Poker Outs Odds Calculator (Texas Hold'em)

From your seat, the 'unseen' cards are the full 52-card deck minus your 2 hole cards and whatever's already on the board — 47 unseen right after the flop (with 2 cards still to come), or 46 unseen after the turn (with 1 card still to come, the river). If 'outs' of those unseen cards complete your hand, the exact probability of hitting at least one of them follows from the hypergeometric distribution (drawing without replacement): outs ÷ unseen with one card to come, or 1 − C(unseen−outs, 2) ÷ C(unseen, 2) with two cards to come (one minus the chance both remaining cards miss every out).

The 'rule of 4 and 2' is the mental-math shortcut experienced players use at the table instead of that combinatorics: multiply your outs by 4 on the flop for a quick estimate of hitting by the river, or by 2 on the turn for hitting on the very next card. It's a close approximation for typical draws but measurably overstates the real odds as the out count climbs — at 15 outs it estimates 60% against an exact ~54% — since it's a straight-line stand-in for a curve that isn't actually linear.

Both figures are shown side by side so you can see exactly how close (or not) the quick shortcut is to the real number for your specific situation.