Flush Draw

Also known as: flushdraw, four to a flush, fd, four-flush

Four cards to a flush — 9 outs, roughly 19.6% per street and about 35% from flop to river.

A flush draw is four cards of one suit needing a fifth. With 13 cards per suit and 4 in view, 9 outs remain.

With the Rule of 2 and 4:

• Per street: \(9 \times 2 = 18\%\). Exact: \(\dfrac{9}{47} \approx 19.6\%\).
• Flop to river (two cards): \(9 \times 4 = 36\%\). Exact: about \(35\%\) — the standard "35% by the river" figure.

Nine outs makes the flush draw the workhorse semi-bluff. It carries enough equity to check-raise, float, double-barrel, and bet/3-bet on the flop, and it pairs naturally with straight draws to form 12–15-out combo draws.

Not all flush draws are equal:

• A nut flush draw carries strong implied odds and is itself a powerful blocker — holding the ace of the suit removes the opponent's nut flush.
• A low flush draw suffers reverse implied odds: you can complete and still lose to a higher flush.

On the river a completed third-suit card also matters for the non-flush hands — it caps ranges and changes who can credibly represent the nuts.