Reference
Trip stats explained: moving time, average speed, elevation gain
Short answer
The two numbers people misread most often are average speed and elevation gain. Average speed is distance divided by moving time, not total time, so it describes how fast you went while you were going somewhere rather than being diluted by every red light. Elevation gain is the sum of all the climbing you did, not the difference in altitude between the start and the end — a loop back to your own front door can still have several hundred metres of gain.
Everything else follows from those two ideas: that time has to be split into moving and stopped before it means anything, and that a total is not the same as a net change.
These are the definitions used inside Speedometer One, with the thresholds that actually decide each number. Other apps compute some of these differently — that is the whole reason two apps recording the same drive can disagree — so where a specific value matters, it is stated.
Time
Total duration
The whole span from the first recorded point to the last. It includes everything: traffic, the fuel stop, the argument about which exit to take.
Moving time
Only the intervals where the vehicle was actually in motion. Two filters decide it. Speed has to be above a small threshold — 0.5 m/s, about 1.8 km/h — which keeps GPS jitter at a standstill from being counted as creeping forward. And the gap between two recorded points has to be plausible: an interval longer than five minutes is not counted at all, because it means the recording was interrupted and nobody knows what happened in between.
Stopped time
Total duration minus moving time. On a motorway run it is close to zero. On a city commute it is routinely a quarter of the trip, and seeing that number is often more informative than seeing the average speed it explains.
Speed and distance
Distance
Accumulated segment by segment between consecutive recorded points, and only while the fix is good enough to trust — better than 50 metres of reported accuracy. Below that standard the app stops adding metres rather than adding wrong ones, which is why distance can appear to stall under heavy tree cover or in a multi-storey car park.
There is a second guard for the tunnel case. When a receiver reacquires after a blackout, the first fix can be a long way from the last one, and counting that jump would add kilometres you never drove. Any movement implying more than 100 m/s over the elapsed time is rejected: come out of a tunnel after ten seconds without signal and anything beyond one kilometre is discarded rather than credited.
Average speed
Distance divided by moving time. This is the definition that answers "how fast was I going", which is almost always the question being asked.
Dividing by total time answers a different one — "how quickly did I complete this journey" — and gives a much lower figure on any trip with stops. Both are available: the trip screen shows total duration and moving time next to each other, so either can be worked out.
Maximum speed
The highest single reading of the trip, but only recorded while accuracy was better than 30 metres — a stricter bar than for distance. A top speed is a single sample rather than an average, so one bad fix can invent a record that never happened, and a record that never happened is worse than no record.
Average pace
The same information as average speed, turned inside out: time per unit of distance instead of distance per unit of time. Minutes per kilometre rather than kilometres per hour. It is the natural unit for anyone who runs or cycles, where "four thirty a kilometre" is more legible than "13.3 km/h".
Altitude
Altitude, and which sea level it means
A raw GPS fix gives height above the WGS84 ellipsoid: a smooth mathematical model of the Earth, chosen for the convenience of the mathematics rather than for its resemblance to the ground. It can sit tens of metres away from real sea level where you happen to be standing.
What a map means by altitude is height above the geoid — the surface an undisturbed global ocean would settle into, which follows the Earth's actual gravity field and is anything but smooth. The difference between the two is the geoid separation, and it ranges from roughly −105 to +85 metres worldwide.
GPS receivers already know this value and publish it in their NMEA output. Speedometer One reads it and subtracts it, so displayed altitude is height above mean sea level. Until that value has arrived the app says it is calibrating, rather than showing a number it knows to be offset.
Elevation gain
The sum of every upward step across the whole trip. Not the difference between the start and the end.
The distinction is the entire point of the metric. Drive a loop through hills and return home: your net altitude change is zero, and your elevation gain might be six hundred metres. One of those numbers describes the drive.
Only rises larger than 1.5 metres are counted. Without a threshold, ordinary GPS altitude noise on a flat road would accumulate into a mountain range over an hour.
Altitude range
Highest point minus lowest point. It says how much vertical the trip covered, and nothing about how many times you went up and down. Read it next to elevation gain: a range of 200 m with 200 m of gain is one climb, while a range of 200 m with 900 m of gain is a rollercoaster.
Shape of the drive
Splits
The trip cut into equal distance segments — one kilometre, one mile or one nautical mile, following whichever units you have set — each with its own average speed, duration and altitude change. The last one is usually a partial and is labelled with its real length rather than being rounded up.
Splits are where a drive stops being a single number and becomes a story: the slow first kilometre out of town, the fast middle, the climb you felt at the time and can now see.
Speed zones
The share of your time spent inside each band of speed. It captures the character of a trip in a way averages cannot — the same 60 km/h average can be a steady rural cruise or a stop-start crawl punctuated by short bursts, and the zones tell those apart immediately.
Driving smoothness
A score out of 100, built from the trip's hard braking and hard acceleration events. It is the one metric here that is about how you drove rather than what you drove.
An event is registered from the accelerometer, not from GPS. Braking counts as hard beyond 0.4 g, acceleration beyond 0.3 g, and in both cases the force has to be sustained for at least half a second — a pothole is a spike, not a manoeuvre.
The score starts at 100. Each event costs points in proportion to how hard it was, and the total is scaled to a rate per 100 km so that a long calm motorway drive is not flattered by its own length. Short trips are measured against a five-kilometre floor, so a single sharp stop on a two-kilometre errand does not wreck the score.
| Score | Reads as |
|---|---|
| 90–100 | Smooth |
| 75–89 | Good |
| 50–74 | Normal |
| Below 50 | Aggressive |
Treat it as a comparison against yourself. The same commute, driven twice, is a fair test; your score against someone else's on different roads is not.
Which numbers are actually worth watching
Most of these are interesting once. Three of them repay attention over time.
- Stopped time as a share of the trip. The clearest measure of whether a route or a departure time is working. It moves when you change something real.
- Average speed on a repeated journey. Your commute, driven the same way, is a controlled experiment. Compare it with itself and the number means something.
- Smoothness on that same journey. The one metric here you can directly improve, and the one that shows up in fuel consumption and brake wear.
Top speed, by contrast, is the number everyone looks at first and the one that tells you least. It is a single sample from a single second of a long drive.
Common questions
What is the difference between moving time and total time?
Total time is the whole span including stops; moving time counts only the intervals where you were actually going somewhere. The difference between them is stopped time.
Why is my average speed higher than distance divided by total time?
Because it is calculated over moving time. Dividing by total time is a valid figure but it answers "how long did the journey take", not "how fast was I going".
What does elevation gain mean on a trip?
The total of all the climbing, not the net change between start and end. A round trip has zero net change and can still have a large gain. Rises under 1.5 m are ignored as noise.
Why is GPS altitude less accurate than GPS position?
Satellite geometry. They are spread above you and never below you, so the vertical is constrained from one side only. Altitude error typically runs two to three times the horizontal error on the same fix.
What is a good driving smoothness score?
90 and above reads as Smooth, 75 to 89 Good, 50 to 74 Normal, below 50 Aggressive. It is most meaningful compared with your own earlier drives on the same roads.
See these on your own drives
Speedometer One records every trip and works all of this out for you — route, splits, times, climb and smoothness. Free on Android.
Disclosure: I am the developer of Speedometer One, the Android app this site is about. The thresholds quoted here — 0.5 m/s for movement, 50 m and 30 m accuracy limits, 1.5 m for elevation, 0.4 g and 0.3 g for driving events — are the values used in the app's own source, not industry standards. Other trip recorders make different choices, which is exactly why two apps can disagree about the same drive.