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ERA Calculator

Walks per nine

BB/9 Calculator

Calculate walks per nine innings from walks and innings pitched. Accurate baseball innings notation included.

BB/9

BB/9 2.57. 10 walks over 35 innings.

Outs recorded in the final inning

Baseball notation works too: type 6.1 for 6⅓ or 6.2 for 6⅔ innings.

How this result was calculated

  • BB/9 = 10 × 27 ÷ 105 outs = 2.57
  • (10 × 9 ÷ 35 innings)

Meaning

What is BB/9?

BB/9 is walks allowed per nine innings. It answers how many free passes a pitcher issues over a full game at their current rate, independent of how many strikeouts or hits they allow.

Lower is better. Major-league starters often aim under about 3.0 BB/9; walk rates above 4.0 start putting constant pressure on ERA, WHIP and FIP.

Formula

The formula

BB/9 = (Walks × 9) ÷ Innings Pitched

Same outs form as other rate stats: BB/9 = walks × 27 ÷ outs. Intentional walks usually count in BB totals the same way official stats do.

Partial innings (.1 / .2) are converted to outs before the divide.

How to calculate

Step by step

  1. Total walks allowed.
  2. Convert innings pitched to outs.
  3. Multiply walks by 27 and divide by outs.
  4. Round to two decimal places.

Worked example

25 walks in 82.0 innings is 25 × 9 ÷ 82 ≈ 2.74 BB/9. In outs: 25 × 27 ÷ 246 ≈ 2.74.

Related

BB/9 vs WHIP and K/BB

WHIP mixes walks with hits. BB/9 isolates the walk rate alone. K/BB compares strikeouts to walks as a ratio. A pitcher can have a fine K/9 and still hurt their WHIP and FIP with a high BB/9.

Pair walk rate with K/9 Calculator.

Or combine both sides in the K/BB Ratio Calculator.

FAQ

Common questions

How do you calculate BB/9?

Multiply walks by 9 and divide by innings pitched, or use BB/9 = walks × 27 ÷ outs for partial innings.

What is a good BB/9?

Under roughly 2.5–3.0 is strong in MLB; around 3.5 is closer to average depending on the season. High-walk power pitchers sometimes survive with huge strikeout rates, but walks still tax every other metric.

Do intentional walks count in BB/9?

Yes — official walk totals include intentional walks, and this calculator uses the walk count you enter the same way.

How do walks affect ERA and FIP?

Walks put runners on base (hurting WHIP and often ERA) and are weighted positively in the FIP formula, so a high BB/9 pushes FIP up even when the defense is perfect.

Related

Related pitching calculators

Stack BB/9 with K/9, K/BB, WHIP and FIP to see how free passes shape the rest of the line.

Baseball Pitching Calculators →