In 2005 Dan Harrington released the second of his three part series “Harrington on Hold’em”. Since the internet poker boom around this time which is largely attributed to Chris Moneymaker’s 2003 WSOP win, poker and in particular No Limit Hold’em has changed dramatically. There are an increasing number of learning aids available, but yet Harrington’s series of books are still championed as being essential reading for the aspiring poker player.

One of the main concepts to take away from this book is Magriel’s M and how to apply it.

“The most important single number that governs your play towards the end of tournaments is M, which is simply the ratio of your stack to the current total of blinds and antes”.

The vast majority of poker players will have heard of “M” and most will be able to tell you what it is and how to calculate it. However, it seems to be increasingly common for tournament players to be discussing hands in terms of “bbs”. If there was an industry standard for structures this would be fine, but there are even subtle differences in the size of antes on Full Tilt and Poker Stars.

If we delve deeper and look at the structures on the European friendly sites the differences are staggering; Party Poker’s antes are almost negligible and appear almost as an afterthought whereas ipoker’s antes can add up to 50% more than the bb. The size of antes in live play also differs dramatically from casino to casino, some still not using antes at all but others having enormous antes, often due to the size of chips available and dealers’ eagerness to colour up the chips at the earliest point they can.

The standard size of an ante is around 10% of the big blind. Therefore an M of 5 for example usually = 12-13bbs. But as discussed, there is actually no industry standard.

To use an extreme example let’s compare ipoker and Party, and look at a specific situation where using the number of bbs you have to determine your play can be disastrous.

At the 300/600 level in the ipoker daily rebuys the ante is 100. Therefore at a 10 handed table there’s 1900 in the pot before any action takes place.

If you had an M of 5 this would be 9500 chips = 15.83 bbs

At the 800/1600 level on Party the ante is 50. Therefore at a 10 handed table there’s 2900 in the pot before any action takes place.

If you had an M of 5 this would be 14500 chips = 9.06 bbs.

The difference is clearly huge. Shoving the button with 9bbs on Party nets you the same gain as shoving the button with 16bbs on ipoker at this level.

If we were using 12bbs as being an M of 5, we’d actually be shoving an M of 6.6 on Party and an M of 3.8 on ipoker.

On Pokerxfactor.com Sheets has put up a very handy tool for calculating what hands you need to have for shoving particular M’s from particular positions based on the Nash Equilibrium¹

It’s great as a guideline, but be aware that just because something is +ev it may not be optimal. Ie shoving with an M of 10 on Party could be shoving 32bbs so a plethora of other options are available.

Also calling ranges will differ from site to site, it’s easy to see why the bb’s calling range of a 9bb shove on Party will be different from the bb’s calling range of a 16bb shove on ipoker.

Using the number of big blinds you have to determine your shoving range can be a massive leak, taking a second or two to calculate your M will benefit your game greatly.

That Harrington fella knew what he was talking about.