What are the odds of a backdoor flush?
A backdoor flush draw (three to a flush on the flop) gets there 4.16% of the time — it needs both the turn and the river.
Three to a flush on the flop needs two more of the suit in a row. Ten remain, so the turn hits 10/47 of the time and the river then 9/46 — about 4.2% overall, or 1 in 24.
On its own that is almost nothing, but backdoor draws add a few percent of equity to hands that already have something else — which is why they matter in close decisions.
- Suited cards unseen1013 − 3
- Turn is the suit21.28%10 / 47
- River is the suit, given the turn was19.57%9 / 46
- Both4.16%10/47 × 9/46
Try it
Change any card; the numbers recompute from the same engine that produced the answer above.
You get there about 1 time in 4 by the river.
The 6 highlighted cards are your outs.
What you’re drawing to
- Backdoor flush draw4.16%
Needs both the turn and the river: 10/47 × 9/46.
- One overcard3 outs
Pairing an overcard makes top pair, which is not always the best hand.
Shortcut vs. exact
| Cards to come | Rule of 2/4 | Exact | Gap |
|---|---|---|---|
| Turn only | 12% | 12.77% | −0.77 pts |
| Turn and river | 24% | 24.14% | −0.14 pts |