Fixing a slice: what the launch monitor says about your slice and how to read it

The ball starts more or less straight, then bends right and lands two fairways over. The slice, for right-handers, and the same mirrored for left-handers. Every golfer has a tip for it: stronger grip, close the stance, keep the arms connected. Some help, most do not, and the reason is that nobody knows what exactly happens at impact. The launch monitor knows. It shows it in two numbers.

The two numbers

Face angle is the direction the face points at impact, relative to the target line. Club path is the direction the club head is moving at impact, also relative to the target line. The difference between the two is called face to path: face angle minus club path. A positive value means the face points to the right of the path, so open (TrackMan, Face-to-Path).

The physics behind it has not been a matter of opinion since launch monitors started measuring: with a centred strike the ball starts mostly where the face points, and it curves away from the swing path towards the face. If the face points right of the path, the ball curves right. That is the slice. Not the path alone, not the face alone, but the difference.

How big the curve is

TrackMan gives an example: a PGA Tour driver with a face to path of minus two degrees curves about 19 yards left over 275 yards, a good 17 metres. Two degrees. That is the distance between a fairway and the rough beside it. An amateur slice with six or eight degrees of face to path therefore lands not just off line but on the neighbouring hole. And because the face is open, the ball has more loft, more spin and less ball speed: the slice costs not only direction but distance.

Nine ball flights, two numbers

Start direction and curve place every shot in exactly one pattern, and every pattern says which of the two numbers is wrong. Read for right-handers, mirrored for left-handers:

Start	Curving left	Straight	Curving right
left of target	Pull hook: face left, path further right of it	Pull: face and path both left, by the same amount	Pull slice: face left, path further left still
at the target	Draw: face at the target, path right of it	Straight: face and path both at the target	Slice: face at the target, path left of it
right of target	Push draw: face right, path further right	Push: face and path both right, by the same amount	Push slice: face right, path left of it

The table is the whole ball flight in one rule: the face says where it starts, the path relative to the face says where it curves. Hit three balls, watch where they start and which way they bend, and you know without any number which row and which column you are in. The screen then confirms it in degrees. All nine with example values are in Draw, fade, hook and slice.

The three patterns

On the screen a slice almost always looks like one of three patterns:

• Path left, face near the target. Club path minus 6, face angle 0, face to path plus 6. The ball starts at the target and curves right. The classic over-the-top slice; the path is the problem.
• Path at the target, face open. Club path 0, face angle plus 5, face to path plus 5. The ball starts right and curves further right. The push slice; here the face is the problem, often the grip.
• Both. Path left, face right. The ball starts right and curves hard. Usually an attempt to "hold" the slice that pulled the path even further left.

The same three slices look identical from the outside. The tip that helps the first makes the second worse. That is why most tips fail: they treat a pattern the player does not have.

The order that works

The face first. The face decides where the ball starts, and it is the number that changes fastest: through the grip and the position of the hands. A professional sees in ten seconds from the grip whether the face returns open at impact. Goal for the first session: face angle near zero on average.

Then the path. If the face is at the target and the ball still curves, it is the path. It hangs on the body turn and on whether the club comes from above or from the inside. That is the longer work; it takes more than an hour, and here the professional pays off.

Then keep face to path. The goal is not zero on both but zero in the difference. Many good players have a path of plus two and a face of plus one: a slight draw, on purpose. What counts is that the two fit together.

Four drills and the number that has to move

A drill without a target number is a pastime. Each one therefore comes with the column you check to see whether it worked:

Drill	What you change	Which number reacts
Stronger grip	Both hands an eighth of a turn to the right, ten balls	Face angle moves towards zero
Half swing, 7-iron	Back to hip height only, slowly	Face angle settles, the spread drops
Gate of two sticks	The club has to pass between the sticks	Club path moves right, away from minus
Ball further back in the stance	Half a ball width towards the back foot	Club path turns more positive, attack angle steeper

Ten balls before the change, ten after, and always the middle value. If the number does not move, that was not your cause, and you go to the next drill. That is the real advantage over the range: you notice in ten minutes that a tip does nothing for you, instead of believing it for a summer.

Why the simulator is the right place for it

On the range you watch the ball fly and guess. In the simulator you see the two numbers after every shot and know what you changed. Ten balls with a stronger grip, and the face-angle column tells you whether it worked before you get used to the ball flight. The precondition is a system that delivers club data: TrackMan does, as do Foresight with club markers and Uneekor; not every entry-level device shows face angle and club path. How the systems measure is in Radar or camera, what the other numbers mean in Understanding launch-monitor numbers.

More on this: How to hold the golf grip and Driver tee shot for beginners.

Four evenings, one winter

A slice does not disappear in an hour, but it does in four, if they come in order.

1. Measure. Twenty balls with the 7-iron, changing nothing. Write down face angle, club path and the difference as averages. Now you know which row of the table you are in.
2. The face. Grip and half swings until the face angle averages close to zero. For many people the slice is half gone at this point.
3. The path. The gate of two sticks, plus an hour with a professional, because the path hangs on the body and not on the hands.
4. The round. Eighteen holes on the screen, with the driver, under pressure. What works on the mat after three evenings has to survive a tee shot.

The distance comes back along the way. An open face gives the ball more loft, more spin and less ball speed, so a slice costs twice, in direction and in metres. Bring the difference from six degrees to two and you see it in the carry column before you see it on a course.

81 of the 110 venues in Switzerland offer coaching. Whoever wants to lose their slice in one winter books an hour with a professional and three hours alone, with the screen. The venues are on the training page.

Frequently asked questions

What causes a slice?

A face that is open to the swing path at impact: face to path greater than zero. The ball starts where the face points and curves away from the path towards the face, to the right for right-handers.

How much curve does one degree of face to path make?

TrackMan cites about 19 yards of curve at minus two degrees over 275 yards for a tour driver, so a good eight metres per degree. An amateur slice of six degrees lands correspondingly far from the fairway.

What should I fix first, face or path?

The face. It decides where the ball starts and changes fastest through the grip. Only when the face is at the target and the ball still curves is it the path's turn.

How do I tell whether the face or the path is at fault?

By the start direction. If the ball starts at the target and then curves right, the path is left of the face, and the path is the subject. If it starts right already, the face is open to the target, and the grip is the quickest lever. If it starts left and bends hard right, both are involved.

How long does it take to get rid of a slice?

With numbers, four evenings: one to measure, one for the face, one for the path, one for a round under pressure. Without numbers it takes longer, because every tip treats a pattern you may not even have.

Sources

• TrackMan: What is Face-to-Path? (Definition, Vorzeichen, Startrichtung und Kurve, Beispiel mit 19 Yards bei minus zwei Grad)
• TrackMan: What is Smash Factor? (Face to Path und Treffpunkt als Ursachen eines tiefen Smash Factor)
• golfsimulators.ch: Indoor-Golf-Training (81 Anlagen mit Coaching, Stand 18. September 2026)