How to read the elevation profile of a hiking route
Two 14 km routes can be three hours apart. The answer is in the elevation profile, and in the vertical axis scale that almost nobody checks.
What exactly an elevation profile is
It’s the route seen side-on. The horizontal axis is the distance covered; the vertical one, the height above sea level. Every point on the chart comes from a point on the recorded track, with its latitude, longitude and altitude. Nothing more.
There’s a detail almost nobody notices that changes what you’re looking at: the horizontal axis can be distance or it can be time. When you look back at an activity you’ve already done, many apps plot it against time, and then the climbs widen – that’s where you were slow – and the flat sections shrink. It’s useful for analysing how you did, and misleading for planning. When you’re deciding whether to do a route, always look at the profile by distance.
The rest of this guide is about learning not to trust the drawing, and to trust the numbers that come with it instead.
The key number
A typical group moves at about 4 km/h on the flat and needs an extra hour for every 500-600 m of elevation gain. A 14 km route with 900 m of D+ is about five hours of walking on the clock, plus the stops you actually make. It’s a guide, not a law: terrain, heat and the group outrank any calculation.
Trap number one: the vertical axis scale
The chart scales itself to the route’s own range. Almost every platform does this, and it’s sensible: if the axis always ran from 0 to 8,000 m, a route with 300 m of climbing would look like a flat line and tell you nothing. But it has an awkward consequence.
Picture a route that goes from 620 to 980 m. With the vertical axis running from 600 to 1,000, the climb fills the whole height of the chart and looks like a wall. With the axis from 0 to 2,000, the very same line, point for point, is a gentle hump. The route hasn’t changed: the axis labels have.
The problem multiplies when you compare. Two thumbnails of two different routes, side by side, can’t be compared with each other: each one has its own scale. The one that looks harder may have half the climbing of the one that looks flat.
The rule: look at the axis numbers first and the shape second. If the chart doesn’t label the vertical axis, the drawing is just decoration.
The three figures that actually tell you something
D+, not the highest point
SUMMIT ≠ EFFORTTotal elevation gain is every bit of climbing added together, even if you drop down in between. A route whose highest point is at 900 m can have 1,400 m of D+ if it strings together short, steep climbs. Maximum altitude only matters for cold, wind and acclimatisation; how tired you get is down to the cumulative total.
The gradient of each climb
400 M IN 2 KM = 20%It’s worked out section by section: the height gained on the climb divided by the length of that climb. Eight hundred metres spread over 14 km you walk almost without noticing; the same 800 packed into 4 km is a different route and a different day. Total D+ can’t tell the two apart: gradient can.
Where the climb falls
KM 2 ≠ KM 12Seven hundred metres of climbing at kilometre 2, on fresh legs, isn’t the same as those 700 at kilometre 12. The total is identical and the day is nothing alike. If the highest point comes 30% of the way in, you head back tired but relaxed; if it comes at 80%, you tackle the worst of it on tired legs, with less water and less daylight.
Sawtooth profiles always deceive
Five climbs of 150 m wear you out more than a single one of 750, because each one makes you start all over again and the descent in between doesn’t give you the rest it promises. On the chart they look small, almost decorative, and they add up to the same 750 m of D+ as the wall.
With one important exception: if the profile shows continuous sawteeth in an area you know is flat, that’s not terrain, it’s GPS noise. Height is the axis a receiver measures worst, and the cumulative total is a sum that never cancels out its own errors. It’s all explained in why your GPS says you climbed more than you did.
What each gradient means in practice
| Average gradient | What it’s like on foot | Example |
|---|---|---|
| Up to 5% | You barely notice it; you can chat | 100 m in 2 km |
| 5-10% | A comfortable, steady climb | 200 m in 2.5 km |
| 10-15% | You feel it in your legs and in the conversation | 300 m in 2.5 km |
| 15-20% | Short steps and stops to catch your breath | 400 m in 2 km |
| Over 25% | You don’t walk that: you climb it | 500 m in 1.8 km |
These are section averages, and an average hides the peaks: inside a section at 12% there can be a hundred metres at 25%. That’s why it’s worth looking at the shape after you’ve read the numbers, not the other way round.
What Suviard does about this
Every route in the app comes with its elevation profile, and our chart stretches the axis too: it scales to the route’s own range, for the same reason everyone else’s does. There’s no honest way to avoid it without flattening the gentle routes.
What we do is not let the drawing stand on its own. Above the profile sit the four numbers that make it readable – elevation gain, elevation loss, maximum altitude and minimum altitude – so you don’t have to guess the scale. And the profile you see comes from the track recorded by whoever did the route: we smooth it so it doesn’t jump about absurdly, but we don’t rewrite it towards what it ‘should’ be.
The route planner draws the same thing before you set off: you plot the route on the map, it snaps to real paths and the profile appears underneath. That’s the moment to check where the wall falls, before you suggest the route to a group.
The estimated time on each route page comes from the classic formula – distance divided by 5, plus elevation gain divided by 600 – and is shown next to the actual time of whoever did it. Why the estimate almost always falls short is covered in how long it really takes to climb 800 metres.
How to read a profile in thirty seconds
- 01Read the numbers on the vertical axis before the shape. How much height is there between the bottom and the top of the chart? If they’re not labelled, that drawing is no use for making decisions.
- 02Look for the D+, not the maximum altitude. It’s the number that matches how tired you’ll get. The summit only tells you what clothes to bring.
- 03Work out the longest climb: its height gain divided by its length. Above a 15% average, that section outweighs everything else on the route.
- 04Check which kilometre that climb falls at. At the start you pay with your legs; at the end you pay with water, daylight and the group’s morale.
- 05Finish with the rule of thumb: distance divided by 4 km/h, plus an hour for every 500-600 m of D+, plus the stops you’ll really make. Then compare it with the actual time of someone who’s already done it.
In short
The elevation profile is the most honest piece of data about a route and the one people read worst, because the first thing you see is a drawing whose shape depends on where the axis happens to start. The shape deceives; the axis numbers, the D+, the gradient of the climbs and the kilometre where they fall don’t.
And there’s one rule worth more than the previous five: if you can’t read a route’s profile, don’t suggest it to people you’ve talked into coming. Distance is up for negotiation with the group; elevation gain isn’t.
More on how we work with data: about Suviard.