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The Law of Thirds Betting System Explained (Gaming the roulette wheel?)

By Aaron Braund

27 May 2020

Aaron Braund 27 May 2020

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The Law of Thirds Betting system explained - how to use, the benefits and the results on your bankroll. Check out our short and informative guide into the Law of Thirds.

The Law of Thirds Betting Sysyem in action

An interesting system, the Law of Thirds is based on a surprisingly common statistical phenomenon in roulette.

For any 36 spins of a roulette wheel, roughly two-thirds of the numbers can be expected to appear in total. That’s 24 numbers, leaving 12 that you can expect not to appear.

That means that over 36 spins you can expect 12 of those 24 numbers to reappear, and it’s that knowledge that you can use to help increase your bankroll if you decide to use the Law of Thirds system. In this short article, we are going to show you how to use this betting strategy.

What you will learn in this article:

The theory behind the Law of Thirds
How to use the strategy (with examples)
The ways in which you can "predict" where the ball will land next

How to use the Law of Thirds roulette strategy

To play this method, all you need to do is wait for 9 separate numbers to appear. You then ignore the next couple of spins – known as the Safety Stop.

This was developed because it seemed like a good intuitive idea by the original creator of the system, and it’s stuck ever since. Players that have used this system successfully invariably use the Safety Stop though statistically, it’s of no real importance.

You then work on the basis that you can expect some of your nine numbers to appear in the next 3 spins, which – according to the Law of Thirds, one of them will. By betting on all nine numbers, you can then expect to win with odds of 35 to 1 for the cost of 27 straight-up inside bets.

Suppose, for the sake of simplicity, you bet £1 on each number. That means you’ll wager £9 on each of 3 spins, totalling £27 – and you’ll get a win of £36.

Hitting a win with Law of Thirds

It’s an appealing proposition, and does make a lot of sense when you ask yourself what the likelihood is of each of 37 numbers appearing in 37 spins of the wheel.

It makes all the sense in the world that certain numbers will appear more than once in any set of 37 spins. Guessing which numbers is a different matter - but get it right and you can enjoy a significant edge over the house.

As any grounded player or statistical expert will well you, roulette wheels do not have a memory. The likelihood of a number appearing is not made any greater by it having appeared before. Yet it is fair to say that numbers are often likely to repeat themselves, so the system is certainly not without merit. And it is certainly every bit as valid as other inside bet strategies.

If you don’t fancy your chances over 3 spins, then there’s plenty of opportunity to extend the idea. You might want to assume that 3 of your 9 numbers are going to appear in the next 9 spins, or you may wish to use another number instead of 9 to observe prior to making your bets.

Anything more than around 12 would be unwise as you’ll start to experience too much repetition before you even start betting, which doesn’t bode well.

Law of Thirds System in Action

If you’re truly cynical about the statistics behind the idea of the Law of Thirds, you may be interested to know that a test was carried out on a real roulette wheel (i.e., not a random number-generated virtual wheel) and the following results were obtained after observing thousands of spins:

Within 20 spins, 16 numbers came up, 4 of which appeared twice.
Within 37 spins 23 or 24 different numbers appear on average; 10 of these appear twice and 2 or 3 appear 3 times.
Within 110 spins 35 numbers on average appear, of which 28 appear twice. Of those 28 numbers 20 appear 3 times; of those 20, 12 appear 4 times; of those, 12, 6 appear 5 times; of those 6, 3 appear 6 times and of those, 1 appears 7 times.

Does the Law of Thirds System work?

The record for consecutive winning sessions using the Law of Thirds is reputedly 21: That’s 21 successful rounds of making straight-up bets and beating the expected table odds of 35 to 1, which is hard to ignore by anyone’s standards.

If nothing else, you won’t get sucked into a negative progression spiral with this method, making increasingly larger bets and taking bigger and bigger risks which some other methods do require you to do.

In essence it’s a pretty clever idea that’s every easy to execute – which makes it a very attractive proposition indeed for many players.

Read about other popular betting systems like:

The Martingale System

The D'Alembert System

The Labouchere System