Net elevation gain vs gross elevation gain

The short answer

Net elevation change: take the elevation at the high point of a route and subtract the elevation at the start. One number, one subtraction, and it says nothing about anything that happened in between — including how many times the trail climbed and dropped along the way.

Gross elevation gain, the number most hiking apps report and most people mean when they just say "gain": walk through every point on the route in order, and every time elevation goes up from one point to the next, add that amount to a running total. Downhill stretches are left out of this particular sum entirely — they get their own running total, elevation loss, calculated the same way in the other direction.

On a route that only ever goes up and then only ever comes back down the same way, the two numbers land close together. On a route with any real undulation — dips, rollers, a trail that drops into a drainage and climbs back out more than once — gross gain pulls further and further ahead of net change the more of that undulation there is.

Why a loop can have zero net change and still be a hard day

A loop hike returns to its own starting point by definition, so its net elevation change is always exactly zero — the elevation at the end is, give or take, the elevation at the start. That zero says nothing about the climbing in between. A loop that stays on one ridge the whole way could genuinely be close to flat. A loop that drops into a valley, climbs back out, drops into a second valley, and climbs out of that one too can rack up a large gross gain while its net change sits at zero the entire time, because gross gain only cares about the direction of each individual stretch, never about where the route eventually ends up.

This is the same reason an out-and-back hike usually has gross gain and gross loss that are close to equal, while a point-to-point route walked in one direction can have very different totals for each — the shape of the route decides how far net change and gross gain drift apart, not the length of the hike.

Where each number tends to show up

Net change is cheap to produce: it only needs an elevation for the start and an elevation for the high point, both of which can come from a contour map or a single old survey without anyone walking the trail with a device logging altitude continuously. A lot of older guidebook entries, trailhead signs and quick trail summaries state something closer to net change, sometimes without saying so, because that was the number available to whoever wrote it.

Gross gain needs a record of the whole route, point by point, which is exactly what a GPS track is. A phone logging position and altitude continuously has no choice but to see every dip and rise the trail actually has, so when an app totals up elevation gain from a recorded track, it is almost always reporting the gross figure — every uphill metre counted, none of it netted out against a downhill metre somewhere else on the same route.

A worked example

A loop starts at 800 metres. It climbs to a saddle at 1,100 metres, drops into a basin at 950 metres, climbs a second rise to 1,050 metres, then descends the whole way back to the 800-metre trailhead. Net elevation change, start to high point: 1,100 minus 800, or 300 metres — and that is also the figure a sign might post if it is only quoting "elevation gain" as one subtraction.

Gross elevation gain adds up every uphill segment separately: 300 metres climbing to the saddle, then 100 metres climbing back out of the basin to the second rise, for a gross gain of 400 metres. On a route with more rollers than this one, the gap between 300 and 400 only widens — a trail with a dozen small dips and re-climbs can post a gross gain noticeably higher than its net change, even though the net change never moves, because it depends only on where the route starts and where it tops out.

Which one to use for judging how hard a hike will be

Gross gain is the more honest number for that question, because it reflects every metre your legs actually climbed rather than only the distance between two fixed points on the route. Net change can make a rolling trail look deceptively easy on paper — a net change of 300 metres sounds like a modest climb, right up until the trail turns out to have four separate 100-metre climbs buried inside it that a single subtraction never counted. For planning how long a hike will take or how tiring it will feel, gross gain is the number worth trusting; net change is really only answering a narrower question, which is how much higher the top of the route sits than the bottom.

Things that trip people up

• Reading a loop's net change of zero as "no real climbing" — a loop can have substantial gross gain while its net change stays at zero by definition, because it always ends where it started.
• Comparing a guidebook's net-change figure directly against an app's gross-gain figure for the same trail and assuming one of them is wrong — they can both be correct and still disagree by a wide margin, because they are answering different questions.
• Assuming gross gain and gross loss must be roughly equal on every hike — that holds for an out-and-back on the same trail, but not for a point-to-point route, which can legitimately climb far more than it descends or the other way around.
• Expecting a rolling trail's net change to predict how many separate climbs are actually in it — it cannot, since net change only ever looks at the start and the high point, never at what happened between them.

Where TrailCam fits in

TrailCam reports elevation gain from the gross, cumulative total — every rise your recorded track actually climbed — alongside distance, moving time and pace, and draws it as a profile underneath the map for the finished route. It is free to download.