What do numbers like 19/16 mean in poker forums?

In poker forums, you’ll often see sentences like this:

Villain was 19/16”.

Usually you’ll see two numbers in an xx/yy format. Often there’s a third number, in xx/yy/zz format. First I’ll discuss xx/yy; keep reading for xx/yy/zz.

xx/yy are VPIP/PFR

These two numbers are VPIP and PFR. Both are percentages. Together they describe how how tight or loose a player is, as well as how passive or aggressive.

Still unclear?

VPIP (Voluntarily put money in pot)

VPIP is “Voluntarily put money in pot” and is always referring to pre-flop play. A player with VPIP of 19 voluntarily puts money in the pot pre-flop 19% of the time. “Voluntarily” here means that if the only money a player puts in the pot is an obligatory blind or ante, this doesn’t get included. If the big blind calls a raise, this will be included.

If a player has a low VPIP, he is tight. If a player has a high VPIP he is loose.

PFR (Preflop raise)

PFR is “Pre-flop raise”. A player with a PFR of 16 makes a pre-flop raise in 16% of the hands he plays.

The relationship between VPIP and PFR

A pre-flop raise is always a case of a player voluntarily putting money in the pot. The maximum value for PFR is equal to VPIP. So a player’s PFR ranges from 0 to whatever the VPIP value is.

If PFR is close to VPIP, then the player almost always raises when he decides to put money in the pot pre-flop. That is, he plays aggressively. If PFR is close to 0, then the player is passive. A “calling-station” in derogatory poker parlance.

If a player has a PFR close to 0, he is passive. If a player has a PFR close to VPIP, he is aggressive.

Example: 19/16

Remember that player described as “19/16”? His VPIP is 19, making him a tight player. His PFR is 16, very close to VPIP, making him an aggressive player.

You can conclude that this player only puts money in the pot when he has very good hole cards. And when he does put money in, he usually raises. This player is typically labelled “TAG”, a shorthand way of saying “tight aggressive”.

So what’s xx/yy/zz?

Sometimes you’ll see a third component, such as 19/16/50. The third number is AF or “Aggression Frequency”.

(Note: some people use “Aggression” for the third number, which is calculated quite differently and is not a percentage. It has some problems, and so “Aggression Frequency” has become a more popular statistic.)

AF (Aggression Frequency)

AF measures how often a player bets or raises in post-flop play. Like VPIP and PFR, it is a percentage. Precisely, it measures how often a player bets or raises at least once in a hand’s post-flop play, out of all the hands in which the player sees the flop.

A player with an AF of 50 bets or raises on either the flop, turn, or river, at least once in 50% of all the hands in which he reaches the flop.

The relationship between VPIP and AF

A player who seldom sees the flop will tend to have a higher AF. So you should consider the AF value in comparison to the VPIP value.

How useful are these numbers?

VPIP, PFR, and AF are extremely useful to describe a player but only if you’ve played many hands against that player. VPIP and PFR start to become useful after 25 hands. AF, on the other hand, requires at least 25 hands in which the player reached the flop.

  • If the player sees about 20% of the flops, then you’ll need to have played 125 hands against the player to be able to trust AF.
  • If player sees about 50% of the flops, then you'll get a reasonably reliable AF after 50 hands.

Even then, remember that these numbers change depending on the type of poker, the number of players sitting at the table, and the player’s current pace of learning. They are dynamic numbers, changing over time. Use them to describe your opponents, but use them with your brain actively analysing the situation.

How can I find these numbers for an opponent?

You could manually record every player’s actions using pen and paper to calculate these statistics. Or you could use “poker HUD” software that automates this. Like the one you can see advertised all over the website you are currently on, with “Download” buttons.

Poker HUD software calculates these numbers and places the numbers directly on the poker table next to each of your opponents.