Wong Halves System

Omega II System for Card Counting in Blackjack

The Wong Halves System is hard to use, but it's a strong system. The system was first published in Stanford Wong's book Professional Blackjack. It's a level 3 strategy, which means you have 3 different card values to keep up with. It's also one of the only card counting systems we've seen that involved using fractions.

We cover a "cheat" for how to deal with that aspect of the system if you're bad with fractions, but it only makes the system easier if you're one of those folks who have trouble with fractions. The system is complicated enough that even with the cheat, you might have a lot of trouble with it. We're not convinced that it's worth the trouble, but we weigh the pros and cons below.

How to Count Cards Using the Wong Halves System

With any card counting system, your goal is to get an idea of what the ratio between high cards and low cards in the deck is. The Wong Halves System is no different in this respect.

But most card counting systems only require you to add and subtract a value of 1 to and from your count. Some more complicated systems might require you to add and subtract a value of 2 for some cards in addition to this.

But in the Wong Halves System, you have to track 3 different values. Here's what to add or subtract from your count when you're using this system:

  • Aces and 10s are worth -1
  • 2s and 7s are worth 0.5
  • 3s, 4s, and 6s are worth 1
  • 5s are worth 1.5
  • 9s are worth -0.5
  • 8s are worth 0

Remember earlier when we mentioned a cheat that will make it easier to keep up with the counts? All you have to do is double the values above, and that eliminates the fractions. You just have to remember if you do that, the count is twice as high as it should be.

Here are the revised values when doubled:

  • Aces and 10s are worth -2
  • 2s and 7s are worth 1
  • 3s, 4s, and 6s are worth 2
  • 5s are worth 3
  • 9s are worth -1
  • 8s are worth 0

Even with that adjustment, it still looks like a hard, complicated system to use, doesn't it?

That's because it is.

You'll use this system to know when to raise your bets and adjust your playing strategies. We'll cover more about that later on the page, but know this:

Most of the edge you gain from any counting system comes from your ability to raise your bet when the deck favors you.

The basic strategy adjustments that you'll make only come up 10% of the time. And those adjustments add a relatively low amount to your mathematical edge against the casino—less than 0.5%, even in the case of a relatively powerful system like this one.

This system is designed for someone who wants to milk every percentage point from the casino.


Even when using the most accurate card counting system in existence, you're still gambling. You're not guaranteed a winning session, ever. You need to have a big enough bankroll in order to weather the storms of fate and fortune.

Running Count Versus True Count

Like most counting systems, the Wong Halves system also requires you to convert the running count into a true count. We cover that subject in great detail on our main page about counting cards, but briefly, here's what this means and why:

Card counting systems track the ratio of high cards to low cards in a single deck of cards. Each card has an effect on the odds as it's dealt.

That effect is minimized by how many decks are in play.

It's easy to see why. There's a big difference between dealing out 2 aces from a deck with 4 aces in it and dealing out 2 aces from a deck with 32 aces in it. In the first case, you've reduced the chance of getting a blackjack by 50%, but in the 2nd, it's more like a 7% chance.

To convert the running count into a true count, you simply divide the count by the number of decks left in the shoe.

Sizing Your Bets and Managing Your Bankroll

You should always maintain a large enough bankroll that you can weather a streak of bad luck. This is called variance by the mathematicians, but it comes up all the time. We recommend that you maintain a bankroll of at least 200 times your minimum bet size. 1000 times your minimum bet size is even better.

This means that if you're planning to play games with a $5 minimum bet, you should have a bankroll of between $1000 and $5000.

This gives you enough room to raise and lower your bets based on the count, but it also minimizes what gamblers and mathematicians call "risk of ruin".

That's just a fancy phrase that describes the likelihood that a streak of bad luck will wipe out your bankroll.

On the low end of that recommendation, you face a 40% risk of ruin, but at the top end, you only face a 1% risk of ruin. Your tolerance for risk should determine your bankroll requirements, but those are the minimum guidelines.

Please Note

You should also keep in mind that it doesn't matter how much of a bankroll you have, if your game isn't close to perfect, you'll eventually lose all your money to the casino. The only way to get an edge over the casino is to play with near-perfect basic strategy and use near-perfect bet sizing while playing.

This is the biggest drawback to the Wong Halves System. Playing it near-perfectly is going to be next to impossible for most casual card counters. And we're not sure that the increased accuracy is worth the extra effort. Maybe you're just looking for an intellectual challenge?

At any rate, be sure to cut the true count in half if you've doubled the count to eliminate the fractions as we suggested above.

Then size your bets according to the same strategy we recommend with the other systems. Decide on a betting range before sitting down, and then know which counts trigger the next level of betting.

Here's an example:

  • If the count is negative, 0, or 1, you're going to bet $5.
  • If the count is 2, you're going to bet $10.
  • If the count is 3, you're going to bet $15.
  • You're willing to go all the way up to $100 per bet if the count gets as high as 20.

If you get a copy of Professional Blackjack, you can study this system in depth and get more accurate advice for both sizing your bets and for adjusting your strategy decisions.

Much of the information used in this write-up was found at Norm Wattenberger's excellent site, QFIT, where he provides detailed analysis of multiple card counting systems.


The Wong Halves System for counting cards in blackjack is a hard system to learn and a harder one to implement. We only recommend it to the most dedicated card counters who are looking for a challenge.

What makes it hard to implement are the 3 levels required to keep up with. The simpler strategies only require you to add and subtract 1, but this one requires you to keep up with 3 different values and even keep up with fractions.

It's more trouble than it's worth, in our view, but it's interesting to think about.

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