The Chen formula, scored properly

What the Chen formula actually measures

It's always good to start with clear definitions. The Chen formula, developed by mathematician and professional player Bill Chen, converts any two-card Texas hold'em starting hand into a single points score without running a full equity simulation. It's a mental-arithmetic shortcut built to be usable at the table, not a solver, it doesn't know who you're playing against or what position you're in, it just rates the raw strength of the two cards themselves.

The formula, broken into its four rules

The score builds up in four steps, applied in order:

• Base value from the higher card. Ace scores 10, King 8, Queen 7, Jack 6, and any card 2 through 10 scores half its rank (a 9 scores 4.5, a 6 scores 3).
• Pairs double the base, with a floor of 5. A pair uses its own card's base value doubled, so pocket sevens (base 3.5) doubles to 7, while any pair below fives is bumped up to a minimum of 5 points, since even a weak pair has real value.
• Suited adds a flat 2 points. Any non-pair hand where both cards share a suit gets +2, reflecting the extra chance of making a flush.
• Unconnected cards lose points for the gap. Count the cards strictly between the two you hold: a 1-gap hand (like J-9) loses 1 point, a 2-gap (J-8) loses 2, a 3-gap (J-7) loses 4, and 4 or more gap loses 5. If the gap is 0 or 1 and the higher card is a queen or lower, add back 1 point for the extra straight potential of a low, tightly connected hand.

A worked example: J9 suited

Take jack-nine suited. The higher card is the jack, which has a base value of 6. Because the hand is suited, add 2, bringing it to 8. The gap between jack and nine is exactly one card (the ten), a 1-gap, so subtract 1, bringing it to 7. Finally, since the gap is 1 or less and the high card (jack) is queen or lower, add the connector bonus of 1, landing on a final score of 8, comfortably in the "strong" band. Try it in the calculator above to see the same result come out the other end.

How to read the score

• 10 and above, premium: raise from any position, hands a solver opens nearly 100% of the time.
• 8 to 9.9, strong: raise from most positions, strong enough to three-bet in many spots.
• 6 to 7.9, playable: fine to open late or call a single raise, weaker the earlier you act.
• 4 to 5.9, marginal: speculative, worth playing cheaply, in position, or as an occasional bluff-raise.
• Under 4, fold: below the line for almost every seat at a full table.

What the Chen formula doesn't account for

You might be right to wonder how a single number can capture a decision this situational, and honestly, it can't fully. The formula rates a hand in a vacuum: it has no idea whether you're first to act at a nine-handed table or on the button against one limper, no idea how deep the stacks are, and no idea whether the table is playing tight or loose. Two hands with the same Chen score can be worlds apart in real value depending on those factors. It also says nothing about how a hand performs against a specific opponent's likely holdings, which is a different question entirely, and exactly what the equity calculator on this site is built to answer. Think of the Chen score as a fast, honest first pass, not the final word.