One statistic that has always confused me in baseball is OPS. OPS is the sum of the on base percentage (OBP) and slugging percentage (SLG) or OBP + SLG. I first started noticing this statistic when I started playing fantasy baseball and the only reason I paid attention to it was for drafting players with a high percentage.  After the draft I really didn’t follow this statistic because I truly didn’t understand it. If I needed to pick up a player I would auto rank players based on other statistics like average (AVG), runs (R), home runs (HR), runs batted in (RBI) and stolen bases (SB). So, outside of fantasy sports it’s a statistic that I really don’t follow as a baseball fan.

How to Calculate On Base Percentage (OBP)

OBS is the sum of hits (H), walks or bases on balls (BB), and the number of hits by a pitch (HBP) divided by the sum of at bats (AB), BB, sacrifice flies (SF), and HBP.

OBP = (H + BB + HBP) / (AB + BB + SF + HBP)

How to Calculate Slugging Percentage (SLG)

SLG is the sum of types of hits or total bases (TB) like singles (1B), doubles (2B)(x2), triples (3B)(x3), and HRs(x4) divided by the total of at bats (AB).

SLG = (1B) + (2B x 2) + (3B x 3) + (HR x 4) / AB or

SLG = TB / AB

How to Calculate OPS

OPS = OBP + SLG or

OPS = (H + BB + HBP) / (AB + BB + SF + HBP) + (1B) + (2B x 2) + (3B x 3) + (HR x 4) / AB

Rewriting the expression for OPS using a common denominator:

OPS = AB(H + BB + HBP) + TB(AB + BB + SF + HBP) / AB(AB + BB + SF + HBP)

I know these formulas may sound confusing, but once you start to break it down into smaller formulas which just happen to be other more common baseball statistic it becomes easier to understand.

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