To measure your ski speed, put your phone in a zipped inside chest pocket, start a GPS speedometer app at the top of the run and stop it at the bottom. Then check the max speed. The phone doesn’t need to see the slope, because GPS reaches it through your jacket. Expect the figure to be slightly under your true peak, especially on steep pitches, for reasons that are easy to understand once you know them.
Here’s the method, why phone numbers run a little low, and how to keep your battery alive in the cold.
How to track your speed on a ski run #
- Before you get on the lift, open Speedometer GPS, allow location access and wait for the GPS pill under the number to read GOOD or EXCELLENT. Pick km/h or mph with the unit button.
- Leave keep-screen-on enabled. It’s on by default. The app only tracks while it’s open on screen, with no background tracking, so it has to stay awake in your pocket.
- At the top, step clear of the lift, tap Reset (it asks you to confirm), then Start. Put the phone in an inside chest pocket and zip it.
- At the bottom, stop somewhere out of the way, tap Stop and read your max speed. Tap Save to keep the run as its own trip.
- Repeat for each run.
Stopping at the bottom matters. If you leave the app running up the chairlift, the lift ride gets added to your distance and time and drags your average speed down. Your top speed won’t change, since lifts are slower than skiing, but the rest of the numbers stop meaning much.
If a pocket tap presses Stop, the trip just pauses. Reset always asks before it clears anything. Touchscreen gloves help, or take a glove off at the lift station rather than on the slope.
Why your top speed reads a little low #
Phone GPS is good at measuring sustained speed. It’s less good at catching a short peak, and there are three reasons.
The reading is smoothed #
The app shows the average of the last five one-second readings and takes max speed from that smoothed value. That stops a single glitchy reading from creating a fake top speed you’d brag about all season. The trade-off is that a peak you hold for only a second or two reads a bit under, while a speed you hold for five seconds or more reads close to true.
Steep slopes hide part of your speed #
Most phone GPS chips report speed over the ground in the horizontal plane. On a steep pitch you’re also moving downward, so your true speed along the slope is higher than the horizontal figure:
| Slope angle | Grade | True speed is higher than GPS by |
|---|---|---|
| 10° | 18% | 1.5% |
| 15° | 27% | 3.5% |
| 20° | 36% | 6.4% |
| 25° | 47% | 10.3% |
| 30° | 58% | 15.5% |
On gentle groomers it makes no practical difference. On the steepest part of a run, which is often where you hit your fastest speed, it can shave a few km/h off the reading.
The signal can be weaker #
Tree-lined runs, narrow gullies and a phone buried under layers all weaken the fix. The GPS pill shows how good it is, and fixes worse than 20 m aren’t used for speed. If the signal drops out for five seconds, the reading goes to 0 and the pill shows SEARCHING instead of freezing on an old number. We go into lag and smoothing in GPS speed lag and trip distance errors.
So treat a phone’s max speed as your sustained top speed, not a radar-gun peak. It also explains why two friends with different apps on the same run rarely get the same number.
Reading your run afterwards #
Each saved run keeps its distance, top speed, average speed while moving, total time and moving time. Open it and you get a speed chart showing where you were fastest, and the route: drawn on Apple Maps on iPhone, or as a sketch from your recorded points on Android. You can export the track as a GPX file to open in other mapping tools. The app keeps up to 100 trips on your phone, and the Trips screen adds them up into lifetime totals.
A note on distance. To stop GPS drift adding phantom distance, the app ignores movement under 5 m between one-second fixes. On a downhill run you’re above that threshold, which is about 18 km/h (11 mph), almost all the time, so it doesn’t matter. But it does mean the app under-counts distance on slow sections, in cross-country skiing and on snowshoes. Speed readings aren’t affected.
Altitude and vertical drop #
Under the speed readout, the app shows your altitude in metres or feet and your compass heading while you’re moving. Note the altitude at the top and the bottom and you have a rough vertical drop for the run.
GPS altitude is less precise than GPS position, so treat it as approximate. For an exact figure, the resort’s trail map usually lists each lift’s vertical. We cover how altitude affects GPS readings in GPS altitude effects on speed and distance.
Keeping your phone alive in the cold #
Cold is the real enemy on the mountain. Apple designs iPhones for ambient temperatures between 0 and 35 °C (32 to 95 °F). In colder conditions battery life shortens temporarily and the phone may shut itself down, then recovers once it warms up.
- Keep it close to your body. An inside chest pocket is much warmer than a pants pocket or a backpack.
- Carry a small power bank in another inside pocket, since GPS plus a lit screen uses real power.
- Don’t worry about signal. GPS works without cell coverage, so the app works on remote lifts and in airplane mode. Only the ads need a connection.
More on managing power in our battery saving tips for long trips.
Speed and safety on the slopes #
Tracking speed is for curiosity and for seeing yourself improve, not for racing the crowd. Resorts mark slow zones near lifts, lodges and beginner areas, and patrollers can take passes for reckless skiing. Skier responsibility codes give the people below you the right of way, and they can’t see you coming.
Never look at the phone while you’re moving. Check it at the bottom. If you’d like a warning when you pass a set speed, turn on the speed limit alarm in Settings before you go up. Over the limit, the phone buzzes and beeps and repeats every ten seconds until you slow down, which you may feel through your jacket.
The same method works for snowboarding, sledding and tubing.
Frequently asked questions #
Can my phone track my skiing speed accurately? #
For sustained speed on open runs, yes, typically within a small margin with a good fix. It reads a little under your true peak on short bursts and steep pitches, because the reading is averaged over five seconds and phones report horizontal speed.
Why does my ski app show a different top speed than my friend’s? #
Apps smooth readings differently, phones receive satellites differently, and a phone deep in a pack gets a weaker fix than one in a chest pocket. An app that records single-second spikes will usually show a higher “top speed” than one that averages them out.
Does GPS work inside a ski jacket? #
Yes. GPS signals pass through fabric and insulation. An inside chest pocket is a good spot because it keeps the phone warm and near the top of your body, with open sky above.
Will the cold drain my phone battery? #
It can, quickly. Apple designs iPhones for 0 to 35 °C (32 to 95 °F) ambient temperatures, and cold temporarily cuts battery life. Keep the phone in an inside pocket, and carry a power bank on long days.
Do I need cell service to track ski speed? #
No. GPS comes from satellites, so a GPS speedometer works on the mountain with no signal at all. You only need data for things like loading maps in other apps.