Bases earned per at-bat
Slugging percentage is total bases divided by at-bats — the average number of bases a hitter earns each time up. A double counts double, a home run quadruple, which is why it measures power rather than just contact. It is reported to three decimals, like a batting average, and can exceed 1.000.
What the number means
| SLG | Read as |
|---|---|
| under .400 | Below-average power |
| .400–.500 | Solid, sustained production |
| .500–.600 | Excellent power hitter |
| .600–.700 | Elite; among the best in the game |
| over .700 | Historically dominant, rare |
The ceiling is 4.000 (a home run every at-bat). Ruth's .847 single season and .690 career are the practical limits anyone has reached.
ISO and OPS: what SLG feeds into
- ISO (isolated power). SLG minus batting average. It strips out singles to show pure extra-base ability; .200 or higher signals a real power threat.
- OPS. On-base percentage plus SLG, combining the two halves of offense in one number. An OPS of 1.000 or more is elite.
- Sample size. SLG swings wildly early in a season and only settles over a few hundred at-bats, so a small-sample figure is not yet meaningful.
Common questions
How is slugging percentage calculated?
Add up total bases (a single is 1, a double 2, a triple 3, a home run 4) and divide by at-bats. A batter with 20 singles, 10 doubles, 2 triples and 8 home runs in 150 at-bats has 78 total bases and a .520 SLG.
What is a good slugging percentage?
The MLB career average sits around .400 to .420. Above .500 is excellent, above .600 is elite. Babe Ruth holds the career record at .690.
How is SLG different from batting average?
Batting average counts every hit as one, so a single and a home run look the same. Slugging weights hits by bases earned, so it rewards power. A hitter with only singles can post a strong average but a weak SLG.
