What happens if your ball hits another ball on the green?
If your ball hits another ball at rest on the putting green during stroke play, you get a 2-stroke penalty under Rule 11.1a — your ball is played from where it ends up, and the other ball is replaced in its original spot. In match play, no penalty applies to either player.
The situation
You putt from the putting green and your ball rolls into another player's ball that was also on the green. Both balls move.
The rule
Under Rule 11.1a, there is a specific exception for the putting green: if you play a stroke from the putting green and your ball hits another ball at rest on the green, you incur a 2-stroke penalty in stroke play. The other ball must be replaced in its original position. Your ball is played from where it ends up. In match play, there is no penalty — play both balls from where they lie, and the moved ball is replaced. The 2-stroke penalty only applies when both balls are on the green. If either ball was off the green, no penalty applies.
Real example
You're putting from 20 feet on the green. Your partner's ball is on your line six feet from the hole — they forgot to mark it. You putt, hit their ball, your ball goes in. In stroke play: your ball counts, but you add 2 penalty strokes. Their ball is placed back where it was.
What to do on the course
- Always ask other players to mark their ball if it's anywhere near your putting line
- If both balls were on the green: add 2 strokes, play your ball from where it ended up
- The other ball goes back to its original position regardless
- In match play, no penalty — carry on, replace the moved ball
Penalty
2-stroke penalty in stroke play. No penalty in match play.
What if the ball you hit was yours?
The penalty only applies when your ball in motion hits another ball at rest on the putting green. If you putt and hit your own ball that you forgot to mark (because you played a second ball under Rule 20.1c, for example), that's not "another ball" — it's your ball in play. You play it as it lies with no penalty under Rule 11.1a. The 2-stroke penalty in stroke play is strictly for hitting a fellow competitor's ball (or an opponent's ball in match play) that was at rest on the green when you played from the green.
Keep reading: strokeplay · match play
Exceptions that change the answer
- The player's ball in motion on the putting green hits another ball that is at rest on the putting green, and both balls were on the green before the stroke. → The player receives the general penalty of two strokes.
- The player's ball in motion from anywhere other than the putting green accidentally hits a person, animal, or moving outside influence and comes to rest on that person, animal, or moving influence. → The player must not play the ball as it lies; instead, the player must take relief by dropping the original ball.
Frequently asked questions
Do I get penalized if my putt hits another ball on the green?
Yes, in stroke play you get a 2-stroke penalty under Rule 11.1a if your ball is on the putting green when you play the stroke and it hits another ball also on the green. In match play, there is no penalty.
What happens to the other ball after it gets hit?
The other ball must be replaced in its original position, regardless of whether you're in stroke play or match play. If the original spot isn't known exactly, it must be estimated.
What if one of the balls was off the green — does the penalty still apply?
No. The 2-stroke penalty only applies when both balls are on the putting green at the time of the stroke. If either ball was off the green, Rule 11.1a's exception doesn't kick in and there is no penalty.
My ball went in the hole after hitting the other ball — does it count?
Yes, your ball counts as holed. You still add the 2-stroke penalty in stroke play, so your score for the hole is the number of strokes plus two. In match play, you win the hole with no penalty.
Can I avoid the penalty by asking my opponent to mark their ball?
Absolutely — and you should. Before playing any putt, you can ask any other player to mark and lift their ball if it might interfere with your stroke. That's the simplest way to avoid the penalty entirely.
What if I hit my own ball that I forgot to mark on the green?
No penalty under Rule 11.1a — that rule only covers hitting another ball at rest on the green. Your ball is played from where it ends up. If you played a second ball under Rule 20.1c and hit the first one, the first ball is your ball in play; the second ball is abandoned.
What if I hit another player's ball thinking it was mine?
That's a wrong ball situation (Rule 6.3c), not a collision. In stroke play you incur two penalty strokes and must correct the mistake by playing your own ball; in match play you lose the hole immediately. See penalty for hitting a wrong ball for the full procedure.
Does it matter if the other ball was marked but not lifted?
No. A marked ball that hasn't been lifted is still a ball at rest on the putting green. If your putt hits it, the 2-stroke penalty in stroke play still applies. The mark doesn't change its status — only lifting it removes it from play.
What if I'm putting from the fringe and hit a ball on the green?
No penalty. The Rule 11.1a exception only triggers when you play a stroke from the putting green and hit a ball at rest on the putting green. Fringe is not the putting green, so the exception doesn't apply — play both balls as they lie.