There’s a specific kind of pit stop that looks “fine” on TV and still breaks your race.
It’s not the 6.3s wheel-gun nightmare. It’s not the unsafe release. It’s the stop that happens at the wrong time — the one that drops you into a DRS train you can’t escape, or the one that comes a lap too late and turns an undercut threat into an undercut reality. The pit stop itself is a constant. The window is the variable. And in modern Formula 1, the window is where races quietly get won, lost, and occasionally misread by everyone (including the team that called it).
In this post, we’ll break down the F1 pit stop window with actual numbers — pit lane time loss, tyre delta, and traffic cost — then show why even smart teams still miss it, especially on weekends where “too early” and “too late” are separated by one messy out-lap.
What a pit stop window actually is (and what it isn’t)
A pit stop window is often described like it’s a neat rectangle on a strategy sheet: lap 14 to lap 20, boxed, done. But that’s the simplified version — the one that assumes your pace is stable, traffic is predictable, and tyre behaviour is polite.
In reality, there are two different “windows” running at once:
- The tyre window (hard window): the range of laps where you can pit without failing to reach the end (or the next stop) on tyre life.
- The position window (effective window): the range of laps where you should pit if you want to gain/defend track position once the stop cycles through.
When fans talk about an undercut, they’re talking about the second one. When engineers argue on the pit wall, they’re usually arguing because these two windows don’t overlap as cleanly as the spreadsheet hoped — especially in traffic-heavy races where clean air is a performance upgrade you can’t bolt onto the car.
If you want the clean-air side of this in full detail, it pairs perfectly with our earlier breakdown: Clean Air Is King: How Dirty Air Changes Strategy.
The three numbers that build every window
Strategy teams can dress it up in different language — “target lap,” “cover,” “offset,” “degradation phase,” “plan A/B/C” — but almost every pit window decision is built on three inputs:
- Pit lane time loss (pit delta)
- Tyre delta (fresh vs used pace, including warm-up)
- Traffic loss (what happens if you rejoin into someone else’s race)
1) Pit lane time loss: the track sets the entry fee
The first truth of windows is brutally simple: some circuits charge more for a pit stop.
Here’s the green-flag pit stop time loss (door-to-door, including a typical stationary time) at a few 2025 reference tracks:
| Circuit | Pit stop time loss |
|---|---|
| Monaco | 19.4s |
| Baku | 19.7s |
| Silverstone | 19.9s |
| Barcelona | 22.2s |
| Singapore | 29.1s |
That last number is why Singapore strategy always feels like a slow-burn thriller. A 29-second pit loss doesn’t just delay your stop — it changes the entire undercut economy. The “price” of switching tyres is so high that teams become allergic to pitting into anything except guaranteed clean air or a discounted neutralisation.
2) Tyre delta: the advantage isn’t a number, it’s a curve
Tyre delta gets discussed like it’s one value (“new Mediums are 0.9s faster”), but the real delta is a curve that changes every lap.
A fresh tyre usually gives you:
- Out-lap bite (if the compound warms quickly and the traffic allows you to use it)
- A short phase of peak grip (often 2–6 laps depending on compound and track)
- A degradation slope (the rate at which the tyre starts giving the time back)
That’s why “pitting early for the undercut” can be a trap. If you stop at the first moment you can, you’re also volunteering to run the longest possible stint on your next tyres — which means you’ll be the one defending with fading rubber later. If you’ve ever wondered why some drivers undercut successfully and still look vulnerable 15 laps later, this is the reason.
If you want the mechanics behind that slope — the part where lap time quietly starts telling the truth — our primer is here: Tyre Degradation 101 (For People Who Actually Want to Understand It).
3) Traffic loss: the hidden tax that ruins “perfect” calls
Traffic loss is the part fans underestimate because it’s not a fixed penalty — it’s situational, and it compounds.
Rejoin behind a car that’s 0.7s slower and you can’t pass, and the cost isn’t just one lap. It’s every lap until the next pit phase or a Safety Car changes the game. Add dirty air, tyre overheating, and battery deployment compromises, and your beautiful undercut attempt turns into an expensive tyre-life donation.
This is why teams often wait until they can “pit to clear” — not because they forgot the undercut exists, but because they’ve learned that a theoretical 1.2s out-lap gain is worthless if it buys you five laps staring at a rear wing.
The window equation (the one teams are actually solving)
You can explain a pit window with one inequality:
Pit now if the time you gain from tyre offset (minus traffic and warm-up penalties) is greater than the time you risk losing by staying out while your rival pits (the undercut threat).
A practical way to think about it in race terms:
- Let G be your current gap to the car you’re fighting.
- Let Δ₁ be the undercut gain your rival gets on their out-lap (fresh tyre vs your old tyre).
- Let Δ₂ be the gain on the following lap if you’re still out.
- Let T be the traffic penalty they pay after rejoining (if any).
If your rival pits and you stay out, they jump you if:
Δ₁ + Δ₂ + … − T > G
That’s the undercut window, in plain language. And the reason it feels so “knife-edge” is because Δ₁ can swing wildly based on warm-up and clear air. On a track with strong warm-up and high degradation, the first lap on new tyres can be worth an entire overtaking move. On a track where tyres take a lap to wake up — or where pit exit drops you into traffic — the undercut can be dead on arrival.
Now zoom out and include the tyre-life consequence (the “too early” cost): even if you win the undercut battle today, you still have to survive the tyre war tomorrow — the final stint — without bleeding the position back.
When “too early” becomes “too late” (the two classic failure modes)
The pit stop window closes in two different ways, and they feel completely different from inside the car.
“Too early” fails because you spend tyres to buy nothing
Pitting too early usually looks aggressive. In reality, it often means one of three things happened:
- You rejoined into traffic, so the tyre delta never converted into lap time.
- You extended the next stint too far, so your late-race pace collapsed relative to cars that stopped later.
- You opened yourself to a cheap stop for others (VSC/SC timing), because you committed before the race’s probability spikes hit.
This is why street circuits with high pit loss (hello, Singapore) punish “instinct” calls. When the pit lane costs 29.1s just to change tyres, you can’t afford to discover you’ve bought the wrong kind of track position.
“Too late” fails because the undercut isn’t waiting for your permission
Pitting too late is the quieter failure — the one that happens while a driver is saying “my tyres are still OK.”
Because “OK” isn’t the metric. The metric is whether your rival can do a faster out-lap than you can do on old tyres, and whether they can do it without being trapped.
The most painful version is when a driver stays out to avoid traffic… and the traffic clears one lap after their rival pits. That’s the moment the window flips. One lap earlier, the undercut would have failed. One lap later, it works. And that’s why teams sometimes miss by a lap even when the model is right — because the model can’t perfectly predict the one car that will become the moving roadblock.
Circuit personality: why the same strategy logic gives different answers
Pit windows don’t just depend on your car. They depend on what the circuit allows the strategy to be.
Monaco: a window that exists, but rarely converts into overtakes
Monaco’s pit loss is relatively low at 19.4s, but the track’s overtaking limitation means the “effective window” is often less about lap time and more about not losing track position. In 2025, even forcing extra stops couldn’t magically create an undercut economy if the pass itself is nearly impossible without a major offset.
The window exists. It’s just narrow, and it’s often strategic theatre: teams pitting to satisfy constraints, cover rivals, or dodge bad timing — not because the out-lap is going to manufacture a pass.
Barcelona: the classic tyre-deg window
Barcelona’s pit loss sits higher at 22.2s, but the circuit tends to reward tyre management and sustained pace — which makes the undercut/overcut battle feel more “pure.” If your car warms tyres well, an undercut can be lethal; if it doesn’t, you can sometimes overcut by staying in clean air and banking lap time while the rival warms up.
Baku: low pit loss, high consequence
Baku’s pit loss is 19.7s, which is deceptively inviting — but it’s also a track where traffic and Safety Car probability can turn windows into traps. The best Baku stops are often the ones that combine three things at once: a clean rejoin, a compound that switches on quickly enough to attack, and a plan for battery deployment that doesn’t waste the tyre offset before the braking zone.
Singapore: when the pit lane is expensive, timing becomes everything
At 29.1s pit loss, Singapore is the definition of “pit once, and be sure.” Windows here are less about theoretical delta and more about operational certainty: can you clear traffic, can you protect tyre temperatures, can you avoid being the one who pits right before a neutralisation.
On these tracks, teams miss windows not because they can’t do maths — but because the maths is being done on a moving target.
Why 2025 made pit windows feel sharper (and more costly)
The 2025 season delivered a perfect reminder that strategy mistakes don’t need to be huge to matter — they only need to be irreversible.
Lando Norris won the 2025 Drivers’ Championship with 423 points, just two points ahead of Max Verstappen on 421, with Oscar Piastri third on 410. McLaren topped the Teams’ standings on 833 points, ahead of Mercedes (469) and Red Bull (451). When margins are that tight, “we lost 1.8s in traffic after the stop” isn’t trivia — it’s season-shaping.
And crucially: there’s no fastest lap bonus point from 2025 onwards, which removed one of the sport’s weird late-race incentives (the free-stop lottery and the ‘steal the point’ games). That change didn’t reduce the importance of windows — it increased it. If you can’t buy a point with a late pit for fastest lap, you have to earn points the hard way: by finishing positions, which means pit timing that protects track position instead of gambling for a bonus.
If you want to run your own “how costly was that one position?” scenarios across a full year, our points tool is built for it: RaceMate Championship Simulator.
The takeaway: the window isn’t a lap number — it’s a prediction under pressure
A pit stop window is not a time slot you discover. It’s a forecast you choose to believe.
You’re predicting tyre warm-up. You’re predicting degradation. You’re predicting traffic behaviour, and whether that midfield battle will still exist when you rejoin. You’re predicting whether a VSC shows up at the exact moment it always seems to show up — right after you’ve committed.
When teams “miss the window,” it’s rarely because they forgot the basics. It’s because the effective window is built from variables that change faster than a strategist can confidently admit. That’s why the best calls often look boring in the moment: they don’t chase theoretical lap time, they chase clean air, conversion, and control.
Because in Formula 1, “too early” isn’t an error. It’s paying for performance you never get to use. And “too late” isn’t hesitation. It’s letting someone else spend their tyres at the perfect moment — and using your old ones as the reference they beat.