- Telemetry is the game's own record of the car and your inputs — speed, throttle, brake, steering, gear, rpm, position and lap timing — published while you drive.
- Games send it over the network, as UDP packets to an address and port (F1 25), or through shared memory that programs on the same PC read (Assetto Corsa).
- Laid on a distance axis, two laps become directly comparable: the gap between them metre by metre, and the inputs that made it.
- Your rig does not matter to the data. A pad, a wheel clamped to a desk and a full cockpit all produce the same channels.
- StintLab reads F1 25 (both telemetry formats) and Assetto Corsa on Windows, and keeps every lap on your own PC.
What telemetry is
A racing sim works out the state of your car hundreds of times a second: its speed, its position, the load on each tyre, the gear, the engine revs, and what you are doing with the wheel and pedals. Telemetry is that state, copied out of the game so another program can use it.
Real racing teams get the same kind of picture from sensors fitted to the car and a logger in the cockpit. A sim needs neither: the numbers come from the simulation itself, reported directly by the game. What the game chooses to publish, and how often, varies from title to title — but the core is common to nearly all of them.
It carries two kinds of information:
- A continuous stream of the car's state — speed, pedals, steering, gear, rpm, position — many times a second.
- Events and timing — a lap completed, sector times, whether the lap was valid, a pit visit, a penalty.
Programs use it in two broad ways. Live tools — dashboards, overlays, external displays — show it while you drive. Analysis tools record it and show you what happened afterwards: where one lap was faster than another, and why. StintLab is the second kind. It shows nothing while you race, and everything between runs.
The channels, and what each one tells you
A channel is one quantity measured over the lap. These are the ones that matter most for driving, and what each tells you about yours:
| Channel | What it is | What it tells you |
|---|---|---|
| Speed | How fast the car is going, in km/h (or mph) | Where you are slower — and, more usefully, where the difference begins: the minimum speed in each corner and the speed at the end of each straight. |
| Throttle | The accelerator, 0 to 100%, as the game received it | How early and how smoothly you get back to full power, and where you lift. |
| Brake | The brake pedal, 0 to 100% | Where you brake, how hard, how long you stay on it and how you come off it. |
| Steering | How far the wheel is turned, left or right | How much you are working the wheel, and corrections mid-corner. StintLab records it with every lap; it does not chart it yet. |
| Gear | The gear engaged | Gear choice through slow corners, and where you change down and up. |
| RPM | Engine speed | Shift points. Recorded with every lap, not charted. |
| Lap distance | Metres from the start line | The axis everything else is laid on, so two laps line up corner by corner. |
| Lap and sector times | The game's own timing, to the millisecond | Which third of the lap the time went in, and whether the lap counted. On Assetto Corsa laps StintLab can only see pit time and penalties, so a cut may still count. |
| Position | Where the car is on the circuit | The line you drove. StintLab draws it as a map on F1 25 laps. |
Games publish plenty more — fuel, tyre wear, temperatures, the driving aids in use. Of that, StintLab keeps weather and temperatures, fuel, tyre compound, wear and pit stops on F1 25 laps, and the tyre compound and some of the driving aids on Assetto Corsa laps. And the channel you will look at most is one you make yourself, from two laps: the delta.
Why laps are compared by distance, not time
Compare two laps at the same moment — ten seconds in, say — and you are comparing two different places on the track, because the faster lap is further along. Compare them at the same distance and you are comparing the same corner. That is why telemetry tools lay laps on a distance axis, and why every chart in these guides has metres along the bottom.
Read it top to bottom and the lap explains itself. Speed plateaus on the straights and falls into a valley at each braking zone; the brake trace sits under each drop, and the throttle comes back in on the way out. The delta shows that of the 1.317 s between these laps, 1.193 s — 91% — is lost in three stretches that add up to about a sixth of the lap. Comparing two laps takes that apart corner by corner.
How games send it: UDP and shared memory
There are two common ways a game hands its telemetry to another program, and they decide how you set a tool up.
- UDP is a network message. The game sends it to an address and a port you choose, and you switch it on in the game's settings. The sender does not wait for anyone to listen, and on one port only one program gets each packet — which is why two telemetry tools on the same port get in each other's way. F1 25's settings are a one-minute job.
- Shared memory is an area of memory the game keeps up to date and other programs on the same PC can read. There is nothing to switch on, several tools can read it at once, and the reader has to run on the PC the game runs on. Assetto Corsa works this way.
Some sims can also save telemetry to a file on disk for analysis afterwards. Whichever way it arrives, the channels are much the same.
Which games StintLab reads
StintLab is sold for exactly what it reads, and nothing it might read one day. Today that is:
| Game | StintLab |
|---|---|
| F1 25 on PC — F1 25 telemetry format | Reads it. Lap and sector times, a full trace, the circuit map, weather and temperatures, fuel, tyres and pit stops. |
| F1 25 on PC — 2026 Season Pack format | Reads it. The same; its per-car lists hold 24 cars instead of 22. Lap, participant and car telemetry packets are size-checked against the layout; not yet confirmed against a real 2026 session on a racing PC. |
| Assetto Corsa on PC | Reads it. Lap and sector times, a full trace, the track layout, the car, tyre compound and some of the driving aids. No map, weather, fuel or tyre wear. |
| Assetto Corsa Competizione | Not supported yet. It publishes the blocks StintLab reads, but it has not been checked against the real game, so it is not on the supported list. |
| F1 24 and earlier F1 games | No. Each F1 game has its own packet layout; this edition reads F1 25's. |
| iRacing, Le Mans Ultimate, Automobilista 2, rFactor 2, RaceRoom, Assetto Corsa EVO | No. Not read by this edition. |
| Console versions (PlayStation, Xbox) | Not supported. F1 25 on a console can send its telemetry across your network, but StintLab has not been tested that way. |
What to look at first
A first telemetry session can be a wall of lines. Read it in this order, and it turns into a short list of things to practise:
- The delta. Where does it climb? Those stretches are where the time went. Ignore everything else for now. How to compare two laps.
- The brake trace at those stretches. Does the faster lap brake later, harder, or for less time? Or at the same point, like both laps above? Braking points.
- The bottom of the speed valley. The minimum speed through the corner is the most telling single number in a lap: a few km/h there are paid for all the way to the next braking zone, or until both cars reach top speed.
- The throttle on the way out. Who is back to full power first, and how smoothly? A late or hesitant pick-up shows as a gap that keeps growing down the straight.
That order works in any car and any game. For the whole method — from a baseline to a practice plan and back — see how to get faster at sim racing.
Your rig does not matter — to the data
The game reports the inputs it received, after your wheel software's calibration and the game's own controller settings. So a controller on the sofa, a wheel clamped to a desk and a direct-drive base in an aluminium cockpit all produce the same channels. StintLab never talks to your hardware — no drivers, no plug-ins, no device list. If the game works with your wheel, StintLab works with it.
That makes telemetry a fair test of the rig itself. Pedal calibration shows up in the throttle and brake traces, and whether an upgrade made you faster shows up in your consistency over weeks — both covered in your sim rig, measured. On a pad, the traces look different again: see faster on a controller.
And because StintLab draws nothing over the game — no overlay, no pop-ups — there is nothing to set up for VR or triple screens. The only sign it is running is its icon in the Windows tray.
Where your telemetry goes
With StintLab, nowhere. Each lap is written to your own disk as a plain JSON file the moment the game times it, and the pages it builds from them are self-contained HTML files that open in any browser. There is no account, no upload and no licence server; the app makes no outbound connection at all. The one thing it listens to is the game.
Sharing is by choice: send a teammate a lap file and they can import it as a target for their own laps. It never counts as their driving.
Start recording in five minutes
- Install StintLab on the PC you race on.Windows 10 or 11, 64-bit. Setup installs it to your own user folder and fetches Microsoft's WebView2 runtime if your PC lacks it.
- Switch telemetry on in the game.F1 25: Settings → Telemetry Settings — UDP Telemetry On, UDP Broadcast Mode Off, IP address 127.0.0.1, port 20777, UDP Format F1 25 or 2026 Season Pack. Assetto Corsa needs nothing switched on.
- Drive.StintLab records in the background whenever the game is sending. There is nothing to start or stop, and each lap is saved the moment the game times it.
- Open your laps.View → My laps. Tick two laps to overlay them on one distance axis, or one to see it on its own with every braking zone.
- If nothing appears, open Setup check.Help → Setup check lists StintLab, your laps folder, F1 and Assetto Corsa, says which one needs attention and what to change.
That is all of it. Everything in these guides — the overlays, the braking table, the theoretical best, the practice plan, the season record — is built from the laps it records from then on.
Questions
What is telemetry in sim racing?
The game's own record of what the car and the driver are doing — speed, throttle, brake, steering, gear, engine speed, position and lap timing — published many times a second while you drive, so other programs can record, display or analyse it.
Do I need a wheel and pedals to use telemetry?
No. The game reports the inputs it receives, whatever they come from, so a controller produces the same channels as a direct-drive wheel. What changes is the shape of your traces, not whether you have them.
Is sim racing telemetry the same as real F1 telemetry?
The idea is the same and many channels overlap — speed, throttle, brake, gear, rpm, lap distance. A real car logs its data from sensors fitted to it, and carries far more channels than a game publishes. In a sim, the numbers come from the simulation itself.
Can I use telemetry while I drive?
Live dashboards and overlays do that. StintLab is the other kind of telemetry tool: it records every lap and shows you the analysis between runs. It draws nothing over the game while you drive.
Which games does StintLab read?
F1 25 on PC, in both its telemetry formats (F1 25 and the 2026 Season Pack), and Assetto Corsa on PC. Assetto Corsa Competizione is not on the supported list yet, console versions are untested and not supported, and other sims and older F1 games are not read.
Is using telemetry cheating?
Reading your own laps after a session is how drivers learn, in sims and in real racing. Online leagues set their own rules about tools, so check yours; StintLab only reads what the game itself publishes, never changes the game, and shows nothing on screen while you race.
Can I see other drivers' telemetry?
StintLab records your own car and nothing else. The only other laps it holds are lap files someone chose to send you, imported by hand as a reference.
Does it work on a Mac or on a console?
Not on a Mac: StintLab is a 64-bit Windows app for Windows 10 and 11. Console versions are not supported — F1 25 on a console can send its telemetry across your network, but StintLab has not been tested that way. The pages it builds from your laps open in any browser, on any machine.