DrawOuts0–60% scaleNext cardBy the river
Pocket pair → set24%8%
Gutshot straight48%16%
Two overcards612%24%
Open-ended straight816%32%
Flush draw918%36%
Flush + gutshot1224%≈45%
Flush + open-ended1530%≈54%
by the turnby the river
Rule of 2 and 4: outs × 2 for the next card; use × 4 against a price only when the call guarantees both cards. Otherwise include implied odds. The shortcut slightly overstates the biggest draws: 12 outs is ≈ 45% and 15 outs ≈ 54% by the river.