FIP Calculator
Enter a pitcher's home runs allowed, walks, hit batters, strikeouts, and innings pitched to calculate their Fielding Independent Pitching (FIP). FIP isolates the outcomes a pitcher controls directly, stripping out defense and luck. You also get xFIP, which normalises the home-run rate to the league average so you can compare pitchers across different home-run environments. The FIP constant can be set manually or derived from league-wide totals.
Formula
Worked example
A pitcher with 15 HR, 30 BB, 4 HBP, 2 IBB, 150 K, and 150 IP: effective walks = 30 - 2 + 4 = 32. Numerator = (13 × 15) + (3 × 32) - (2 × 150) = 195 + 96 - 300 = -9. FIP = -9 / 150 + 3.17 = -0.06 + 3.17 = 3.11, which is excellent. If the pitcher also allowed 145 fly balls, xFIP = (13 × 15.225 + 96 - 300) / 150 + 3.17 = 3.13.
What is FIP?
Fielding Independent Pitching (FIP) is an advanced baseball statistic designed to measure pitcher performance using only outcomes the pitcher directly controls: home runs, walks, hit batters, and strikeouts. It strips out everything that depends on fielding quality or batted-ball luck, so it reflects how well a pitcher actually pitched rather than how many runs scored while they were on the mound. FIP was popularised by sabermetrics researcher Tom Tango and is now a standard part of the stat lines published on FanGraphs and used widely by MLB front offices.
Why FIP is more predictive than ERA
Earned Run Average (ERA) captures every run that scores in a pitcher's starts, including those due to poor fielding, bad defensive positioning, or random variation in where balls land. Research consistently shows that pitchers have little control over batting average on balls in play (BABIP) from year to year - that number drifts toward a league-average around .300 for most pitchers regardless of their skill. FIP bypasses that noise by weighting only the events the pitcher truly determines: strikeouts (which give no opportunity to field the ball), home runs (which always score), and walks and hit batters (which load bases regardless of defense). As a result, FIP tends to predict future ERA better than current ERA does, especially over smaller sample sizes.
xFIP and normalising home-run rate
Even home runs contain a component of luck and park effects. xFIP (Expected FIP) takes the analysis a step further by replacing actual home runs with an expected total based on the pitcher's fly-ball rate and the historical league-average HR-per-fly-ball rate of roughly 10.5%. This removes park factor and short-term variance in HR/FB rate, producing an even more stabilised estimate of true pitching skill. When xFIP is significantly lower than FIP, the pitcher likely benefited from an above-average HR/FB rate that is unlikely to continue. When xFIP is higher, the pitcher was suppressing home runs at an unsustainable rate and FIP may deteriorate.
How to use the FIP constant
The FIP constant C is added to place FIP on the same numeric scale as ERA, so a league-average FIP equals the league-average ERA. For recent MLB seasons the constant has hovered around 3.10-3.20; FanGraphs publishes the exact value each season. If you are evaluating a specific MLB season, enter the published constant for that year. If you are calculating FIP for a non-MLB league - college, independent, international - use the "derive from league totals" mode and enter the full-season league statistics to compute an appropriate constant for that context. The calculator will work out the constant automatically from league ERA and league-wide pitcher totals.
K/9, BB/9, and HR/9: the building blocks
The three rate statistics shown alongside FIP reveal the underlying drivers. K/9 (strikeouts per 9 innings) measures a pitcher's ability to miss bats - the primary way to avoid damage. MLB average K/9 has risen steadily and now sits around 8.5; elite strikeout artists post 11 or higher. BB/9 (walks and hit batters per 9 innings) measures control; below 2.5 is excellent, above 4.0 is a red flag. HR/9 measures fly-ball vulnerability adjusted for volume; below 1.0 is very good, and 1.5 or above is a significant problem. Improving any of these three inputs will directly lower FIP, but because home runs carry a weight of 13 in the formula - more than four times the weight of a walk - suppressing them yields the largest return.
FIP performance scale (MLB context)
| FIP range | Rating | MLB equivalent |
|---|---|---|
| Below 3.00 | Elite / ace | Top 5-10% of starters |
| 3.00-3.49 | Excellent | Top 15-20% of starters |
| 3.50-3.99 | Above average | Solid no. 2 or no. 3 starter |
| 4.00-4.49 | Average | League-average pitcher |
| 4.50-4.99 | Below average | Back-end rotation or setup reliever |
| 5.00 and above | Poor | Replacement-level or worse |
Based on FanGraphs pitching value tiers. FIP is calibrated to the ERA scale, so league-average FIP equals league-average ERA (~4.0-4.1 in recent MLB seasons.
Frequently asked questions
What is a good FIP in baseball?
Because FIP is calibrated to the ERA scale, the same rough thresholds apply: below 3.00 is elite or ace-level, 3.00-3.49 is excellent, 3.50-3.99 is above average, 4.00-4.49 is average (close to the league mean), 4.50-4.99 is below average, and 5.00 or higher is poor or replacement-level. These benchmarks shift slightly from year to year depending on the run-scoring environment, but they are a reliable starting point for any modern MLB season.
How is FIP different from ERA?
ERA includes every earned run that scores while a pitcher is responsible, regardless of whether poor fielding, unlucky ball placement, or variance in batted-ball outcomes contributed. FIP ignores all batted balls and counts only the three outcomes most tightly under a pitcher's control: strikeouts (weight -2), walks and hit batters (weight +3), and home runs (weight +13). The result is a number that predicts future performance better than ERA does, especially in samples of fewer than 100 innings.
Why are intentional walks subtracted from the FIP formula?
Intentional walks (IBB) are a deliberate managerial decision, not a sign of a pitcher losing control or missing the strike zone. Including them would penalise pitchers for a tactic used strategically to avoid dangerous hitters. Most modern FIP implementations subtract IBB from total walks before applying the formula, so the walk term reflects only unintentional free passes.
What does xFIP tell me that FIP does not?
FIP uses actual home runs, which can fluctuate year to year even for pitchers with similar underlying skills - partly because of ballpark dimensions and partly because the fraction of fly balls that leave the park varies somewhat randomly. xFIP replaces actual home runs with an expected home-run total calculated by multiplying fly balls by the long-run MLB average HR/FB rate (~10.5%). This makes xFIP more stable than FIP as a forward-looking indicator: a pitcher whose FIP is much lower than their xFIP likely benefited from a lucky HR/FB rate that will normalise.
What is the FIP constant and where do I find it?
The FIP constant is a scaling factor added to raw FIP so that the league average FIP equals the league average ERA for that season. It changes slightly from year to year with the run environment. FanGraphs publishes the exact MLB constant for each season - search "FanGraphs FIP constant [year]". For recent MLB seasons it has been approximately 3.10-3.20. If you are computing FIP for a non-MLB league, use our "derive from league totals" mode and enter the full-season league stats.
Can FIP be used for relievers as well as starters?
Yes. FIP is calculated the same way for both. However, relievers tend to have more volatile FIP because they pitch fewer innings, giving smaller samples. A reliever with 25 innings and a great FIP has far less certainty around that number than a starter with 180 innings. For relievers, it is often better to look at multi-year FIP or use FIP alongside other indicators like swinging-strike rate.
Is a lower FIP always better?
Yes - like ERA, a lower FIP means fewer runs per 9 innings in expectation. There is no scenario where a higher FIP represents better pitching performance. The statistic is built so that a pitcher at 2.80 clearly outperforms one at 4.80, all else equal.