must fit on one sheet?

If you want alternate routes and a wide surrounding area on one sheet, a smaller scale gives more coverage.

A4 or A3?

ISO A4 is 210 × 297 mm and A3 is 297 × 420 mm. At the same map scale, A3 can show a larger area without changing the scale.

How will the map be used?

Detailed compass and grid work places a premium on legibility. Regional planning may benefit more from wider coverage.

Do not confuse map scale with UTM grid spacing

Map scale is a ratio. UTM spacing is the ground distance between selected grid lines. A 1:25,000 map can show 1 km, 5 km or 10 km UTM lines without changing the map scale.

For a direct three-scale comparison, see 1:10,000 vs 1:25,000 vs 1:50,000.