Baseball Advanced Stats Calculator (FIP, WHIP, ERA+)

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. Below 2.50 is ace territory. 2.50–3.00: elite. 3.00–3.75: above average. 3.75–4.50: average. 4.50–5.50: below average. Above 5.50: struggling. Those are the exact bands the calculator grades against, and it grades ERA on the same ladder so the two read side by side.

WHIP: Walks plus Hits per Inning Pitched WHIP = (Walks + Hits) / Innings Pitched Below 0.90 is elite, and fewer than one baserunner an inning is the line most people know. 0.90–1.10: excellent, typical of a front-of-rotation starter. 1.10–1.25: above average. 1.25–1.40: league average. 1.40–1.60: below average. Above 1.60: poor.

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 Above 10.5 is elite in modern MLB. 9.0–10.5: excellent. 7.5–9.0: good. 6.0–7.5: average. Below 6.0 is low. Strikeout rates have risen dramatically in MLB: from ~5 K/9 league average in 1990 to ~8.5 K/9 by 2023, which is why those bands sit higher than the ones you will find in an older reference.

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.

A note on innings pitched. Innings are counted in outs, so they are written .0, .1 and .2 and never anything higher. 180.2 is 180 and two thirds, not 180 point two. Every rate on this page divides by that figure, so entering 180.9 because a spreadsheet gave you a decimal would put you two innings out before the first calculation. The calculator refuses anything above .2 rather than converting it silently.

This page is all pitching. For a hitter’s line, batting average, on-base percentage, slugging and OPS, use the baseball stats calculator.