Big O

It’s like Omaha Hi-Lo, except you get a fifth hole card

You know Omaha Hi-Lo: four hole cards, five board cards, use exactly two from your hand and exactly three from the board, half the pot to the best high and half to the best 8-or-better low. Big O is that, with one extra card in your hand. Nothing else changes.

That one card is a bigger deal than it sounds. Four hole cards give you 6 different two-card pairs to play. Five give you 10. More pairs means more people holding A-2, more people holding a flush draw, more people holding the nut straight. In Big O, “pretty good” loses all the time.

30-second cheat sheet

• Five hole cards each. Blinds, flop, turn, river, four betting rounds, same as Omaha.
• High and low halves, exactly like Omaha Hi-Lo. Exactly two hole cards and exactly three board cards for each hand. Having five suited cards in your hand does not make a flush.
• A low needs five different ranks, all 8 or lower, aces low. The wheel (A-2-3-4-5) is the best low.
• No qualifying low? The best high wins the whole pot.
• Normally played pot-limit. Sometimes limit. Eight players maximum at the WSOP.
• If someone just says “Big O,” ask whether they mean 8-or-better. Some rooms use that name for five-card Omaha high only.

Full rules

The deal

There’s a dealer button and blinds (the WSOP also allows antes or a mix of both). Everyone gets five cards face down. There’s a round of betting, then the dealer burns a card and puts out a three-card flop, burns again for the turn, and burns again for the river. There’s a betting round after each, so four in total.

The WSOP caps the game at 8 players. The math is simple: eight players is 40 hole cards, plus three burns, plus five board cards, which uses 48 of the 52. Nine would run out of deck. (That arithmetic is ours, not a WSOP quote.)

Building your hands

You build two hands, one for each half of the pot. Each one uses exactly two cards from your hand and exactly three from the board. They don’t have to use the same two hole cards. You might use your A-2 for the low and your K-K for the high, and that’s perfectly fine.

• High: ordinary poker rankings. A flush needs three suited board cards plus two suited hole cards. A straight needs exactly three board cards in the sequence plus two of yours.
• Low: five cards of five different ranks, none higher than 8. Aces are low. Straights and flushes don’t hurt a low, so A-2-3-4-5 is both a straight and the best possible low. You compare lows from the highest card down: 7-5-4-3-2 beats 7-6-3-2-A.

Qualifying

A low that isn’t 8-or-better doesn’t exist. If the board doesn’t contain at least three different cards 8 or lower, nobody can make a low and the high winner takes the whole pot.

Ties, quartering, and the odd chip

Tied hands split their half. If one player has the best high and two players tie for low, the high takes half and each low takes a quarter. Getting quartered hurts, and in Big O it happens a lot, because five cards make A-2 very common.

The odd chip usually goes to the high half.

Rooms disagree

• The odd chip. The WSOP’s general rule gives it to the high hand, but its mixed-game procedure for button games says “worst position” (first seat left of the button). Commerce Casino gives it to the high hand, and within a tied half to the tied player closest to the left of the button. Ask the floor. This page doesn’t try to decide.
• Player cap. WSOP live-action rules say 8. WSOP tournaments play it 7-handed so a final table can seat 8. Commerce also allows 8 active players, even at a nine-seat table.
• Structure. Pot-limit is the norm in explainers and WSOP events. Commerce’s room rules are written around posted limits with a three-raise cap. Mixed-game rotations alternate limit and pot-limit levels.
• The name. At the Bicycle Hotel & Casino, a game called plain “Big O” is five-card Omaha high only, and Wikipedia uses the name the same way. The WSOP, Golden Nugget, PokerNews and Card Player use it for the hi-lo game. This page follows the WSOP.

Worked examples

Five suited cards, no flush

Five spades in hand, still no flush

Board

Alice

• High:Pair of Kings
• Low (8-or-better):6-4-3-2-A low✓ wins

Bob

• High:Three Nines✓ wins
• Low (8-or-better):7-6-4-3-2 low

Alice takes half · Bob takes half

Alice holds five spades, but the board only has two (the 2 and the 9). A flush takes exactly three from the board and exactly two from your hand, so she has no flush at all. Her best high is a pair of kings. Bob’s two nines plus the nine on the board make trips, so he wins high. For low, Alice’s A-3 with the board’s 2-6-4 is 6-4-3-2-A, a lovely low that beats Bob’s 7-6-4-3-2.

The wheel scoops

The wheel makes the nut low and a straight

Board

Alice

• High:Five-high straight✓ wins
• Low (8-or-better):5-4-3-2-A low✓ wins

Bob

• High:Three Nines
• Low (8-or-better):7-6-4-3-2 low

Alice scoops the whole pot.

Alice’s A-5 plus the 2-3-4 on the board gives her A-2-3-4-5. It’s the best possible low and it’s also a straight, so it wins high too. Bob has three nines and a 7-6-4-3-2 low. Both beaten. Alice scoops.

Three people holding A-2

Three players hold A-2 and share the low

Board

Alice

• High:Two pair, Kings and Nines
• Low (8-or-better):8-4-3-2-A low✓ wins

Bob

• High:Two pair, Kings and Queens✓ wins
• Low (8-or-better):8-4-3-2-A low✓ wins

Carol

• High:Two pair, Kings and Jacks
• Low (8-or-better):8-4-3-2-A low✓ wins

Alice takes 16.7% · Bob takes 66.7% · Carol takes 16.7%

Everybody holds A-2, so the 8-4-3-2-A low is a three-way tie. Each takes a sixth of the pot. Bob also makes two pair, kings and queens, which beats Alice’s kings and nines and Carol’s kings and jacks, so he takes the high half on top. That’s two-thirds of the pot for Bob, a sixth for each of the others.

How you’ll embarrass yourself

• Counting a five-card flush. Five hearts in your hand isn’t a flush. Exactly two from your hand.
• Playing the extra card as if it were extra. You still use two. Your fifth card just gives you more pairs to choose from.
• Overvaluing two pair and sets. With ten combinations per hand, someone almost always has a straight or flush or better. PokerNews says two pair and trips hardly ever win at showdown.
• Falling in love with second-best lows. A-3 and A-4 get quartered or beaten by the many A-2s out there.
• Playing all-high hands. K-Q-J-10-9 has a lot of high cards and zero low prospects. You can only win half the pot, and you’d better have the nuts for that half.
• Calling it “Big O” and assuming everyone agrees. At some rooms that means high only.

Lore and reputation

Wikipedia says five-card Omaha started showing up in Southern California card rooms in 2008, but that sentence carries a “citation needed” tag, so treat it as a claim. PokerNews says the name is either shorthand for “5 Card Pot-Limit Omaha Hi-Lo 8 or Better” or simply “bigger,” because of the extra card.

At the WSOP, Big O first appeared in the Dealer’s Choice event in 2015. A 2016 event mixed PLO8, O8 and Big O. According to Wikipedia’s WSOP pages, 2023 was the first year a Big O event was held, and standalone $1,500 and $10,000 Big O events have run in 2024 through 2026. Card Player notes the high variance and multiway pots.