What is wOBA? Definition, Formula, and Example
wOBA (weighted On-Base Average) is a rate stat that credits each offensive event — walk, single, double, triple, home run — by its actual run value, then scales the result to the familiar OBP range. It is the single most accurate summary of a hitter's offensive production on the 0–1 scale.
What Is wOBA?
wOBA (weighted On-Base Average) is a rate stat developed by Tom Tango that measures a hitter's offensive contribution per plate appearance. Unlike batting average, which counts every hit equally, wOBA assigns each offensive event the run value it actually creates in an average scoring environment. It is the best single-number summary of a hitter's overall offensive production and is the foundation of modern front-office evaluation.
wOBA is scaled so that league-average wOBA matches league-average OBP — roughly .315–.325 in a typical season. This makes it easy to read: if you know what a good OBP looks like, you already know what a good wOBA looks like.
wOBA Formula
The 2024 linear weights used by FanGraphs:
wOBA = (0.69 × uBB + 0.72 × HBP + 0.88 × 1B + 1.25 × 2B + 1.58 × 3B + 2.02 × HR) / (AB + BB – IBB + SF + HBP)
Where uBB = unintentional walks. Intentional walks are excluded because they reflect pitcher choice rather than hitter skill.
The weights shift slightly year to year based on the run environment. In a higher-offense era, every event is worth fewer runs, so the coefficients compress. In a lower-offense era (2022), they expand.
Worked Example
A hitter with 600 plate appearances posts the following line:
| Event | Count | Weight | Weighted total |
|---|---|---|---|
| Unintentional BB | 60 | 0.69 | 41.4 |
| HBP | 8 | 0.72 | 5.76 |
| 1B | 110 | 0.88 | 96.8 |
| 2B | 35 | 1.25 | 43.75 |
| 3B | 3 | 1.58 | 4.74 |
| HR | 28 | 2.02 | 56.56 |
| Total | 249.01 |
Denominator = AB (540) + BB (62) – IBB (2) + SF (4) + HBP (8) = 612
wOBA = 249.01 / 612 = .407
A .407 wOBA is elite — roughly top-10 in MLB. For context: .400+ is MVP-tier, .370 is All-Star-tier, .340 is above average, .320 is league average, .290 is a concern.
Why wOBA Beats OPS
OPS (on-base + slugging) is simple but flawed. It treats a walk and a hit-by-pitch as worthless (not counted in SLG) and double-counts totals in a way that weights slugging too heavily relative to its run value. A hitter with a .350 OBP and .500 SLG does not produce the same runs as a hitter with .400 OBP and .450 SLG, even though both have an .850 OPS.
wOBA fixes this by weighting each event by its actual empirical run value. The difference shows up clearly on high-OBP, low-power hitters — guys like Luis Arraez — whose OPS undersells their real offensive contribution while wOBA values them correctly.
wOBA in Legends Deck
Legends Deck card ratings use wOBA as the primary offensive driver, not batting average. A hitter's "Contact," "Power," "Vision," and "Discipline" attributes derive from the component events that build wOBA. This is why you'll see cards with modest batting averages but elite ratings — their walk and power rates make their true offensive output far higher than the traditional triple-slash line suggests.