Baseball ERA Calculator

Calculate a pitcher earned run average, the classic measure of how many earned runs a pitcher gives up per nine innings. The formula is earned runs multiplied by nine, divided by innings pitched. Because a standard game is nine innings, multiplying by nine scales the rate to a full game so you can compare a starter and a reliever fairly. Enter the earned runs a pitcher allowed and the innings pitched, and note that a partial inning is counted in thirds: one out is 0.1, two outs is 0.2, so two and a third innings is entered as 2.1. The tool converts that notation to true thirds before dividing, then rounds the ERA to two decimals. A lower ERA is better, and elite starters often sit under three. Everything runs locally in your browser.