The Fundamental Theorem Of Poker - Lecture One
21 May 2010
In his opening lecture, Nik Persaud introduces us to the concept of equity and why it's important to calculate.
Dr. Persaud

Lecture One: Calculating Equity

•    Why is maths important in poker?

In this lecture series, there will be plenty of mathematical ideas and calculations that will be taught. This is not pure geekyness – maths is absolutely essential to poker. If we look at the fundamental theorem, central to its understanding is the concept of pot odds. Without an understanding of pot odds, it would be practically impossible for you to win at poker. But these lectures will go a lot further than to just teach you the simple pot odds you would need.

In today’s game, where more and more people are competent poker players, it is becoming essential to understand and be able to apply various other mathematical ideas and calculations. Although it is possible to hear of someone becoming a very good winning player without learning these ideas, it is highly unlikely. It takes thousands and thousands of hands for variance in poker to play out, and for someone to know they are making correct decisions all the time without mathematical knowledge, they would have had to have run perfectly enough to learn the exact correct decision for every possible situation. That will be extremely rare.

•    Basic Equity Calculation. What is equity?

So, the first mathematical concept we’ll cover will be that of equity. Equity roughly means, "chance to win". When we defined the fundamental theorem of poker, we didn’t define exactly what it means to be "winning in a hand". Equity is the concept that defines whether you are winning or losing in a hand.

If you’ve ever watched poker on television, you will have seen that a number percentage is displayed next to the player’s hole cards. This percentage is the player’s percentage chance of winning the hand, also known as the player’s equity in the hand. Whichever hand has the most equity at the point of calculation is the favourite to win the hand, and can be said to be "winning".

•    How to find out your equity in a hand.

There are many equity calculators online, and it will pay for you to practice using them – after you play a session online, keep your hand histories, and look up the equity of you and your opponent’s cards for every decision both pre- and post-flop, every time you don’t know it offhand. This will give you a good idea of how often your hands should be winning, and to practice putting the fundamental theorem to use. Over time, it will make your decision-making easier.

Some equity calculations you might find surprising – often, people think they are getting bad beats when in reality they weren’t much of a favourite to win the hand at all. One of the most popular equity calculators, and the one I would personally recommend, can be downloaded at It's a very important piece of software and has a number of uses which can be investigated at a future date, but for now, I'd advise that you check out the site, download the software and have a play around with it. As the site says itself, "Determining the odds in a game like no-limit Texas Hold'em can require some complicated calculations," and programs like PokerStove will aid you in this process and help you to arrive at the most mathematically reliable decision.

Read Lecture Two...

Last week: Introduction...

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