Contour interval
Overview
Contour interval is the vertical distance in elevation between adjacent contour lines on a topographic map. It determines how finely elevation changes are represented.
Key points
- The contour interval is usually stated in the map legend.
- Smaller intervals show elevation changes in more detail.
- Larger intervals can make maps less cluttered but less granular.
- Understanding intervals helps hikers estimate climb and descent.
- Steep slopes appear where contour lines are closely spaced.
- Different maps of the same area may use different contour intervals.
Details
On a topographic map, contour lines connect points of equal elevation. The contour interval specifies how much vertical distance separates one line from the next. For example, if the interval is 20 metres, each contour line represents a 20-metre change in elevation from the one adjacent to it.
This information is typically printed in the map legend or margin. Knowing the contour interval helps hikers translate map patterns into approximate real-world elevation changes. For instance, counting how many lines are crossed along a trail can provide a rough estimate of total ascent or descent.
Maps with small contour intervals, such as 10 metres, can reveal fine-scale features like small ridges and depressions but may appear more crowded. Maps with larger intervals reduce clutter but may smooth out minor details.
Recognizing the contour interval also supports interpretation of slope steepness. Where lines are close together, the terrain is steeper; where they are spaced widely, the terrain is more gradual. This can influence route choices and expectations for effort.
Different mapping products of the same region may use different contour intervals, so checking the legend for each map is a standard part of navigation preparation.
Related topics
Disclaimer: thruhikingwiki.com is an independent, informational reference only. It is not an official source for any trail association, land manager, park, agency, or guide service. Nothing on this site is legal, safety, medical, navigation, or professional advice, and it does not replace formal training or certified instruction. Thru-hiking and backcountry travel involve significant risk. Local regulations, land manager rules, and manufacturer instructions always take priority. You are solely responsible for your planning decisions, safety practices, and compliance with applicable laws. Use this site at your own risk.
Illustrative hiking footage
The following external videos offer general visual context for typical hiking environments. They are not official route recommendations, safety instructions, or planning tools.