5 more cards
Big O calculator
Exact Big O equity across 134,459 five-card starting hand classes.
5 more cards
Flop Turn River
Pick cards to see live equity
Big O is 5-card Omaha hi-lo: five hole cards, exactly two used for the high hand and (separately) exactly two for the low, with the best 8-or-better low taking half the pot. This calculator computes the split for 2 to 6 hands, with Big O preselected, and enumerates every flop, turn and river runout exactly. Preflop it runs Monte Carlo to a ±0.3% target: this page enumerates only when 20,000 boards or fewer remain, and even a six-way pot leaves more than that until two cards are dead. Beyond total pot share it reports scoop, hi-side, lo-side and quartered rates, the numbers that matter in a game where ten two-card combos per player compress equities and pile several players onto the same nut low. Free, in-browser, with shareable links; the same tool runs O8 and Big O6, plus the high-only games and double board bomb pots.
Big O Calculator FAQ
How it works
Enter 2 to 6 five-card hands, add a board and dead cards if you have them, and watch results stream: total pot share per hand plus a split breakdown with scoop, hi-side, lo-side, both-sides and quartered rates, and how often a low is possible on the remaining runouts. Exact on any board; preflop exact when few enough runouts remain, Monte Carlo to a ±0.3% target otherwise. Copy share link reproduces the exact spot.
What is Big O poker?
Five-card Omaha hi-lo, 8-or-better: every player gets five hole cards and must use exactly two for the high hand and, separately, exactly two for the low. It is mostly a live game - the WSOP's $1,500 Big O event has drawn over 1,400 entries three years running - and pots go multiway because ten two-card combos per hand connect with almost every board. Betting is usually pot-limit. Expect looser fields than O8: more players see flops, and more of them arrive at the river with something.
How is Big O different from PLO5?
Same five cards, opposite scoring. PLO5 is high-only; Big O hands half of every pot to the best qualifying low, and that flips the rankings hard. Big O's top group is led by A-A-5-4-2 double-suited, while PLO5's best hand, A-A-T-9-9, ranks 46,387th of 134,459 Big O classes. PLO5 sits in the game selector of the same game selector above (or press L to flip scoring), so you can score the same five cards both ways on one page and see exactly what the low half costs a high-only hand. Switching scoring clears the slots, so enter the hand again after the flip.
When does a low qualify in Big O?
Two of your five hole cards plus three board cards: five distinct ranks, all 8 or lower. Aces count low, straights and flushes are ignored, and the wheel (5-4-3-2-A) is the nut low. The board must carry three distinct ranks 8 or lower, or no low exists and the high hand scoops. With five hole cards, low combinations are everywhere - lows get made, and tied, more often than in O8 - so the low-possibility line under the equity bar and the Quartered column deserve a look on every hand.
How do I read the scoop and quartered numbers?
Scoop first. A scoop takes the whole pot - both halves, or the high when no low qualifies - while a split mostly hands your own money back minus rake. A hand that scoops 30% of runouts earns more than one that wins a half 60% of the time, and the gap widens in Big O because more players share each nut low. Quartered counts runouts where you win only a tied half: two nut lows and their high win pays them 75% and you 25%. Pot share built on scoops is real; the same share built on tied lows is worth much less than it looks.
Where are the Big O starting hand rankings?
At /big-o-starting-hand-rankings: all 134,459 five-card classes simulated under real hi-lo scoring, next to the 16,432-class O8 table, with a CSV download of the Big O top 1,000. The pattern at the top: aces plus connected wheel cards, double-suited. Broadway-heavy hands that look strong in high-only PLO5 slide far down the table once half the pot plays for low. Look up your hand there, then bring it back here and test it against the exact hands you are facing.