Swinging strike rate (SwStr%) is the share of a pitcher's pitches that hitters swing at and miss. The 2026 league average was 10.8%, and 13% or better put a pitcher among the best bat-missers in baseball: only 12 of the 46 qualified starters on FanGraphs got there. It's the best single check on whether a pitcher's strikeouts are real, because it measures the missed bats that most of those strikeouts are built on.
What a good swinging strike rate looks like
Here's the 2026 range among qualified starters, from the same FanGraphs leaderboard.
| Pitcher, 2026 | SwStr% | Strikeout rate |
|---|---|---|
| Jacob Misiorowski | 17.6% | 37.9% |
| Jacob deGrom | 15.9% | 30.1% |
| Gavin Williams | 15.0% | 33.2% |
| MLB average, all pitchers | 10.8% | 22.1% |
| Nick Martinez | 8.2% | 15.1% |
| Seth Lugo | 7.6% | 17.8% |
Every strikeout rate in that table sits between about 1.8 and 2.4 times the pitcher's SwStr%, and the league as a whole came in at almost exactly double. Double a pitcher's SwStr% and you have a fair first guess at the strikeout rate they should be running. Relievers ran a little higher as a group, 11.1% to the starters' 10.7% on FanGraphs, so compare a reliever with other relievers.
A swinging strike is a swing and a miss
A swinging strike is any pitch the hitter swings at and misses, whether it's strike one or strike three. A foul ball doesn't count, since the bat touched the ball. FanGraphs defines SwStr% as swings and misses divided by total pitches, so every pitch goes in the bottom number, including the ones the hitter takes. You'll find it on every pitcher's FanGraphs page and on the Plate Discipline tab of its leaderboards.
Those misses are where strikeouts come from. About three in four strikeouts in 2026 ended on a swinging third strike, and nearly all the rest were called, per Baseball Savant's Statcast search.
FanGraphs also warns against mixing SwStr% up with whiff rate, which divides the misses by swings instead of pitches. Savant reports misses per swing, so its numbers run much higher: hitters came up empty on 25.1% of their swings in 2026, and Jacob Misiorowski's 17.6% SwStr% on FanGraphs shows up as a 37.3% whiff rate on his Savant page. Both are useful. Two pitchers with the same whiff rate can post different SwStr% if hitters swing at one of them more often, and getting those swings is part of the pitcher's skill.
Missed bats keep a strikeout rate honest
FanGraphs' Alex Chamberlain checked five seasons of pitchers who threw 100 or more innings. SwStr% lined up with strikeout rate at a 0.83 correlation, and a pitcher's SwStr% one year lined up with the next year's at 0.74. That second number is the one that matters for predicting, because it means missing bats is a skill that carries over. He also found SwStr% tracked FIP at 0.50, since strikeouts are one of FIP's inputs.
Chamberlain uses it to spot strikeout rates that may drift toward what the swinging strikes suggest, and the 2026 leaderboard has two clean cases. Nolan McLean struck out 26.0% of hitters on a 9.6% SwStr%, under the league average. Shota Imanaga went the other way, with a 14.4% SwStr% and a 24.6% strikeout rate. By that logic, McLean's strikeout rate is the one more likely to slip in 2027, and Imanaga's has room to climb.
It takes about five starts to mean something
SwStr% isn't instant. In the same study, Chamberlain found a pitcher's swinging strike rate becomes acceptably reliable after about 400 pitches and keeps getting sharper until 700 to 800 pitches. Starters threw 83 pitches a start on average in 2026, per FanGraphs, so that's about five starts to the first mark and nine or so to the second.
MacKenzie Gore is the 2026 case. Through April he'd struck out 31.6% of hitters in six starts on an 11.6% SwStr%, per the FanGraphs March/April split. That strikeout rate was 2.7 times his SwStr%, well past the usual double. By the end of the season he was at 23.2% on an 11.2% SwStr%, almost exactly double.
Single pitches settle faster. By Chamberlain's numbers, a changeup's swinging strike rate is reliable after about 130 of them, a curveball's after about 180, and a four-seamer's after about 220. When a pitcher adds a new pitch in April, its misses tell you something real well before the rest of their line does. The small samples post covers how long the other numbers take.
Sliders and splitters miss the most bats
Here's how often hitters missed when they swung at each of the common pitches in 2026, from Savant's Statcast search.
| Pitch | Misses per swing, 2026 |
|---|---|
| Splitter | 34.3% |
| Slider | 33.3% |
| Changeup | 31.4% |
| Four-seam fastball | 21.8% |
| Sinker | 13.6% |
That's why so many strikeout pitchers finish hitters with a slider or a splitter, and why a pitcher who leans on sinkers can have a good year with few strikeouts. When a pitcher's mix shifts toward the pitches at the top of this list, expect their SwStr% to follow.
Strikeouts get harder the longer a starter goes
Against starters in 2026, hitters struck out 24.2% of the time on their first trip through the order, 20.7% on the second and 19.4% on the third, per Baseball-Reference. Put another way, 82% of starters' strikeouts came in the first two times through.
For a strikeouts pick, that makes the first 18 hitters the ones that count, and it's why a starter's pitch count matters as much as their SwStr%. If they're at 80 pitches after four innings, the strikeouts they still need have to come against hitters who've already seen them twice.
The lineup matters as much as the arm. In 2026 the Reds struck out in 25.5% of their plate appearances and the Rays in 18.8%, per FanGraphs. The same starter has a different strikeout outlook against each of them, so check who's hitting before you trust the arm alone.
You can watch all of this during a start. Savant's Gamefeed logs every pitch as the game goes, so you can see whether hitters are still missing the breaking ball in the fifth the way they were in the first. The MLB watching post covers what else to track while a game is on.
How SwStr% changes a strikeouts pick in GAGE
Say a starter has struck out 30% of hitters through four starts, but their SwStr% is 9.5%, under the 10.8% league average. The GAGE menu has them at "Strikeouts 6+" with YES at 48%, so NO is the 52% side: +4.8 if they stop short and −5.2 if they get there.
A 30% strikeout rate on 9.5% swinging strikes is running on something other than missed bats, and Chamberlain's research says that kind of strikeout rate can drift toward what the swinging strikes suggest. That's your case for NO. Flip the numbers (a 20% strikeout rate on a 14% SwStr%) and the same logic points to YES. The scoring page has the full rules, and GAGE is on the App Store when you want to make the pick.