Enter the hit breakdown to get slugging percentage (SLG) — total bases per at-bat, the standard measure of power.
Slugging percentage (SLG) is total bases divided by at-bats — the average number of bases a hitter earns per at-bat. It is the standard measure of power, because unlike batting average it gives a double twice the credit of a single and a home run four times.
A slugging percentage of .500 means the player averages half a base per at-bat. Because extra-base hits count for more than one base, SLG can climb above 1.000 — the theoretical ceiling is 4.000, a home run every at-bat. SLG is the second half of OPS, and the gap between a player's slugging and their batting average is a quick read on how many of their hits go for extra bases.
Softball uses the same definition. In slowpitch, where extra-base hits are frequent, slugging percentages tend to run high; in youth fastpitch on small fields they are usually more modest.
SLG = Total Bases ÷ At-Bats, where Total Bases = Singles + (2 × Doubles) + (3 × Triples) + (4 × Home Runs)
Total bases count only bases earned by the hit itself. If a batter hits a single and takes second on a throwing error, that is one total base, not two. Stolen bases and advancing on a wild pitch are not total bases either.
At-bats are the same as in batting average: plate appearances minus walks, hit-by-pitches, sacrifice bunts, sacrifice flies and catcher's interference. Walks do nothing for slugging — a walk is not a base in this formula.
If your scorebook records total hits rather than the breakdown, singles = hits − doubles − triples − home runs. The calculator asks for each type separately so nothing gets double counted.
Your player's spring so far: 40 at-bats with 8 singles, 3 doubles, 1 triple and no home runs (12 hits in total).
Enter those numbers above and you will see .425, with 17 total bases shown underneath.
In the 2025 MLB regular season the league slugged .404 (calculated from official MLB Stats API team totals; 2024 was .399). The tiers fans generally use:
| Level | Slugging percentage | What it means |
|---|---|---|
| MLB, 2025 league average | .404 | Ordinary power |
| MLB, good | .450+ | A hitter you want in the middle of the order |
| MLB, excellent | .500+ | Legitimate power threat |
| MLB, elite | .550+ | Among the game's best sluggers |
| Youth (8U–14U) | Varies widely — judge the trend, not the number | Field size changes everything: a 200-foot fence at 10U makes home runs that are fly outs at 14U |
Youth slugging is even more sensitive to context than batting average. Fence distance, the ball the league uses, how often outfielders misplay balls into "triples", and a sample of 40 at-bats all swamp the underlying skill. Rather than chasing a number, watch whether the gap between the player's slugging and their batting average is growing — that gap is extra-base hits, and a growing gap means they are driving the ball harder than they were. Compare against last season on the same field size and against the league leaderboard, not against the MLB table.
For a young hitter, slugging shows the transition from making contact to driving the ball — the swing change that turns groundball singles into gap doubles usually shows up here before it shows up in the average. Log the hit type (a printable scorecard that distinguishes 1B, 2B, 3B and HR is all you need) and check the number every few weeks.
MyBallPlayer works out total bases and slugging automatically from the games you log and shows the season curve alongside average and OBP, so the trend is obvious without a spreadsheet.
Add up total bases (single = 1, double = 2, triple = 3, home run = 4) and divide by at-bats. Example: 8 singles, 3 doubles and 1 triple in 40 at-bats = (8 + 6 + 3) ÷ 40 = .425.
In MLB the 2025 league average was .404; .450 is good, .500 is excellent and .550+ is elite. For youth players, field size and small samples make a fixed target meaningless — watch the gap between slugging and batting average grow over the season instead.
Batting average treats every hit the same. Slugging weights hits by bases reached, so it measures power, not just contact. A player with a .300 average and a .425 slugging gets a lot of extra-base hits.
Yes. Because extra-base hits are worth more than one base, SLG can exceed 1.000 — the theoretical maximum is 4.000, a home run in every at-bat.
No. A walk is not a base in the total-bases formula and is not an at-bat either, so walks have no effect on slugging percentage.
Yes, with exactly the same formula. Slowpitch slugging percentages tend to run high because extra-base hits are common; youth fastpitch numbers are usually more modest.