Online Poker Tools and Reviews

Risk of Ruin Calculator

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This free online tool will calculate a player's risk of ruin given their win rate, standard deviation of the win rate and bankroll size.

Enter figures between 0 and 1000000 leaving off the dollar sign ($).

The formula used in this calculator is:

Risk of Ruin = e^{-2 x WR x BR ÷ (SD x SD)}

• e = Constant (2.718281828)
• WR = Win Rate
• SD = Standard Deviation
• BR = Bankroll

This formula and calculator can be used for any gambling game (eg video poker, blackjack) in addition to poker where the player has the advantage and needs to determine risk of ruin.

Note that this calculator makes a number of assumptions which may mean the results may not be accurate. Some of these assumptions include but are not limited to:

• Formula assumes an accurate estimate of a player's win rate and standard deviation. The estimate of the standard deviation tends to converge quickly whilst the win rate may take many thousands of hands to estimate accurately.
• Formula assumes constant win rate and standard deviation. This means the player will play the same whilst winning or losing heavily and never goes on tilt. It also assumes that table conditions are constant.

Despite these limitations the given result is a reasonable ballpark estimate of a player's risk of ruin, certainly better than the standard anecdotal advice of 300 big bets providing acceptable protection against ruin.