Slugging Percentage Calculator

What the slugging percentage calculator does

Batting average treats a soft single and a 450-foot home run as exactly the same thing, which is plainly a bit unfair to the home run. Slugging percentage is the stat that fixes that. It measures power, the average number of bases a hitter earns per at-bat. This tool works it out. You give it a player's singles, doubles, triples, home runs, and at-bats, and it returns the slugging percentage.

Because it weights hits by how many bases they are worth, it is one of the best single measures of how much damage a hitter does when they connect.

How to use it

1. Enter the singles, doubles, triples, and home runs a hitter recorded.
2. Enter the at-bats. Only at-bats go on the bottom, walks and hit-by-pitches are left out entirely.

If you only know a player's total hits rather than the breakdown, you can find the singles by subtracting the doubles, triples, and home runs from the total hits. Press Calculate for the slugging percentage, or Reset to clear the fields.

How slugging percentage is worked out

First it adds up total bases, with each hit worth the number of bases it earns, then it divides by at-bats:

Slugging percentage = (1B + 2×2B + 3×3B + 4×HR) ÷ at-bats

So a single is worth 1 base, a double 2, a triple 3, and a home run 4. That weighting is the whole idea. A double is not literally twice as valuable as a single in terms of scoring runs, but counting it as two bases is a clean, sensible way to reward extra-base power, and it works well. The result is shown to three decimals.

An example with real numbers

Take a big power season: 85 singles, 36 doubles, 1 triple, and 58 home runs in 559 at-bats.

• Total bases = 85 + (2 × 36) + (3 × 1) + (4 × 58) = 85 + 72 + 3 + 232 = 392
• Slugging percentage = 392 ÷ 559 = .701

A .701 slugging percentage is monstrous, the kind of figure only the very best power hitters reach across a full season. Notice how the 58 home runs alone contributed 232 of those 392 bases. That is the weighting doing its job, letting raw power dominate the number the way it dominates a game.

Why it can go above 1.000

Here is a quirk that surprises people. Batting average and on-base percentage can never go above 1.000, because they are shares of something. Slugging percentage can, because it counts bases, not successes. If a hitter homered in every single at-bat, they would earn four bases per at-bat, for a slugging percentage of 4.000. Nobody comes anywhere near that over a season, of course, but in a single game a player can easily slug above 1.000. As for what is good over a full season, the major league average usually sits around .400, anything above .450 is strong, and .500 and up is elite, All-Star power. The highest full-season marks in history live in the mid .800s, which shows just how far .500 already is above the crowd.

Power versus average, and isolated power

Slugging is the third number in the slash line, average then on-base then slugging, and it is the one that separates singles hitters from sluggers. Two players can both bat .280, but if one sprays singles and the other launches 35 home runs, their slugging numbers will be miles apart. There is even a neat companion stat for this, called isolated power, or ISO, which is just slugging percentage minus batting average. It strips the singles out and leaves only the extra-base punch, so a hitter at .300 with a .500 slugging has a .200 ISO, while a hitter at .230 who still slugs .500 has a .270 ISO and is generating that power off fewer hits. Slugging tells you the raw power output, and average alongside it tells you how that power is packaged.

Questions people ask

How do you calculate slugging percentage?

Add up total bases, counting a single as 1, a double as 2, a triple as 3, and a home run as 4, then divide by at-bats. The result is shown to three decimals.

What is a good slugging percentage?

The major league average is usually around .400. Above .450 is strong, and .500 or higher is elite power. The best single seasons ever reach into the mid .800s.

Can slugging percentage be over 1.000?

Yes. It counts bases rather than successes, so the ceiling is 4.000, a home run every at-bat. Over a single game it is quite possible to slug above 1.000, though no one sustains that over a season.

Do walks count in slugging percentage?

No. Only at-bats and the hits within them count. Walks and hit-by-pitches are left out entirely, since slugging is meant to measure power, not patience. On-base percentage is the stat that values walks.

References

1. MLB.com Glossary, Standard Stats: Slugging Percentage (SLG). https://www.mlb.com/glossary/standard-stats/slugging-percentage