Big O, PLO5 and PLO6

Big O is five-card Omaha Hi-Lo: you get five hole cards, use exactly two with three board cards, and the pot splits between the best high and the best qualifying low. PLO5 and PLO6 are the high-only versions with five or six hole cards, played pot-limit.

How it works

The rules are the same as Omaha with extra cards in your hand. You still make your hand with exactly two hole cards and three board cards, but you have more combinations to choose from: 6 pairs with four cards, 10 with five, and 15 with six. That means more made hands, more draws, and closer equities. Big O uses the same 8-or-better low as Omaha Hi-Lo. Some events add extras such as double-board pots or knockout bounties, so read the lobby rules.

Rules and hand rankings

Same rankings as hold'em for the high hand. Exactly two hole cards and three board cards are required.
Big O: the pot splits between the best high hand and the best low (five different ranks, none above 8, aces low, straights and flushes ignored). If no low qualifies, the high wins it all.
PLO5 and PLO6: high hand only, so there is no low and no split.
Mixes: Big O appears in Phenom's Big Bet Mix and Standard Mix, and Phenom's Big Bet Mix also includes pot-limit 5-card Omaha.

Worked example

In PLO5 you hold A♠ K♥ Q♦ J♦ 9♠ and the board is 7♠ 2♠ 5♠ K♣ 3♦. Only two of your cards are spades (A♠ and 9♠), which is exactly the number you must use, so A♠ 9♠ with the three board spades 7♠ 5♠ 2♠ gives the ace-high flush, the nut flush. The other three cards don't help this flush, but they give you extra pairs, straights and low combinations on other boards, which is why equities run so close in these games.

Strategy tips

Play connected, coordinated hands where all five or six cards work together. Rainbow, disconnected hands lose value fast.
Aces are less special than in hold'em and even less special in PLO5 and PLO6. Don't overplay a single pair of aces.
Be careful with second-best draws such as a non-nut flush draw. With more cards, someone often has the nuts.
In Big O, favour hands with an ace and a deuce plus a connected high-card structure so you can scoop.
Expect bigger swings. Equities run close and pots grow quickly with pot-limit betting.
Practice with a free equity calculator that supports five and six hole cards to see how close hands run.

Common mistakes

Playing too many hands because you have more cards
Overvaluing a pair of aces or a lone high card
Not counting that you must use exactly two hole cards
Chasing flushes that are not the nut flush

Learn more (free)

Independent free articles and rules pages, not our content. We link them because they teach the game well. Each link was checked on 2026-10-24.

Find these tournaments

Big O and PLO5 Hi-Lo tournaments → Big O at Phenom Poker → PLO5 tournaments → PLO6 tournaments → All PLO tournaments →

Verified in our data on Oct 24, 2026: Big O and PLO6 at Phenom Poker and Clubs Poker, PLO5 at ACR, Clubs Poker and Phenom Poker, and 5-card PLO8 (Big O style) at ACR. Source: each site's published schedule.

FAQ

What is Big O poker?

What is Big O?

Five-card Omaha Hi-Lo: five hole cards, exactly two used, a high/low split pot with an 8-or-better low.

What is the difference between PLO5 and Big O?

PLO5 is pot-limit and high only. Big O splits the pot with a low hand, and it is often played pot-limit.

What does Double Board mean in PLO5 and PLO6 events?

It is a common name for pots dealt with two boards, with each board awarded half the pot. Phenom's rules pages don't define it, so check the lobby for the exact rule in your event.

Is PLO6 harder than PLO5?

The rules are the same, but with six cards the equities are closer and nut draws matter even more, so it rewards disciplined hand selection.

Which finder sites run these games?

On Oct 24, 2026 we list Big O at Phenom Poker and Clubs Poker, PLO5 at ACR, Clubs Poker and Phenom Poker, and PLO6 at Clubs Poker and Phenom Poker.

Play responsibly. Tournaments are entertainment, not income. Set a budget and time limit, and never chase losses. 18+/21+ depending on site and state. Help: 1-800-GAMBLER.

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Not legal advice. Online poker and sweepstakes laws vary by state, so check your local laws before you play. Only PokerStars (US), BetMGM Poker (US) and WSOP Online are licensed in the US, and only in the states they list (NJ/PA/MI, NJ/PA/MI and NV/NJ/MI/PA). Offshore and crypto sites (Ignition, ACR, BetOnline, CoinPoker, Phenom) are not licensed in the US. GGPoker doesn't accept US players. CoinPoker accepts US players even though its terms list the US as restricted. Sweepstakes sites exclude some states.

Schedules come from each site's public pages, and each listing shows its source and the date we last checked it. Items marked unverified conflict across sources or are out of date. Always confirm in the poker lobby. SC (Sweeps Coins) and CHIP are treated as about $1 for stake tiers.