Help on the green.

The phone is losing track of where it is. Walk at about half your normal pace and keep the camera on the grass, not the sky or your feet. Hold the phone at chest height, tilted down. Turn your whole body instead of flicking your wrist. In deep shade or low light, give tracking a second to settle before you walk.

Stand a step or two closer and aim again, with the ball or cup in the middle of the screen. Make sure you walked the line between them so that part of the green is scanned.

Check the green speed first: speed has a big effect on how much a putt breaks. If putts keep breaking more than the read, the green is faster than your setting; if less, slower. Club greens are usually 9 to 11. Measure it with one roll, or pick the closest preset. Then check the confidence rating: if it's low, walk the line again more slowly and re-read.

One cup is the width of the hole, about 4¼ inches. “2 cups out” means aim about two hole-widths outside the cup.

How long the putt effectively is once slope is included. An 11-foot uphill putt might play 12 feet; hit it with 12-foot pace.

On the home screen, tap Measure with a roll. Roll any ball 8 to 15 feet across the green while the camera follows it. For the most accurate number, roll one back the other way to cancel out slope, then tap Use.

Tap Start round, pick your course and the hole you're starting on. Read your first putt on each green, then log how many putts it took. Plumb Bob keeps the scorecard and gives you a putting score and a recap at the end. You can change the hole, edit a hole or mark a green you didn't read.

Each putt is scored with strokes gained: compared with the average number of putts a PGA Tour player takes from the same distance. Positive is better than tour average; negative shows strokes lost.

Three full reads, so you can try it on a real green. Plumb Bob Pro unlocks unlimited reads and rounds, green-speed calibration and stats for $9.99 a month or $59.99 a year, with a free week for new subscribers.

On your iPhone open Settings, tap your name, then Subscriptions, then Plumb Bob Pro. Cancel at least 24 hours before renewal. You keep Pro until the end of the period you paid for, and cancelling during the free week means you aren't charged.

Sign in with the same Apple ID, then open Plumb Bob and tap Restore on the Pro screen or in Settings.

Apple handles App Store payments, so request a refund at reportaproblem.apple.com.

No. It works on any iPhone with iOS 17. iPhone Pro models with LiDAR measure the green in depth for the most precise reads. Other iPhones use camera feature points and give rougher reads; scan slowly in good light.

No. Under Rule 4.3 of the Rules of Golf, using a device to read the slope of a green during a competition round is a breach. Plumb Bob is for practice, lessons and friendly rounds.

No. Reads run entirely on your iPhone. Only subscriptions and the nearby-course search go online.