Why you see these lines everywhere on PGA Tour putting greens

When Tour pros step onto the practice putting green for the first time of the day, their coach and caddie will usually be waiting for them.

More often than not they’ll have set up a putting station for them: A mirror and a chalk line on the ground, set up to a short putt range, usually inside 10 feet.

Almost nothing is the same among those occupying the upper echelon of golf. Golf swings, physical builds, strategies, equipment. Yet canvas a professional putting green, as I did during the U.S. Open a couple of weeks ago, and you’ll see chalk lines everywhere.

So, what’s the point of them?

Why pros use chalk lines

Drawing a chalk line on the ground represents the start line of the putt, and players draw one on the green simply to make sure their putts are starting where they’re intending to start them.

If the ball starts a little left, they’re pulling their putts slightly; the opposite is true if their ball starts right of the line. It’s a quick and easy way to spot immediately what’s going on in your putting, and make small adjustments if necessary.

“Most of the early part of their warmup is focused on start line, alignment…the basics,” says putting coach Stephen Sweeney, who works with multiple PGA Tour players.

The mirror helps with that. Pushes can often be caused by your eyeline pointing too far out to the right, and pulls when your eyes align left. A quick check with a mirror is all it takes to get your eyes where you want them.

While you can probably get away with using a mirror on the green at your home club, you’d probably be banished from the grounds for trying to draw a chalk line. Your best way around that is to use a putting string, which extends between your eyes and the ball. It accomplishes the same thing as a chalk line, but without the mess.