Baseball Advanced Stats Calculator (FIP, WHIP, ERA+)
Calculate advanced pitching stats: FIP, WHIP, ERA+, K/9, and BB/9.
Evaluate pitcher performance beyond traditional ERA with fielding-independent metrics.
Why Advanced Stats? Traditional ERA (Earned Run Average) measures runs allowed per 9 innings, but ERA is influenced by factors outside the pitcher’s control — fielding errors, defensive range, and sequencing luck. Sabermetrics — the advanced statistical analysis of baseball — was popularized by Bill James in the 1970s and 1980s in the United States. Advanced pitching metrics attempt to isolate what the pitcher actually controls: strikeouts, walks, and home runs allowed. These stats became mainstream after Billy Beane’s Oakland A’s (the Moneyball era) famously used them for player valuation in the early 2000s.
FIP: Fielding Independent Pitching FIP = (13 × HR + 3 × (BB + HBP) − 2 × K) / IP + FIP Constant The FIP Constant is calculated to make FIP scale to ERA league-wide (typically around 3.10 for modern MLB). FIP measures only what the pitcher controls: home runs, walks, hit batters, and strikeouts. FIP is on the same scale as ERA, making comparison intuitive. FIP below 3.00: elite. 3.00–3.75: above average. 3.75–4.50: average. Above 5.00: struggling.
WHIP: Walks plus Hits per Inning Pitched WHIP = (Walks + Hits) / Innings Pitched WHIP below 1.00: excellent (allowing fewer than one baserunner per inning). WHIP 1.00–1.20: above average (typical of a mid-rotation starter). WHIP 1.20–1.40: league average. Above 1.50: below average.
ERA+: ERA Relative to League ERA+ = 100 × (League ERA / Pitcher ERA), adjusted for park factors. ERA+ of 100 is exactly league average by definition. ERA+ of 130 means the pitcher’s ERA is 30% better than league average. ERA+ is useful for comparing pitchers across different eras and ballparks.
K/9: Strikeouts per 9 Innings K/9 = (Strikeouts / Innings Pitched) × 9 A K/9 of 10.0+ is considered elite in modern MLB. 7–8 is solid. Below 5 is low. Strikeout rates have risen dramatically in MLB: from ~5 K/9 league average in 1990 to ~8.5 K/9 by 2023.
BB/9: Walks per 9 Innings BB/9 = (Walks / Innings Pitched) × 9 Below 2.0 is excellent control. 2–3 is average. Above 4 is problematic.
K/BB Ratio: Command Metric K/BB = Strikeouts / Walks Above 4.0 is elite command. 3–4 is above average. Below 2 indicates control issues.
HR/9: Home Runs per 9 Innings HR/9 = (Home Runs / Innings Pitched) × 9 Below 0.8 is very good. 1.0–1.3 is average. Above 1.5 is concerning.
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