ISO (Isolated Power) measures exactly that: a hitter’s raw power, stripped away from his singles. It answers the question, «how many extra bases does he generate beyond just making contact?»
How is it calculated?
ISO = Slugging − Batting average
Subtracting the average from the slugging leaves only the value of the extra-base hits: doubles, triples and home runs.
What is a good ISO?
| ISO | Level |
|---|---|
| .250 or higher | Elite power |
| .200 – .249 | Very good power |
| .140 – .199 | Average |
| Below .100 | Little power |
Examples with players
- Sluggers like Manny Ramírez and Juan González lived with elite ISOs, north of .250.
[Live data — MLB API] Current-season ISO leaders: (filled in automatically).
Why it matters
Two hitters with the same batting average can have wildly different power. ISO makes that clear at a glance, which is why it’s the cleanest way to measure pure power.
Related stats
Frequently asked questions
What is a good ISO?
.200 is very good power; .250 or higher is elite.
Why is it called «isolated»?
Because it isolates the power from extra-base hits, removing the effect of singles.
