What is VPIP in Poker?

Short for Voluntarily Put Money In Pot, VPIP is a statistic used to measure how tight or loose a player is based on the percentage of hands that a player voluntarily plays preflop.

For example, suppose you have played 10 hands at a particular poker table. If you called or raised before the flop in 4 of those hands while folding the other 6, your VPIP would be 40%.