Sports & Gaming · Statistics · Descriptive Statistics
Fielding Independent Pitching (FIP) Calculator
Calculates FIP, a pitching metric that isolates a pitcher's performance on outcomes they directly control: home runs, walks, hit batsmen, and strikeouts.
Calculator
Formula
HR = home runs allowed; BB = walks (bases on balls); HBP = hit batters; K = strikeouts; IP = innings pitched; C_FIP = FIP constant (typically ~3.10, scaled so league FIP equals league ERA).
Source: Voros McCracken (2001), popularized by Tom Tango; FIP constant methodology described at FanGraphs Library (https://library.fangraphs.com/pitching/fip/).
How it works
FIP is computed from four components multiplied by empirically derived weights: home runs allowed (multiplied by 13), walks plus hit batters (multiplied by 3), and strikeouts (multiplied by 2, subtracted). This weighted sum is divided by innings pitched and then a league-specific FIP constant is added. The constant is calibrated each season so that the average FIP equals the average ERA across all qualified pitchers, making FIP directly comparable to ERA on the same scale.
The weights (13, 3, and 2) reflect the run values of each event relative to an average plate appearance outcome. Home runs are the most damaging event a pitcher can surrender, walks and hit batters put runners on base without a fielder touching the ball, and strikeouts are the best outcome a pitcher can achieve. Because the FIP constant is re-computed annually by leagues and statistical aggregators like FanGraphs, using the current season's constant (~3.10 for recent MLB seasons) ensures meaningful comparisons to ERA.
FIP is widely used in player valuation, arbitration, contract negotiations, and Cy Young Award discussions. It is particularly valuable for identifying pitchers whose ERA overestimates or underestimates their true performance due to above- or below-average fielding behind them, or clusters of hits that regression to the mean would predict to normalize.
Worked example
Example: Evaluating a Starting Pitcher's Season
Suppose a pitcher finishes a season with the following line: 180 IP, 15 HR, 40 BB, 5 HBP, 180 K, and we use a FIP constant of 3.10.
Step 1 — Numerator:
(13 × 15) + (3 × (40 + 5)) − (2 × 180)
= 195 + 135 − 360
= −30
Step 2 — Divide by IP:
−30 ÷ 180 = −0.167
Step 3 — Add the FIP constant:
−0.167 + 3.10 = 2.93
A FIP of 2.93 is excellent — well below the league-average ~4.00 — indicating this pitcher dominated opposing hitters on the outcomes he directly controlled. This would place him among the top pitchers in the league for the season.
Limitations & notes
FIP does not account for all pitching skill. Sequencing ability — how a pitcher performs with runners on base — is intentionally excluded. Some pitchers may consistently post ERAs lower than their FIP (indicating genuine ability to strand runners, suppress BABIP on soft contact, or induce weak contact), while others may outperform their FIP in small samples due to luck. FIP also does not differentiate between a walk and an intentional walk, nor does it capture the quality of contact allowed on balls in play. For a fuller picture, analysts often consult xFIP (which normalizes HR/FB rate), SIERA (which incorporates batted ball data), or other advanced metrics alongside FIP. The FIP constant must match the season and league being analyzed; using a wrong constant will shift all FIP values systematically and make comparisons to ERA invalid.
Frequently asked questions
What is a good FIP for a starting pitcher?
FIP is scaled to ERA, so the same benchmarks apply: below 3.00 is excellent (top-tier ace level), 3.00–3.75 is above average, 3.75–4.50 is average, 4.50–5.25 is below average, and above 5.25 indicates significant struggles. The league-average FIP is typically between 3.90 and 4.20 in modern MLB.
Why does FIP use the specific weights 13, 3, and 2?
These weights are derived from linear weights — the empirical run values of each event relative to an average outcome. Home runs are worth approximately 1.4 runs each on average, making the coefficient 13 after scaling. Walks and hit batters are worth roughly 0.33 runs, giving a coefficient of 3. Strikeouts prevent approximately 0.2 runs, giving a subtracted coefficient of 2. The scaling ensures FIP sits on the ERA scale when the constant is added.
What is the FIP constant and how do I find the current value?
The FIP constant (C_FIP) is computed each season by taking the league ERA minus the league raw FIP component (the weighted numerator divided by total IP). This ensures that the average FIP across all pitchers equals the average ERA. FanGraphs publishes the annual FIP constant for MLB; for recent seasons it has been approximately 3.10. For minor leagues or other organizations, you would need to compute it from league-wide totals.
How does FIP differ from xFIP and SIERA?
FIP uses actual home runs allowed. xFIP (Expected FIP) replaces actual HR with an expected HR based on fly ball rate multiplied by a league-average HR/FB rate (~10.5%), which helps neutralize park effects and small-sample HR variation. SIERA (Skill-Interactive ERA) is more complex, incorporating ground ball rate, fly ball rate, and strikeout rate to better model how batted ball profile interacts with run prevention. FIP is the simplest and most transparent of the three.
Can FIP be used for relief pitchers?
Yes, FIP can be calculated for any pitcher with at least some innings pitched, including relievers. However, small sample sizes make FIP highly variable for pitchers with fewer than 20–30 innings. Additionally, reliever FIP should be compared to other reliever FIPs rather than to starters, since the conditions differ (e.g., leverage index, batter handedness matchups). Many analysts use rolling FIP over multiple seasons or leverage-adjusted metrics for bullpen evaluation.
Does a lower FIP always mean a pitcher is better than his ERA suggests?
Not necessarily. If a pitcher's FIP is significantly lower than his ERA, it often suggests his defense was poor or he was unlucky with BABIP. However, some pitchers consistently outperform their FIP (post lower ERAs) due to skills not captured by FIP — such as exceptional deception, elite pitch sequencing, or an ability to induce weak contact. Persistent ERA-FIP gaps over many seasons are worth investigating beyond the metric itself.
Last updated: 2025-01-30 · Formula verified against primary sources.