The elevation profile shows three numbers from the same altitude data. Each answers a different question.
| Elevation | The range between the highest and the lowest point of the route. Also called altitude difference or altitude range. |
| Ascent | Everything you climb, added up — every uphill stretch summed over the whole route. |
| Descent | Everything you come back down, added up the same way. |
Take a route whose altitude readings run 10 · 13 · 15 · 13 · 11 · 16:
Ascent is almost always larger than elevation. On a hilly route it can be several times larger. That is expected. Elevation describes the terrain, ascent describes the work.
On a loop that finishes where it started, the two ought to match. Often they do not.
Recorded altitude is the cause. A GPS needs good reception from several satellites to fix altitude. Reception at the same spot differs between the outward and the return leg. Each small error adds into the total. The sums drift apart even though the ground did not change.
If a profile looks noisier than the terrain warrants, choose Route › Recompute Elevation from Terrain. It replaces the recorded values with surveyed terrain data. Note that it replaces every point, including good measurements. See why the elevation looks wrong for what terrain data can and cannot tell you.