The Stack-to-Pot Ratio, or SPR for short, is defined as the ratio of the effective stack-size divided by the size of the pot. It is important to know for betting and commitment purposes.
For example, if the effective stack size (smaller of the two stacks) is $200 and the pot is $50 the SPR is 4. This means you have enough to call or bet a pot size bet on the current street and the next one.
As the SPR gets smaller, the more committed to the hand you become, and vice versa the higher the SPR, the less committed you are, meaning you need a stronger hand to commit your stack with.
In the video below, you will learn more about the critical no-limit hold’em concept of SPR.
The concept was first introduced by Ed Miller in the book Professional No-Limit Hold ’em: Volume I