The Q-ratio (also known as Q number or just Q) is used in poker tournament strategy.
A low Q-ratio — less than 1 — indicates a below-average chip stack, implying disadvantage against opponents.
It is an addition to the M-ratio ("strong force") and usually doesn't play a large role in tournament decision-making.
However, its importance grows as the table average M-ratio drops.
On rebuy and add-on tournaments, the calculation method is somewhat more complex and possible to calculate in a reasonable amount of time only on specific online tournaments: