Slugging Percentage Calculator
Enter a batter's hit breakdown and at-bat total to calculate slugging percentage (SLG), Isolated Power (ISO), and OPS when you also supply on-base percentage. SLG measures how many bases a hitter earns per at-bat, weighting extra-base hits more heavily than singles. The result includes a gauge showing where the figure lands against MLB benchmarks, a bar breakdown of bases by hit type, and a step-by-step walkthrough of the math.
Formula
Worked example
A batter with 85 singles, 30 doubles, 4 triples, 35 home runs, and 550 at-bats: Total Bases = 85 + 60 + 12 + 140 = 297. SLG = 297 / 550 = .540. AVG = 154 / 550 = .280. ISO = .540 - .280 = .260.
What is slugging percentage?
Slugging percentage (SLG) measures how many bases a batter earns per official at-bat. Unlike batting average, which treats every hit as equal, SLG multiplies each hit by the number of bases it produces: singles count as 1, doubles as 2, triples as 3, and home runs as 4. The result is a decimal that can theoretically range from .000 (no hits) to 4.000 (every at-bat a home run), though real-world career figures typically fall between .300 and .700. The all-time career record belongs to Babe Ruth at .6897. Despite the name, SLG is an average, not a true percentage - it tells you the average number of bases per plate appearance.
SLG formula and how at-bats work
The formula is: SLG = (1B + 2 x 2B + 3 x 3B + 4 x HR) / AB. Official at-bats exclude walks, hit-by-pitches, sacrifice flies, and sacrifice bunts, because those are not treated as opportunities to get a hit. That is why a batter can have a plate appearance that does not register as an at-bat. If you only know total hits rather than the breakdown, calculate singles as: Singles = Total Hits - Doubles - Triples - Home Runs.
Isolated Power (ISO) and OPS
Isolated Power strips the single out of SLG to reveal pure extra-base power: ISO = SLG - AVG. A batter with identical SLG can have very different ISO depending on how they achieve their bases - one who relies on singles has low ISO while a home-run hitter has high ISO. OPS (On-Base Plus Slugging) adds OBP and SLG into one number. It is imperfect mathematically because OBP uses plate appearances as its denominator while SLG uses at-bats, but it remains one of the most widely cited single offensive statistics because it captures both getting on base and hitting for power. An OPS above .900 is elite and above .800 is very good.
How to interpret your SLG result
The league-average SLG in MLB has typically ranged from about .400 to .430 over the modern era. A figure above .450 is above-average, .500 or more is excellent, and .550 or higher is elite. Below .350 is often a liability unless the player contributes defense, speed, or on-base ability. Context matters: a catcher with .400 SLG is far more valuable than a corner outfielder with the same figure. Also compare SLG over time - a batter with declining SLG may be losing power as they age or battling injury.
MLB Slugging Percentage benchmarks
| SLG range | Label | What it means |
|---|---|---|
| .550 and above | Elite | MVP-caliber power; all-time greats like Babe Ruth (.6897 career SLG) and Barry Bonds |
| .500 - .549 | Excellent | Perennial All-Star power, top-tier run production |
| .450 - .499 | Above Average | Solid run-producing bat, likely a lineup cornerstone |
| .390 - .449 | Average | Near the MLB average most seasons (.400-.430 range) |
| .300 - .389 | Below Average | Limited extra-base impact; may survive in the lineup elsewhere |
| Below .300 | Poor | Extremely light power; typically not sustainable in a starting role |
General reference tiers used by analysts to evaluate batter power production. Exact league averages fluctuate year to year.
Frequently asked questions
What is a good slugging percentage?
In MLB, a SLG around .400 to .420 is near league average. Above .450 is above average, .500 or more is excellent, and .550 or higher is elite. Context matters: league-wide SLG shifts with offensive eras and rule changes, so comparing a player to their contemporaries is more meaningful than using a fixed threshold.
How is slugging percentage different from batting average?
Batting average counts every hit the same way: one hit divided by one at-bat. Slugging percentage weights hits by how many bases they produce, so a home run counts four times as much as a single. This means two batters can have identical batting averages but very different slugging percentages if one hits for more power.
Do walks count in slugging percentage?
No. Walks (base on balls), hit-by-pitches, sacrifice flies, and sacrifice bunts are excluded from both the numerator and denominator of SLG. They are also excluded from at-bats. On-base percentage (OBP) is the stat that captures a batter's ability to reach base by other means, which is why OPS (OBP + SLG) is used to get a fuller picture.
What is Isolated Power and how is it calculated?
Isolated Power (ISO) measures how many extra bases beyond singles a batter averages per at-bat. It is calculated as SLG minus batting average (AVG). A batter with SLG of .480 and AVG of .280 has an ISO of .200, which is considered strong power production. The league average ISO is typically around .130 to .160 in the modern era.
Who holds the all-time career slugging percentage record?
Babe Ruth holds the all-time career slugging percentage record at .6897, a figure that has stood for over 80 years. The single-season record belongs to Barry Bonds, who posted an astronomical .863 slugging percentage in his 2001 season (73 home runs). For reference, a career SLG above .500 is considered Hall-of-Fame caliber production.