Baseball Hitting Stats Glossary: AVG, OBP, SLG, OPS & wOBA

July 18, 2026

Box scores and stat sheets throw a lot of hitting abbreviations at once. Here’s what the most common ones mean, in plain English, alongside the stats the batting average calculator computes directly.

AVG (Batting Average)

Hits divided by official at-bats, rounded to three decimals and written without a leading zero. The oldest and most widely recognized hitting stat, but it only measures how often a batter gets a hit — it ignores walks entirely and treats a single and a home run as identical. See what’s a good batting average by level for benchmarks from youth ball through MLB.

OBP (On-Base Percentage)

The rate at which a batter reaches base safely by any means — hit, walk, or hit-by-pitch — calculated as (H + BB + HBP) ÷ (AB + BB + HBP + SF). OBP is what separates a genuinely patient hitter from a free-swinger with the same batting average, since walks count toward OBP but not toward AVG.

SLG (Slugging Percentage)

Total bases earned per at-bat, calculated as Total Bases ÷ At-Bats. SLG weights hits by how many bases they’re worth rather than counting every hit the same, which is why a power hitter with fewer total hits than a contact hitter can still post a higher SLG.

OPS (On-Base Plus Slugging)

The simple sum of OBP and SLG. It’s the most common single-number shorthand for overall offensive value because it captures both plate discipline (via OBP) and power (via SLG) in one figure. See the batting average calculator for MLB benchmark tiers, or common batting stat mistakes for what trips people up when calculating it by hand.

Total Bases

The weighted sum of all hits in a stat line, where a single counts as 1, a double as 2, a triple as 3, and a home run as 4:

Total Bases = Singles + (2 × Doubles) + (3 × Triples) + (4 × Home Runs)

Total bases is the numerator of the SLG formula, and it’s also tracked as its own counting stat in many box scores, usually abbreviated “TB.”

ISO (Isolated Power)

A power-only stat that strips batting average out of slugging percentage, calculated as SLG − AVG. Because SLG already includes every single, subtracting AVG removes the “getting a hit at all” component and leaves only the extra-base-hit contribution. An ISO above .200 is typically considered strong power production at the MLB level; below .100 suggests a hitter with little extra-base pop.

wOBA (Weighted On-Base Average)

A more advanced offensive stat that assigns a different run value to each way of reaching base — a walk, a single, a double, a triple, and a home run each get their own statistically derived weight, rather than OPS’s simpler approach of just adding two rate stats together. wOBA is scaled to look roughly like OBP (a .320 wOBA is around league average, .370+ is very good), and many analysts consider it a more accurate single-number offensive metric than OPS because OPS treats a point of OBP and a point of SLG as equally valuable, when in reality they aren’t.

BABIP (Batting Average on Balls in Play)

A hitter’s batting average counting only balls put in play — home runs and strikeouts are excluded from both the numerator and denominator. BABIP is used mostly to spot when a hitter’s batting average is running unusually high or low compared to their typical contact quality, since league-average BABIP tends to sit close to .300 over a large enough sample.

Batting Title Qualifier

The minimum playing-time threshold a hitter must reach for their rate stats (AVG, OBP, SLG, OPS) to count toward official league leaderboards. In MLB, the standard is 3.1 plate appearances per team game — roughly 502 plate appearances over a full 162-game season. This is why a player who goes on a hot streak in limited at-bats doesn’t show up atop the batting average leaderboard; the sample size requirement exists specifically to keep small-sample outliers off the official leaderboard.

Qualified At-Bat vs. Plate Appearance

An at-bat and a plate appearance aren’t the same thing. A plate appearance is any trip to the plate that ends the at-bat sequence — including walks, hit-by-pitches, and sacrifices — while an at-bat excludes all of those. This distinction is exactly why AVG (which uses at-bats) and OBP (which effectively factors in the fuller plate-appearance picture) can diverge so much for a patient hitter. See common batting stat mistakes for how mixing these two up produces a wrong AVG or OBP.

Ready to run these formulas on a real stat line? Use the batting average calculator, or see batting average calculator examples for three different hitter profiles worked out step by step.