Calculate slugging percentage (SLG) from hits, doubles, triples, and home runs, plus total bases, ISO, and the bases needed to hit a target SLG.
Slugging Percentage Formula
SLG = (1B + 2*2B + 3*3B + 4*HR) / AB
- SLG is the slugging percentage, shown as a decimal to three places (for example .522)
- 1B is the number of singles
- 2B is the number of doubles
- 3B is the number of triples
- HR is the number of home runs
- AB is the number of at bats (walks, hit by pitch, sacrifices, and catcher’s interference do not count)
The numerator of the formula is total bases (TB): one base for a single, two for a double, three for a triple, and four for a home run. Box scores usually report total hits (H) rather than singles, so the calculator’s default entry mode lets you type H, 2B, 3B, and HR and derives singles for you:
1B = H - 2B - 3B - HR
Along with SLG, the calculator returns total bases, derived singles, batting average (AVG = H / AB), isolated power (ISO = SLG – AVG), and an informal comparison with recent MLB league averages. The second mode inverts the formula to plan ahead: it computes how many total bases you need to reach a target SLG.
TB needed = max(0, ceil( Target SLG * (AB so far + upcoming AB) - TB so far ))
Enter the target SLG and upcoming at bats, optionally including current at bats and total bases. The calculator rounds the exact decimal requirement upward, with a minimum of zero, and checks the limit of four total bases per upcoming at bat. Singles-only, doubles-only and home-runs-only equivalents may overshoot the minimum; a count greater than the available at bats is not feasible.
SLG Benchmarks and MLB League Averages by Season
The first table gives informal descriptions, not official MLB ratings, All-Star selection or MVP criteria. Combined MLB slugging percentages ranged from .395 to .435 across the 2016–2025 regular seasons. League, era and sample size affect comparisons.
| SLG range | Informal description (MLB context) |
|---|---|
| Under .340 | Well below average |
| .340 to .379 | Below average |
| .380 to .429 | About average |
| .430 to .489 | Above average |
| .490 to .549 | High |
| .550 and up | Very high |
The second table shows combined AL/NL regular-season total bases divided by at bats, verified from official MLB totals; MLB Baseball Savant provides league-season context. The displayed 2019 value (.435) is 40 slugging points (.040) above 2022 (.395). These historical values are not current-season forecasts.
| Season | MLB average SLG | Season | MLB average SLG |
|---|---|---|---|
| 2016 | .417 | 2021 | .411 |
| 2017 | .426 | 2022 | .395 |
| 2018 | .409 | 2023 | .414 |
| 2019 | .435 | 2024 | .399 |
| 2020 (60 games) | .418 | 2025 | .404 |
Example Problems
Example 1: a hitter finishes the season with 150 hits in 500 at bats, including 30 doubles, 3 triples, and 25 home runs. First derive singles: 1B = 150 – 30 – 3 – 25 = 92. Total bases = 92 + 2(30) + 3(3) + 4(25) = 92 + 60 + 9 + 100 = 261. SLG = 261 / 500 = .522. Batting average is 150 / 500 = .300, so isolated power is .522 – .300 = .222, a strong power profile.
Example 2: a player is slugging .380 through 100 at bats (38 total bases) and wants to finish at .450 with 100 at bats left in the season. Total bases needed = .450 * (100 + 100) – 38 = 90 – 38 = 52. Over the remaining 100 at bats that is a .520 SLG, which any mix of hits worth 52 total bases achieves, for example 13 home runs, 26 doubles, or 52 singles.
Frequently Asked Questions
Why is it called a percentage if it can be greater than 1?
The name is a historical quirk. SLG is really an average, total bases per at bat, not a share out of 100. It runs from .000 (no hits) to a theoretical maximum of 4.000, which would mean a home run in every at bat. On 2026-10-23 (UTC), MLB’s qualified season and career SLG leaderboards list Josh Gibson first at .982 (1937) and .717, respectively. Barry Bonds recorded .863 in 2001.
What counts as an at bat in the formula?
An at bat is a completed plate appearance minus walks, hit by pitch, sacrifice bunts, sacrifice flies, and catcher’s interference. That is why a player’s at bat total is smaller than their plate appearance total, and why SLG ignores walks entirely. If you use plate appearances in the denominator by mistake, the result will understate the true slugging percentage.
How is SLG different from OPS and ISO?
SLG measures only what happens on hits, so it says nothing about how often a hitter reaches base by walk. OPS fixes that by adding on-base percentage to slugging (OPS = OBP + SLG). ISO strips batting average out of slugging (ISO = SLG – AVG) to isolate extra-base power: a .300 hitter with all singles has a .000 ISO, higher values reflect more extra bases per at bat, with context varying by league, era and sample size. The calculator reports ISO automatically whenever it computes SLG.
