About

Batting average (BA) is the ratio of base hits to official at-bats, reported to three decimal places without a leading zero. A .300 season is considered elite; the league-wide MLB average has hovered near .250 since 2010. Misrecording even one at-bat shifts the stat by several points at small sample sizes - a 1-for-4 day versus 0-for-4 moves a 100 AB player by .010. This tool computes BA, on-base percentage (OBP), slugging percentage (SLG), and OPS using official MLB formulas. It assumes standard scoring rules: sacrifice bunts do not count as at-bats, walks and hit-by-pitch events factor into OBP only, and sacrifice flies reduce plate appearances for OBP denominators.

Note: this calculator approximates season-level stats from cumulative totals. It does not account for split-game substitutions or retroactive official scorer changes. For platoon splits or park-adjusted metrics like wOBA or OPS⁺, consult a full sabermetric database. Pro tip: track weekly inputs to spot slumps early - a 20-AB rolling window reveals trends faster than season aggregates.

Formulas

The primary metric is batting average, defined as base hits divided by official at-bats.

BA = HAB

On-base percentage measures how frequently a batter reaches base by any non-error, non-fielder's-choice means.

OBP = H + BB + HBPAB + BB + HBP + SF

Slugging percentage weights hits by total bases earned.

SLG = TBAB

Where total bases are computed as:

TB = 1⋅1B + 2⋅2B + 3⋅3B + 4⋅HR

OPS combines both on-base and power into a single metric.

OPS = OBP + SLG

Where: H = total hits, AB = official at-bats (excludes walks, HBP, sacrifices), BB = bases on balls (walks), HBP = hit by pitch, SF = sacrifice flies, 1B = singles, 2B = doubles, 3B = triples, HR = home runs, TB = total bases.

Reference Data

Tier	Batting Avg Range	OBP Range	SLG Range	OPS Range	Assessment
Hall of Fame	.320 +	.400 +	.550 +	.950 +	Historic elite
All-Star	.300 - .319	.370 - .399	.500 - .549	.870 - .949	Perennial star
Above Average	.280 - .299	.350 - .369	.450 - .499	.800 - .869	Quality starter
Average	.250 - .279	.320 - .349	.400 - .449	.720 - .799	MLB average
Below Average	.230 - .249	.300 - .319	.350 - .399	.650 - .719	Defensive specialist
Poor	.200 - .229	.270 - .299	.300 - .349	.570 - .649	Struggling / bench
Mendoza Line	< .200	< .270	< .300	< .570	Replacement level
Notable Career Records (MLB)
Ty Cobb	.366	.433	.512	.945	Highest career BA
Ted Williams	.344	.482	.634	1.116	Highest career OBP
Babe Ruth	.342	.474	.690	1.164	Highest career SLG/OPS
Rogers Hornsby	.358	.434	.577	1.010	Highest NL career BA
Tony Gwynn	.338	.388	.459	.847	Modern contact hitter
Ichiro Suzuki	.311	.355	.402	.757	MLB+NPB combined
Barry Bonds	.298	.444	.607	1.051	Walk king
Mike Trout	.303	.412	.587	.999	Modern 5-tool player
Hit Type & Total Bases
Single (1B)	1 total base				Most common hit
Double (2B)	2 total bases				Extra-base hit
Triple (3B)	3 total bases				Rarest standard hit
Home Run (HR)	4 total bases				Power metric

Frequently Asked Questions

At-bats exclude events where the batter did not have a fair opportunity to get a hit: walks (BB), hit-by-pitch (HBP), sacrifice bunts, sacrifice flies (SF), and catcher interference. Including these would deflate BA for patient hitters. Official MLB Rule 9.02(a) defines an at-bat as a plate appearance minus these excluded events.

Sabermetric research (notably by Russell Carleton / Pizza Cutter) suggests BA stabilizes around 910 at-bats - roughly a full season and a half. Below 200 AB, variance is extremely high. For in-season decisions, OBP stabilizes faster (around 460 AB) and is a more reliable small-sample metric.

If AB equals 0, the calculator returns .000 for BA and SLG. Similarly, if the OBP denominator (AB + BB + HBP + SF) is 0, OBP returns .000. This follows standard scorekeeping convention: no plate appearances means no average to report.

No. The calculator validates that H ≤ AB and that the sum of singles, doubles, triples, and home runs does not exceed total hits. If violated, an error message appears. In real scorekeeping, hits are a strict subset of at-bats by definition.

OPS is the sum of OBP (max theoretical 1.000) and SLG (max theoretical 4.000, if every AB is a home run). The theoretical OPS maximum is 5.000. In practice, career OPS above 1.000 is rare - only Babe Ruth (1.164) and Ted Williams (1.116) achieved it over a full career.

Yes. The formulas for BA, OBP, SLG, and OPS are universal across MLB, NPB, KBO, NCAA softball, and amateur leagues. The only difference is context: a .400 BA in slow-pitch softball is common, while in MLB it has not been achieved for a full season since Ted Williams hit .406 in 1941.