What Are the Odds of Four to a Flush on the Board?
The board shows four or more cards of one suit about 4.49% of the time — 1 in 22 — which is why a single suited card in your hand can suddenly matter so much by the river.
The odds
| Measured as | Probability | Odds | Per 100 hands |
|---|---|---|---|
| Four or more of one suit on the board by the riverheadline | 4.49% | 1 in 22 | 4.5 |
| All five board cards one suit (monotone) | 0.198% | 1 in 505 | — |
What we measured
This counts boards where at least four of the five community cards share a suit (four-flush or a fully monotone five-flush board). On such a board, any player holding one card of that suit makes a flush, and it is often the highest suited card that wins.
How it was calculated
Exact combinatorics: four-of-a-suit boards (4 x C(13,4) x 39) plus five-of-a-suit boards (4 x C(13,5)), over C(52,5) = 2,598,960.
Computed 2026-07-12 using app/lib/poker-eval.js — the same 7-card evaluator behind /tools/odds-calculator. Want to test a specific matchup? Run it through the odds & equity calculator.
The board shows four or more cards of one suit about 4.49% of the time — 1 in 22 — which is why a single suited card in your hand can suddenly matter so much by the river.
https://pokerpro.tools/odds/four-flush-boardDrop it in your poker chat, home-game thread, or the next bad-beat argument.
Frequently asked questions
How often does the board have four of the same suit?+
About 4.49% of hands — 1 in 22 — the five community cards include at least four of one suit. A fully monotone five-suited board is much rarer, about 1 in 505.
What happens when four to a flush is on the board?+
Anyone with a single card of that suit makes a flush, so hands cheapen fast — the player with the highest suited card wins, and if nobody holds one, the board's own flush plays and the pot chops.