The undercut and the overcut

The undercut and the overcut are the two ways to pass a rival in the pits rather than on the track. Both depend on one driver stopping before the other.

• The undercut: the driver behind pits first, uses their fresh tyres to set fast laps, and is ahead when the other driver makes their stop.
• The overcut: the driver behind stays out longer, sets fast laps while the other driver is on their new tyres, and comes out ahead after their own later stop.

#How the undercut works

Say Driver A leads Driver B by 1.5 seconds and both need to make one stop.

1. B pits first and comes out on new tyres.
2. On their out lap and the lap after, B's new tyres are a second or two a lap quicker than A's worn ones.
3. A pits one lap later. By then B has made up more than the 1.5 seconds.
4. When A comes out of the pits, B is already past, and is now in front.

The key is the difference in pace between old and new tyres. When tyres degrade quickly, that difference is large and the undercut is powerful. At some tracks, an undercut can be worth two or three seconds.

The driver being undercut has a simple defence in theory: pit on the same lap, or the lap straight after, so the other driver doesn't get several laps on fresher tyres. This is called covering the stop. The catch is that the leader often doesn't know the car behind is pitting until it's already in the pit lane.

#How the overcut works

The overcut works the other way around. It relies on the new tyres being slow to start with, while the old tyres still have some life in them.

That can happen when:

• the new tyres are hard to warm up, so the out lap is slow (common with the hard compound, or on a cold track),
• the driver who stopped first comes out into traffic and gets held up, or
• the driver staying out has clear track and can push hard on tyres that are worn but not finished.

In those cases, the driver who stays out gains time while the other is struggling, and can come out ahead after their own stop. The overcut is most often seen at tracks where tyre wear is low, such as Monaco, or in cool conditions.

#Out laps and in laps

Two laps matter most in a pit battle:

• The in lap is the lap a driver completes before pitting. They want to push as hard as possible on their old tyres.
• The out lap is the first lap after the stop. They want to get their new tyres up to temperature quickly without overdoing it.

When people compare whether an undercut worked, they're usually comparing one driver's out lap with the other's in lap.

#Why traffic matters

A driver who pits first has to come out somewhere. If they rejoin behind slower cars still on their first stint, they can lose all the advantage of their new tyres. Teams look for a gap before calling a driver in. That's why you'll hear engineers talking about "the gap to the car behind" when they're deciding whether to stop.

#When neither works

Sometimes both drivers pit on the same lap. Then the stop itself decides it: the faster pit crew wins. A slow stop of even a second can lose a position, and a problem like a sticking wheel nut can cost much more.

#The undercut under the 2026 rules

The basic idea hasn't changed, but the 2026 cars add another factor. They use a lot of electrical energy, and how much a driver has available on a given lap affects how fast that lap is. A driver on their in lap or out lap may use more battery than usual to gain time, which then has to be recharged later. Teams now plan energy use around the pit stops as well as tyres. See tyre and energy management for more.