Baseball Glossary › Strikeout Rate
Strikeout Rate (K%)
Strikeout rate (K%), also called strikeout percentage, is the share of plate appearances that end in a strikeout. For hitters it is strikeouts divided by plate appearances; for pitchers it is strikeouts divided by batters faced. K is baseball shorthand for a strikeout. Hitters want a low K%, pitchers a high one.
Formula
Worked example (illustrative numbers): a hitter strikes out 132 times in 600 plate appearances.
K% = 132 / 600 = 0.220, or 22.0 percent
What to Know
For hitters, FanGraphs offers a rough rule of thumb, noting that league averages vary by year: about 20 percent is average, 16 percent above average, 12.5 percent great and 10 percent excellent, with 25 percent or higher in poor territory. A high strikeout rate can still work if a hitter brings power and walks, a point FanGraphs also makes.
For pitchers the scale flips. FanGraphs' pitcher table puts about 20 percent at average and 27 percent at excellent. K% per batter faced is generally preferred to strikeouts per nine innings, because K/9 rises when a pitcher allows more baserunners and faces more batters per inning.
Strikeout rate pairs with walk rate. For pitchers, the gap between the two tells a similar story to the strikeout-to-walk ratio.
Frequently Asked Questions
How do you calculate strikeout percentage?
Divide strikeouts by plate appearances for a hitter, or by batters faced for a pitcher, then multiply by 100. A hitter with 132 strikeouts in 600 plate appearances has a 22.0 percent strikeout rate.
What does K mean in baseball stats?
K is the scorekeeping symbol for a strikeout. In stat abbreviations it stands for strikeouts, so K% is strikeout rate, K/9 is strikeouts per nine innings and K/BB is strikeouts divided by walks.
What is a good strikeout rate for a hitter?
FanGraphs' rule of thumb puts about 20 percent at average and 16 percent above average, with 12.5 percent great and 10 percent excellent. League strikeout levels change over time, so compare within the same season.
What is a good strikeout rate for a pitcher?
For pitchers higher is better. FanGraphs' rough guide puts about 20 percent at average, 22 percent above average, 24 percent great and 27 percent excellent. Relievers tend to run higher than starters.
What is the difference between K% and K/9?
K% is strikeouts per batter faced, while K/9 is strikeouts per nine innings. K/9 can look better for a pitcher who allows many baserunners, because he faces more batters each inning, so K% is the cleaner rate.
Is a strikeout worse than other outs for a hitter?
It removes any chance of a hit, an error or moving a runner, so it is a guaranteed out. FanGraphs notes, though, that hitters with high strikeout rates can still be valuable if they hit for power and walk.
Related Terms
Sources
- MLB.com Glossary: Strikeout Rate (K%)
- FanGraphs Library: K% and BB%
- FanGraphs Library: Strikeout and Walk Rates (pitchers)
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