Difference Between Absolute and Relative Height. One of the parameters that characterizes an object’s position in space is height. It shows the distance measured vertically from a given reference point to the desired point. Let’s explore two aspects of this measurement: absolute height and relative height.


Absolute height refers to the height expressed as the distance from sea level to the object of interest.

Relative height is a coordinate associated with any chosen reference point other than sea level.


The main difference between absolute height and relative height lies in the reference point chosen. In the case of absolute height, the reference point is the horizontal plane of the sea, assuming it is in a calm state. If the object is above this level, the absolute height value is positive, and if it is below this surface, the value is negative.

Absolute height is typically used to mark the elevations of mountains, flat areas, and other elements of the terrain on plans and maps. This ensures maximum consistency in measurements. However, sea levels are not the same everywhere. Therefore, scientists agree on which surface to consider as zero.

In Russia and neighboring countries, for instance, height measurements are made with respect to the level corresponding to the Baltic Sea. Even in areas far from these bodies of water, special markers are installed with their absolute coordinates indicated. By using these reference points, one can calculate the vertical distance from the initial sea level to any desired point.

Now, let’s delve into relative height. Here, the reference point is chosen arbitrarily. For example, you can calculate the height of a hill relative to its base. In this case, there is a possibility that measurements taken from different sides of the natural object may not match. Relative height, which shows the distance between closely located points, is often more important in practice than absolute height, which is related to a distant sea.

The instrument used for height determination is called a level. Its simplest version consists of a meter-long rod with a short crosspiece attached perpendicularly at the top. The crosspiece allows the level to be positioned perfectly vertically. When measuring height, for example, on a hill, the apparatus is placed at the base of the hill. By extending the short crosspiece towards the slope and aligning it, you mentally draw a line continuing horizontally.

The endpoint (which is one meter above the base) becomes the next reference point for the level. The same steps are repeated, and after reaching the summit of the object, calculations are made to determine the relative height of the hill.