Calculate baseball FIP to evaluate pitcher performance independent of defense. Compare to ERA with HR, BB, HBP, K, and IP inputs.
Fielding Independent Pitching (FIP) is one of the most important metrics in modern baseball analytics. Unlike ERA, which is heavily influenced by the quality of the defense behind a pitcher, FIP isolates the outcomes that a pitcher truly controls: home runs, walks, hit batters, and strikeouts. This makes FIP a much better predictor of future pitcher performance than ERA.
FIP was developed by Tom Tango and works on the principle that pitchers have limited control over what happens once a ball is put in play. BABIP (Batting Average on Balls in Play) fluctuates around .300 for most pitchers regardless of talent, meaning that high or low ERAs are often driven by luck on batted balls rather than pitcher skill. FIP strips away this noise.
This calculator computes FIP from standard pitching statistics, compares it to the pitcher's actual ERA, and provides context through league-average benchmarks across MLB seasons. It also calculates xFIP (which normalizes home run rate) and SIERA for a more complete picture of pitcher quality.
FIP is useful because it strips away the parts of run prevention that pitchers influence only indirectly, leaving the core outcomes they control most directly. That makes it a better tool for comparing pitchers across parks, defenses, and uneven sample sizes when you want a cleaner read on underlying performance.
FIP = ((13×HR) + (3×(BB+HBP)) - (2×K)) / IP + FIP constant. FIP constant ≈ 3.10-3.20 (varies by season, calculated so league FIP = league ERA). xFIP replaces HR with expected HR based on fly ball rate: xHR = FB × league HR/FB rate.
Result: FIP = 3.15
With 18 HR, 50 BB+HBP, 200 K in 190 IP: FIP = ((13×18) + (3×50) - (2×200)) / 190 + 3.17 = 3.15. This closely matches the ERA of 3.20, suggesting the pitcher's results are genuine.
FIP assigns weight to the outcomes pitchers control most directly: home runs, walks, hit batters, and strikeouts. That makes it a cleaner estimate of future performance than ERA when the defense behind the pitcher or random variation on balls in play has distorted the scoreboard result.
When FIP is much lower than ERA, the pitcher may have been unlucky or poorly supported by defense. When ERA is much lower than FIP, the pitcher may have benefited from an unusually strong strand rate, favorable batted-ball outcomes, or park effects that are less likely to persist.
FIP becomes more stable as the sample grows. It is most useful when comparing pitchers with enough innings for the strikeout, walk, and home run profile to mean something, rather than treating one hot month or one bad outing as a full evaluation of skill.
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This worksheet applies the published baseball stat formula for FIP (Fielding Independent Pitching) Calculator. It is a scoring/benchmarking aid that helps compare performance using the standard published definition. Context such as era, park, role, and competition level still matters.
In MLB, a FIP below 3.20 is excellent (All-Star caliber), 3.20-3.80 is above average, 3.80-4.20 is league average, 4.20-4.80 is below average, and above 4.80 is poor.
FIP is a better predictor of future ERA than ERA itself. A pitcher with a 2.50 ERA but 3.80 FIP is likely benefiting from good defense or luck on balls in play and will likely regress.
A FIP well below ERA suggests the pitcher has been unlucky—their defense has let them down, or they've had bad luck on batted balls. Their ERA should improve toward their FIP over time.
The FIP constant is a season-specific number (typically 3.10-3.20) that scales FIP to match league-average ERA. It's recalculated each season using: lgERA - ((13×lgHR) + (3×(lgBB+lgHBP)) - (2×lgK)) / lgIP.
xFIP replaces actual home runs with expected home runs based on fly ball rate and league-average HR/FB%. This further stabilizes the metric by removing HR luck, since HR/FB% fluctuates year to year for most pitchers.
FIP works for relievers but with more variance due to smaller sample sizes. Over a full season (60+ IP for relievers), FIP is quite reliable. For shorter samples, xFIP may be more stable.