What Is a Perfect Game in Baseball?

Twenty-seven batters come to the plate, and twenty-seven walk back to the dugout. No hits, no walks, no hit batsmen, not even a runner reaching on a fielding error. When a pitcher pulls that off, he has done something that has happened only a couple of dozen times in more than a century of Major League Baseball. That is a perfect game, the cleanest possible outing a pitcher can have.

The definition

A perfect game means every batter the pitcher faces is retired, and no opposing player reaches base by any method for the entire game. In a nine-inning game that is 27 consecutive outs with a spotless slate: no hits allowed, no bases on balls, no batters hit by a pitch, and no runners reaching on defensive errors.

The moment any runner reaches base, for any reason, the perfect game is gone. It can be a clean single, a four-pitch walk, or a routine grounder that a fielder boots. The offence does not even need to score; a single baserunner is enough to end it.

Perfect game vs no-hitter

People often use the two terms loosely, but they are not the same, and the difference matters.

	No-hitter	Perfect game
Hits allowed	None	None
Walks allowed	Permitted	None
Hit batsmen	Permitted	None
Errors letting a runner on	Permitted	None
Runners reach base	Possible	Never

Every perfect game is automatically a no-hitter, because you cannot allow a hit and still be perfect. But the reverse is not true. Plenty of no-hitters include a walk or two, which means a runner reached base and the game was never perfect.

Why it is so rare

Retiring 27 hitters in a row asks a pitcher to be sharp for roughly three hours without a single lapse, and it also asks the eight players behind him to make every play cleanly. One misjudged hop, one throw pulled off the bag, and the perfect game dies through no fault of the pitcher at all.

That shared dependence is part of what makes the feat special. A pitcher can dominate all night and still lose the perfect game to a teammate’s error, which is why defenders playing behind a pitcher chasing perfection feel the pressure just as sharply.

Late-game tension

Baseball has an unwritten tradition around a perfect game in progress: teammates often stop talking to the pitcher in the dugout so as not to jinx it. The tension climbs with every out, because there is no cushion. In a normal game a pitcher can shrug off a hit; here, one mistake erases the whole achievement.

If you want the earlier, more common cousin of this feat, our explainer on the walk-off in baseball covers another of the sport’s dramatic endings. But nothing tops the quiet, mounting pressure of a pitcher three outs from perfection, needing the last few hitters to go down in order to join one of baseball’s smallest clubs.