​
​
Sign In
  • Support FanGraphs
    FanGraphs Membership
    FanGraphs Shirts
    FanGraphs Mugs
    Gift a Membership
    Donate to FanGraphs
  • Fantasy
    Fantasy Tools
    Fantasy Player Rater
    Auction Calculator
    Ottoneu Fantasy Baseball
    Signup, FAQ, Blog Posts
  • Blogs
    Blog Roll

    FanGraphs
      Podcasts: Effectively Wild

      FanGraphs Prospects

      RotoGraphs
        Podcasts: The Sleeper and The Bust | Field of Streams | Beat the Shift

        Community Research

          Archived Blogs: The Hardball Times | NotGraphs | TechGraphs | FanGraphs+
          Archived THT: THT Live | Dispatch | Fantasy | ShysterBall
          Archived Podcasts: FanGraphs Audio | Chin Music | UMP: The Untitled McDongenhagen Project | Stealing Home | Doing It For Bartolo | OttoGraphs |
        • Projections
          2025 Pre-Season Projections
          ZiPS, ZiPS DC
          Steamer
          Depth Charts
          ATC
          THE BAT, THE BAT X
          OOPSY
          2025 600 PA / 200 IP Projections
          Steamer600, Steamer600 (Update)
          2025 Updated In-Season Projections
          ZiPS (RoS), ZiPS (Update), ZiPS DC (RoS)
          Steamer (RoS), Steamer (Update)
          Depth Charts (RoS)
          ATC DC (RoS)
          THE BAT (RoS), THE BAT X (RoS)
          OOPSY DC (RoS)
          3-Year Projections
          ZiPS 2026, ZiPS 2027
          On-Pace Leaders
          Every Game Played, Games Played %
          Cy Young Award Projections

          Auction Calculator
        • Scores
          Today
          Live Scoreboard, Probable Pitchers
          Live Daily Leaderboards
          Win Probability & Box Scores
          2025, 2024, 2023, 2022, 2021, 2020, 2019
          AL Games
          NL Games
        • Standings
          2025 Projected Standings
          2025 Playoff Odds, Playoff Odds Graphs
          2024 ZiPS Postseason Game-By-Game Odds
          AL East
          AL Central
          AL West
          NL East
          NL Central
          NL West
        • Leaders
          Major League Leaders
          Batting: 2025, 2024, 2023, 2022, 2021, Career
          Pitching: 2025, 2024, 2023, 2022, 2021, Career
          Fielding: 2025, 2024, 2023, 2022, 2021, Career
          Major League Leaders - Rank
          Batting: Ranking Grid, Compare Players, Compare Stats
          Pitching: Ranking Grid, Compare Players, Compare Stats
          Splits Leaderboards
          Season Stat Grid

          Postseason Leaders
          Batting: 2024, (WS), (LCS), (LDS), (WCS), Career
          Pitching: 2024, (WS), (LCS), (LDS), (WCS), Career

          Spring Training Leaders
          Batting: 2025, 2024, 2023
          Pitching: 2025, 2024, 2023

          KBO Leaders
          Batting, Pitching
          NPB Leaders
          Batting, Pitching

          Minor League Leaders
          AAA: International League, Pacific Coast League
          AA: Eastern League, Southern League, Texas League
          A+: Midwest League, South Atlantic League, Northwest League
          A: California League, Carolina League, Florida State League
          CPX: Arizona, Florida
          R: Dominican Summer League
          College Leaders
          Batting, Pitching

          WAR Tools
          Combined WAR Leaderboards
          WAR Graphs
          WPA Tools
          WPA Inquirer
          Rookie Leaders
          Batters 2025, Pitchers 2025
          Splits Leaders
          Batters: vs L, vs R, Home, Away
          Pitchers: vs L, vs R, Home, Away
        • Teams
          Team Batting Stats
          2025, 2024, 2023, 2022, 2021, 2020
          Team Pitching Stats
          2025, 2024, 2023, 2022, 2021, 2020
          Team WAR Totals (RoS)
          AL East
          Blue Jays  |  DC
          Orioles  |  DC
          Rays  |  DC
          Red Sox  |  DC
          Yankees  |  DC
          AL Central
          Guardians  |  DC
          Royals  |  DC
          Tigers  |  DC
          Twins  |  DC
          White Sox  |  DC
          AL West
          Angels  |  DC
          Astros  |  DC
          Athletics  |  DC
          Mariners  |  DC
          Rangers  |  DC
          NL East
          Braves  |  DC
          Marlins  |  DC
          Mets  |  DC
          Nationals  |  DC
          Phillies  |  DC
          NL Central
          Brewers  |  DC
          Cardinals  |  DC
          Cubs  |  DC
          Pirates  |  DC
          Reds  |  DC
          NL West
          D-backs  |  DC
          Dodgers  |  DC
          Giants  |  DC
          Padres  |  DC
          Rockies  |  DC
          Positional Depth Charts
          Batters: C, 1B, 2B, SS, 3B, LF, CF, RF, DH
          Pitchers: SP, RP
        • RosterResource
          Current Depth Charts
          AL East
          Blue Jays
          Orioles
          Rays
          Red Sox
          Yankees
          AL Central
          Guardians
          Royals
          Tigers
          Twins
          White Sox
          AL West
          Angels
          Astros
          Athletics
          Mariners
          Rangers
          NL East
          Braves
          Marlins
          Mets
          Nationals
          Phillies
          NL Central
          Brewers
          Cardinals
          Cubs
          Pirates
          Reds
          NL West
          D-backs
          Dodgers
          Giants
          Padres
          Rockies
          In-Season Tools
          2025 Closer Depth Chart
          2025 Injury Report
          2025 Payroll Pages
          2025 Transaction Tracker
          2025 Schedule Grid
          2025 Probables Grid
          2025 Lineup Tracker
          2025 Minor League Power Rankings
          Offseason Tools
          2025 Free Agent Tracker
          2025 Offseason Tracker
          2025 Opening Day Tracker
        • Prospects
          Prospects Home
          The Board
          The Board: Scouting + Stats!
          How To Use The Board: A Tutorial
          Farm System Rankings

          Top Prospects List
          20252024
          AL
          BALCHWATH
          BOSCLEHOU
          NYYDETLAA
          TBRKCRSEA
          TORMINTEX
          NL
          ATLCHCARI
          MIACINCOL
          NYMMILLAD
          PHIPITSDP
          WSNSTLSFG
          2025 Preseason Top 100
        • Glossary
          Library
          Batting Stats
          wOBA, wRC+, ISO, K% & BB%, more...
          Pitching Stats
          FIP, xFIP, BABIP, K/9 & BB/9, more...
          Defensive Stats
          UZR Primer, DRS, FSR, TZ & TZL, more...
          More
          WAR, UBR Primer, WPA, LI, Clutch
          Guts!
          Seasonal Constants
          Park Factors
          Park Factors by Handedness
        • Sign In
        • Intro
        • Features
        • Offense
          • Complete List (Offense)
          • OBP
          • OPS and OPS+
          • wOBA
          • wRC and wRC+
          • wRAA
          • Off
          • BsR
          • UBR
          • wSB
          • wGDP
          • BABIP
          • ISO
          • HR/FB
          • Spd
          • Pull%/Cent%/Oppo%
          • Soft%/Med%/Hard%
          • GB%, LD%, FB%
          • K% and BB%
          • Plate Discipline (O-Swing%, Z-Swing%, etc.)
          • Pitch Type Linear Weights
          • Pace
        • Defense
          • Overview
          • Def
          • UZR
          • DRS
          • Defensive Runs Saved – 2020 Update
          • Inside Edge Fielding
          • Catcher Defense
          • FSR
          • RZR
          • TZ / TZL
        • Pitching
          • Complete List (Pitching)
          • PitchingBot Pitch Modeling Primer
          • Stuff+, Location+, and Pitching+ Primer
          • ERA
          • WHIP
          • FIP
          • xFIP
          • SIERA
          • Strikeout and Walk Rates
          • Pull%/Cent%/Oppo%
          • Soft%/Med%/Hard%
          • GB%, LD%, FB%
          • BABIP
          • HR/FB
          • LOB%
          • Pitch Type Linear Weights
          • SD / MD
          • ERA- / FIP- / xFIP-
          • Plate Discipline (O-Swing%, Z-Swing%, etc.)
          • Pace
          • PITCHF/x
            • What is PITCHF/x?
            • Pitch Type Abbreviations & Classifications
            • Heat Maps
            • Common Mistakes
            • PITCHf/x Resources
        • WE/RE/LI
          • RE24
          • Win Expectancy
          • WPA
          • LI
          • WPA/LI
          • Clutch
        • Principles
          • DIPS
          • Regression toward the Mean
          • Replacement Level
          • Sample Size
          • Splits
          • Projection Systems
          • Linear Weights
          • Counting vs. Rate Statistics
          • Park Factors
          • Park Factors – 5 Year Regressed
          • Positional Adjustment
          • Aging Curve
          • League Equivalencies
          • Pythagorean Win-Loss
          • Luck
        • WAR
          • What is WAR?
          • WAR for Position Players
          • WAR for Pitchers
          • FDP
          • fWAR, rWAR, and WARP
          • WAR Misconceptions
        • Business

        ERA

        by Piper Slowinski
        February 16, 2010

        Earned Run Average (ERA) is a rudimentary metric designed to assess how well a pitcher has prevented runs in the past. Given that a pitcher’s job is to aid in the prevention of run scoring, ERA is understandably a popular and widely used statistic. ERA is perhaps the most commonly cited pitching statistic at large, but has a number of serious flaws that should lead you to use it sparingly.

        Calculation:

        To calculate ERA, divide a pitcher’s total number of Earned Runs allowed by his total number of Innings Pitched and multiply by nine.

        ERA = (Earned Runs / Innings Pitched) * 9

        An earned run is essentially any run that was charged to the pitcher which did not score as the result of an error by the defense. The precise definition of how the official scorer makes the distinction can be found here. There are no further adjustments to ERA to account for park or league effects.

        Why ERA:

        ERA is popular because it seems to be answering a very important question. We want to know how many runs the pitcher gave up that were his fault, but unfortunately, despite the name, ERA does not properly answer that question. Simply put, the distinction between unearned and earned runs is not an accurate demarcation between the runs that were the pitcher’s fault and the runs that were not his fault. There are two main reasons for this.

        First, the official scorer determines if something was an error or not and official scorers do not hand out errors consistently, meaning that the same botched play might be scored an error one day and a hit another. Second, and more importantly, bad defense occurs in forms beyond rule book errors.

        If a fielder is chasing down a fly ball and trips right before he’s about to catch it, that is not an error in the eyes of the league and the official scorer even though it was a routine fly ball that he obviously should have caught. The defense can fail the pitcher by making an error and the defense can fail the pitcher by not making a relatively easy play. Neither is the pitcher’s fault, but only error-induced runs are stripped out of ERA.

        In other words, the goal of ERA is perfect but the execution is horrible. We want a statistic that attempts to strip defense out of the equation, but ERA only “strips out” a very small subset of bad defensive plays, leaving pitcher’s who throw in front of base defenses unfairly dinged by ERA. Fielding Independent Pitching (FIP), provides a better approach to the question ERA wants to answer, and Runs Allowed Per 9 (RA9) provides a more useful measure if you are after a statistic that tells you “exactly what happened.”

        How To Use ERA:

        ERA is rarely a statistic you should use on its own because it is highly dependent on defense, luck, and sequencing, and therefore tells you very little useful information about a pitcher. It is perfectly fine to hold a pitcher accountable for his luck and sequencing, and if you want to do that, RA9 is a better statistic to use. If you want to strip out defense, then something like FIP is highly preferable.

        However, if used in conjunction with other metrics like FIP, xFIP, RA9, etc, then you can learn something about the season the pitcher is having. For example, a pitcher with a large ERA-FIP gap probably plays in front of a very good or very bad defense and a pitcher with a large ERA-RA9 gap is likely being victimized by errors quite often.

        ERA is useful because it’s popular and easy to find, but other than convenience, there’s really no reason you would want to know about ERA rather than either RA9 or FIP, depending on your question or philosophical leanings.

        Also, because ERA is highly dependent on non-pitcher factors like defense, umpiring, the scorer, luck, sequencing, etc, it is also not highly predictive of future performance because those factors are not part of the pitcher’s talent level, and therefore, do not often travel with him from season to season.

        Context:

        Please note that the following chart is meant as an estimate, and that league-average ERA varies widely on a year-by-year basis. To see the league-average ERA for every year from 1901 to the present, check the FanGraphs leaderboards. Also note that ERAs are lower for relievers on average than starters. As a rule subtract 0.50 runs from the chart below for relievers.

        Rating ERA
        Excellent 2.50
        Great 3.00
        Above Average 3.40
        Average 3.75
        Below Average 4.00
        Poor 4.30
        Awful 4.60

        Things to Remember:

        ● ERA is difficult to compare across teams due to differences in team defenses, difficult to compare across leagues due to competition imbalance and the DH, and difficult to compare across years because of different run-scoring environments. A 3.50 ERA has a different meaning depending on if that pitcher played in the early 2000s or the Dead Ball Era, or if they played in a pitcher’s or hitter’s park.

        ● To adjust for park and league effects, check out ERA-. It’s still not a perfect statistic, but it does make it easier to compare pitchers from different time periods and parks, but it contains the same general flaws of standard ERA.

        ● Despite the fact that ERA makes an attempt to remove runs that weren’t the pitcher’s fault, it does so in a very haphazard way that does not control for the quality of a pitcher’s defense.

        ● Some people will support ERA as a measure of “what actually happened,” but that is not accurate. If that is your goal, RA9 is a superior stat.

        Links for Further Reading:

        The Most Convoluted Statistic – FanGraphs

        Clayton Kershaw’s ERA – FanGraphs

        The End of ERA – Beyond The Box Score




        wRAA
         
        OBP

        Piper was the editor-in-chief of DRaysBay and the keeper of the FanGraphs Library.

        Subscribe
        Login
        Notify of
        Please login to comment
        3 Comments
        Oldest
        Newest Most Voted
        Inline Feedbacks
        View all comments
        ejhekk33
        13 years ago

        Well, an ERA of 4.50 might not be too bad… For example, look at this pitching line of Madison Bumgarner on May 13, 2011.
        6 IP, 5 H, 3 ER, 2 BB, 6 K

        That’s counted as a quality start. He did earn the loss that day, but his good pitching overall would make me believe in him more.

        If I had a pitcher who had that pitching line every day, even with a 4.50 ERA, he’d be a #2 starter. Possibly #1.

        1
        John C
        12 years ago

        ^ That’s just plain stupid. A 4.50 ERA is NOT good. A quality start is really 6 innings 2 runs, or really 7 innings and 2 runs. If an “ace” pitched 33 quality starts according to this obsurd 3 run standard, then this pitcher would by no means be an ace.
        Going 6 innings everyday would force you to go to your middle relief, set-up man, and closer on a daily basis, thus depleting the bullpen. People really need to stop with this idiotic notion of the 3-run “quality” start and see reality.

        0
        Fascist
        4 years ago

        3 (2018-2020)

        0
        You are going to send email to

        Move Comment

        Updated: Saturday, May 10, 2025 11:35 PM ETUpdated: 5/10/2025 11:35 PM ET
        @fangraphs - Contact Us - Advertise - Terms of Service - Privacy Policy
        sis_logo
        All major league baseball data including pitch type, velocity, batted ball location, and play-by-play data provided by Sports Info Solutions.
        mlb logo
        Major League and Minor League Baseball data provided by Major League Baseball.
        Mitchel Lichtman
        All UZR (ultimate zone rating) calculations are provided courtesy of Mitchel Lichtman.
        TangoTiger.com
        All Win Expectancy, Leverage Index, Run Expectancy, and Fans Scouting Report data licenced from TangoTiger.com
        Retrosheet.org
        Play-by-play data prior to 2002 was obtained free of charge from and is copyrighted by Retrosheet.