A launch monitor turns uneven lies from guesswork into numbers. Hit a set of shots from a flat lie to get your baseline, then hit the same club from a slope and compare launch angle, carry, start direction and curve. The difference is what that lie does to your shot. Do that for each lie and your main clubs, and you'll know roughly how much to club up, club down or aim off, based on your own swing rather than a rule of thumb.
Why a launch monitor helps
On the course, you get one shot from each lie and rarely know exactly why it went where it did. Was it the slope, a poor strike, the wind? You can't separate them.
With a launch monitor, you can hit the same lie ten times in a row in still conditions and see the pattern. It's also honest. The numbers show what actually happened at impact, so if you think you've adjusted for a slope and the data says otherwise, you learn something.
You still need a real slope to stand on. A launch monitor on a flat mat only tells you about flat lies.
What to measure
You don't need every number your launch monitor shows. For uneven lies, focus on a few. If you're new to the data, the launch monitor numbers that matter for beginners post explains what each one means.
Launch angle. How high the ball starts. Uphill lies tend to raise it, downhill lies tend to lower it. This is often the clearest change.
Carry distance. How far it flies. Expect uphill lies to carry shorter, and downhill lies to fly lower and often further, with more run. Many launch monitors also estimate total distance, but on a mat the roll figure is a guess, so carry is the number to trust.
Start direction and face angle. Where the ball starts relative to your target. For a right-hander, ball above your feet tends to start and curve left, and ball below your feet tends to go right. Face angle at impact usually shows why.
Curve or spin axis. How much the ball curves, and which way. Sidehill lies often change this as well as start direction.
Strike and attack angle, if your unit measures them. Slopes move the low point of your swing, which is why fat and thin shots creep in. Attack angle and strike location can show this.
A simple session plan
Keep it structured. Random hitting from different slopes won't tell you much.
- Pick one club. A 7-iron is a good start. It's in the middle of the bag and you'll hit it from slopes often.
- Hit a flat baseline. Ten shots from a flat lie. Note the average launch, carry and start direction. Throw out any genuine mishits.
- Set one lie. For example, a gentle uphill lie. Make your setup adjustments for that lie.
- Hit ten shots. Note the same numbers.
- Compare. How much did launch go up? How much carry did you lose? Did the ball start left?
- Repeat at a steeper setting, or switch to another lie.
Over a few sessions, cover all four basic lies with your main irons and a wedge. You'll end up with a personal table: on a gentle uphill lie, my 7-iron launches higher and carries this much shorter. On ball above feet, it starts this far left.
Things you'll probably notice
Everyone's numbers are different, but a few patterns are common.
Loft magnifies the sidehill effect on start direction. With the ball above or below your feet, the tilted face points further off line the more loft it has, so a wedge can start further left or right than you'd expect. Long irons bring a different problem: they're harder to strike cleanly from a sidehill lie, and a poor strike shows up as extra curve.
Gentle slopes still change distance. Even a small uphill or downhill tilt can move your carry by enough to matter, so measure the gentle settings as well as the steep ones.
Your setup changes the result. If you set your shoulders with the slope and move the ball position, the numbers often look different from when you just stand there as you would on flat ground. That's a useful check on your technique, and the data shows whether the adjustment worked.
Strike suffers on some lies. Many golfers find their strike is worse on downhill lies or with the ball below their feet. If the data shows lots of thin or heavy shots on one lie, that's the one to practise most.
Write it down
The numbers are only useful if you keep them. A simple note on your phone works, or a practice journal. Record the club, the lie, the steepness, and the average carry and direction compared with flat. The golf practice journal post has ideas on what to track.
When you're on the course, you then have something better than a rule of thumb. You know that on a moderate uphill lie your 7-iron usually comes up short by a certain amount, and that a ball above your feet with a wedge starts a certain distance left. The how far to aim off on a sloping lie post gives general guides, but your own numbers will be more accurate for you.
Setup tips
If your launch monitor sits beside the ball, as many camera-based units do, check that it's at the right height relative to the hitting surface when you raise or tilt it. Radar units that sit behind the ball are usually less fussy, but check the manufacturer's guidance. Keep the unit itself level and aimed at your target line, even when the hitting surface is tilted.
Libro was built to pair with this kind of practice. It works with any launch monitor, tilts up to 7 degrees along its length and 13 degrees across, and has laser-engraved height lines, so you can set exactly the same lie in each session and compare the numbers properly.