A coinflip in poker is any all-in situation where both players have roughly 50% equity to win the pot, typically occurring when a pocket pair faces two overcards like AK vs 22.
In poker, a coinflip doesn’t require exactly 50-50 odds. Any matchup between 45-55% equity qualifies as a coinflip, with the classic example being a pocket pair against two overcards. The term comes from the similarity to flipping a coin, where each outcome has roughly equal probability.
Despite the name, most poker coinflips aren’t perfectly balanced. A pocket pair like 66 actually has about 55% equity against AK, while AK has 45%. Understanding these slight edges and the mathematics behind coinflips is crucial for tournament play, where survival often depends on winning these pivotal confrontations.
How to Calculate Coinflip Equity
The exact equity in a coinflip depends on the specific cards involved. Here’s the basic formula:
Equity = (Number of winning outcomes) / (Total possible outcomes) × 100
Example 1: Classic Coinflip
You hold A♠K♦ and go all-in. Your opponent calls with 7♥7♣.
Pre-flop equity:
- Your A♠K♦: 45.3%
- Opponent’s 7♥7♣: 54.7%
You need to hit an ace or king to win (assuming no straights or flushes). With 6 outs twice (turn and river), the Rule of 2 and 4 estimates roughly 48% equity, close to the actual 45.3%.
Common Shortcuts
The 22 vs AK matchup serves as the baseline for all coinflip calculations:
- Small pocket pair (22-66) vs two overcards: pair is 52-55% favorite
- Medium pocket pair (77-TT) vs AK: pair is 55-57% favorite
- JJ vs AK: JJ is about 57% favorite
- QQ vs AK: QQ is about 72% favorite (no longer a coinflip)
When Does Coinflip Matter?
- Tournament bubble situations where ICM pressure affects decisions
- Short stack shoving ranges in MTTs
- Cash game situations with effective stacks under 20BB
Key Takeaway
While called coinflips, these confrontations rarely offer exactly 50-50 odds. The pocket pair typically holds a 5-7% edge over two overcards, making it slightly profitable to get all-in as the pair. In tournaments, avoiding unnecessary coinflips when you have a skill edge preserves your expected value.
