Calculate a pitcher's ERA instantly. Enter earned runs, innings, and outs—get accurate results with a quality rating that tells you what the number actually means.

If you've ever tried to calculate ERA by hand and gotten tripped up by partial innings, you're not alone. Is 5.1 innings the same as 5.1? (Spoiler: it's not.) This calculator handles all of that so you can skip the math and get straight to the answer.

Just plug in earned runs, innings pitched, and any extra outs. The calculator does the conversion, applies the formula, and gives you an ERA accurate to two decimal places—exactly how it appears in official stats.

Whether you're a coach building a pitching staff, a fantasy player weighing a trade, or a parent trying to figure out if your kid's 2.35 ERA is actually good, you'll get a clear number and the context to understand it.

ERA stands for Earned Run Average. It answers a simple question: how many runs does this pitcher allow in a typical nine-inning game?

The "earned" part matters. If a runner reaches because your shortstop boots a grounder and later comes around to score, that's on the defense—not the pitcher. ERA only counts runs the pitcher is directly responsible for. It's baseball's way of being fair.

This stat has been around since the early 1900s, and it's stuck for good reason. Wins depend on run support. Strikeouts don't always prevent runs. But ERA cuts to what actually matters: when this pitcher is on the mound, how many runs cross the plate?

That said, ERA isn't perfect. A pitcher on a team with Gold Glove defenders will post a lower ERA than the same pitcher behind a shaky infield. We'll get into those nuances later. But as a starting point for evaluating pitchers, ERA is still the gold standard.

A number without context is just a number. Here's what ERA tells you at the MLB level:

One thing to keep in mind: these benchmarks shift over time. During the offensive explosion of the early 2000s, a 4.50 ERA was respectable. In the strikeout-heavy 2010s, that same number got you designated for assignment. Context always matters.

Here's the math:

ERA = (Earned Runs × 9) ÷ Innings Pitched

Multiply earned runs by 9, divide by innings. That's it. The "times 9" standardizes everything to a nine-inning game, so you can compare a workhorse starter (200+ innings) to a specialist reliever (40 innings) on equal footing.

Say a pitcher has allowed 38 earned runs over 147 innings and 2 outs.

First, convert the innings: 147 innings + 2 outs = 147 + (2÷3) = 147.667 innings

Then, apply the formula: ERA = (38 × 9) ÷ 147.667 ERA = 342 ÷ 147.667 ERA = 2.32

That's excellent—comfortably in the "ace" range at any level.

Here's a quirk that trips people up: when you see 67.2 innings pitched, that's not 67.2 in the mathematical sense. It means 67 innings and 2 outs—or 67⅔ innings.

Baseball uses a weird notation:

• .1 = 1 out recorded = one-third of an inning
• .2 = 2 outs recorded = two-thirds of an inning

So 5.1 IP is actually 5⅓ innings (5.333...), and 5.2 IP is 5⅔ innings (5.667...).

Why does baseball do this? Tradition, mostly. It's been recorded this way for over a century, and nobody's going to change it now.

The good news: this calculator sidesteps the confusion entirely. Enter complete innings in one field, additional outs (0, 1, or 2) in another. No conversion needed on your end.

Enter Earned Runs The total earned runs allowed. Don't include unearned runs—those are on the defense, not the pitcher.

Enter Innings Pitched Complete innings only. If the stat line shows 82.1 IP, enter 82 here.

Enter Outs Pitched Any outs beyond complete innings. For 82.1 IP, enter 1. For a clean 82.0, enter 0.

Read Your Result You'll get an ERA to two decimal places, plus context on what that number means.

What counts as "good" depends entirely on who you're measuring. MLB hitters are the best in the world—a 3.80 ERA against them is solid work. High school hitters? Different story.

College hitters are talented but still developing. Plus, aluminum bats add offense. Expect ERAs slightly lower than MLB but not dramatically so.

Good high school pitchers dominate. The gap between a polished varsity arm and the average high school hitter is significant. If your kid has a 2.00 ERA on varsity, college coaches will notice.

At younger levels, the strike zone shrinks, walks multiply, and one dominant pitcher can carry a team. ERAs tend to be either very low (good pitcher) or very high (still learning). Not much middle ground.

Note on 7-inning games: Some youth and high school leagues play 7-inning games. The standard convention is still to use the 9-inning formula for stat-keeping purposes. This keeps numbers comparable when players move up levels or submit recruiting profiles.

Your team's #1 starter has been dealing all season: 14 earned runs allowed in 78 innings.

• Earned Runs: 14
• Innings Pitched: 78
• Outs Pitched: 0
• ERA: 1.62

That's an elite high school number. If he's got the velocity to match, D1 programs are watching.

You're eyeing a reliever who's been solid: 16 earned runs in 48.2 innings.

• Earned Runs: 16
• Innings Pitched: 48
• Outs Pitched: 2
• ERA: 2.96

Under 3.00 for a reliever? That's well above average. Worth the add in most formats.

Last year's staff ace has struggled coming back from injury: 62 earned runs in 104.1 innings.

• Earned Runs: 62
• Innings Pitched: 104
• Outs Pitched: 1
• ERA: 5.35

That's rough. Below average even by generous standards. He's either still hurt, tipping pitches, or the league has figured him out.

A rookie reliever comes up and dominates: 2 earned runs in 14 innings. His ERA? A sparkling 1.29.

Before you crown him the next Mariano Rivera, remember: 14 innings is nothing. One bad outing—say, 4 runs in an inning—jumps that ERA to 3.60. Small samples lie. Wait for 40+ innings before drawing conclusions.

Two pitchers. Same earned runs. Slightly different innings:

Pitcher A: 28 ER in 91.0 IP = 2.77 ERA Pitcher B: 28 ER in 91.2 IP = 2.75 ERA

Those two extra outs—maybe a clutch strikeout with the bases loaded—separate them on the leaderboard. In a tight ERA race, every out counts. This is why the "outs pitched" field exists.

Before you judge a pitcher solely by ERA, consider what might be helping or hurting that number:

The Ballpark Factor

Coors Field in Denver is a launching pad—fly balls carry in thin air, and ERAs suffer. Oracle Park in San Francisco plays like a pitcher's paradise. Same pitcher, same stuff, different ERA depending on home stadium. Analysts use "ERA+" to adjust for this, but raw ERA doesn't.

The Defense Behind Them

A ground ball pitcher lives and dies with his infield. Put elite defenders behind him, and soft grounders become outs. Put shaky fielders back there, and those same grounders become singles. ERA captures the result, not the cause.

Bullpen Roulette

Here's a frustrating one for starters: if you leave the game with runners on base and the reliever lets them score, those runs count against your ERA. A starter with a lockdown bullpen looks better than one whose relievers keep letting inherited runners score.

Balls Finding Gloves (Or Not)

Sometimes a line drive goes right at someone. Sometimes it splits the gap. Over a full season, this luck tends to even out. Over a month? A pitcher can look much better or worse than he actually is based purely on where balls happen to land.

None of this means ERA is useless—it's still the best quick snapshot of pitcher performance. Just know it's not the whole picture.

ERA works best alongside other metrics. Here's how they fit together:

WHIP (Walks + Hits per Inning Pitched)

WHIP counts baserunners regardless of whether they score. A pitcher with a 3.20 ERA but 1.45 WHIP is putting a lot of traffic on the bases and getting lucky. That ERA is probably headed up. When ERA and WHIP tell different stories, trust WHIP to predict what's coming.

FIP (Fielding Independent Pitching)

FIP estimates what a pitcher's ERA "should" be based only on strikeouts, walks, hit batters, and home runs—outcomes the pitcher controls without fielder involvement. When ERA and FIP diverge significantly, the ERA usually moves toward the FIP over time. Think of FIP as ERA's reality check.

K/9 (Strikeouts per 9 Innings)

Strikeouts are the cleanest outs. No chance for an error, no ball in play to find a hole. Pitchers with high K/9 rates tend to have lower ERAs because they're taking the defense out of the equation.

ERA+ (Adjusted ERA)

ERA+ adjusts for ballpark and league context, then scales to 100 as average. An ERA+ of 120 means the pitcher was 20% better than league average. It's the best way to compare pitchers across different eras and environments.

ERA has been the go-to pitching stat for over a century because it measures what matters most: run prevention. It's not perfect—defense, ballparks, and luck all leave fingerprints on the number. But as a quick read on how a pitcher has performed, nothing beats it.

For coaches tracking developing arms, focus less on the absolute number and more on the trend. A pitcher who drops from 3.80 to 2.90 over a season is clearly improving, regardless of where those numbers fall on the scale. Progress matters more than perfection.

For fantasy players and stat nerds, pair ERA with WHIP and FIP. When all three agree, you're seeing the real pitcher. When they diverge, regression is probably coming.

And for everyone else—parents, fans, players building a stat sheet—this calculator gives you the number and the context to know what it means. That's the whole point.