Kelly's criteria

Kelly's Criteria was developed in 1956 by John L. Kelly. Kelly´s theory is designed to maximize the growth of your bank roll (e.g. a betting fund) over the long term by determining the optimal stake on a bet. It requires that your percentage-estimations are better than the bookmakers estimations. In case of that, the following formula will tell you the optimal amount of your fund to bet:

Formula: (odds x estimation - 1)/(odds - 1)

Here is the example:
Bettingfund: $1000
Odds: 5,00
Estimation: 0,25 (25 %)
(5,00 x 0,25 - 1) / (5,00-1) = 0,0625

This means that you should bet 6,25 % of your fund = $62,5
Many punters use Kelly's formula, other find it too risky, because it requires a lot of your percentage estimations. Even if you manage to find value bets, bets with an overrated value can cost you some money, because the stake, found with the formula, is too high. You can to use a fraction system, e.g. divide the percentage with 2, which will minimize risk. Another possibility is to use Kelly's formula to determine stake proportions, i.e. to help you find out how much to bet on game 1 compared to game 2. This can be done the following way:

According to the Kelly Formula you should bet 4% of your fund on game 1 and 2% of your fund on game 2. If you are going to place for example 100$ on these two games, you should use 4/6 = 66,7 % = 67$ on game 1 and 2/6 = 33,3% = 33$ on game 2.

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