This glossary defines the roulette strategy, probability, and tool terms used across the site. Each entry is short and plain, with links to the pages that explore the idea in depth. Start with the Martingale roulette calculator to see many of these terms in action.
Core Betting and Staking Terms
Martingale. A negative progression that doubles the bet after each loss and resets after a win, so one win recovers the sequence plus a base unit.
Base bet. The starting stake of a sequence and the amount returned to after a win. Also called the initial bet or unit.
Initial bet. The first stake placed in a progression; it anchors the size of every later bet.
Unit size. One base bet expressed as a counting unit, used to describe results independently of currency.
Progression. A rule for changing the stake after wins or losses. Progressions are the basis of most roulette systems.
Negative progression. A system that increases the stake after a loss, such as Martingale, Fibonacci, D'Alembert or Labouchere.
Positive progression. A system that increases the stake after a win, such as Reverse Martingale or Paroli.
Target profit. A set amount of winnings at which a player plans to stop for the session.
Stop loss. A predetermined maximum loss at which a player plans to stop, capping the damage from a bad streak.
Probability and Risk Terms
Risk of ruin. The probability that a sequence fails before reaching its target, usually because a losing streak exceeds bankroll or table limits. See the risk of ruin page.
Expected value. The average result per dollar wagered over the long run. In roulette it equals the negative house edge, as shown on the expected value page.
House edge. The built-in mathematical advantage of the casino, 2.70% on European and 5.26% on American roulette, caused by the zero pockets.
Drawdown. A drop in bankroll from a previous peak during a session, often caused by a losing streak.
Monte Carlo simulation. Running many random sessions to estimate the range of outcomes and failure rates of a system, described on the Monte Carlo simulation page.
Roulette Bet and Table Terms
Even-money bet. A bet paying 1:1 that covers 18 numbers, such as red/black, odd/even or high/low. See the even-money bets page.
Outside bet. A bet covering a large group of numbers, including even-money bets, dozens and columns.
Inside bet. A bet on individual numbers or small groups, paying more but winning less often.
Table limit. The minimum and maximum stake a table accepts. The maximum caps how many times a progression can double.
Bankroll. The total money a player has available for betting, which determines how many losing steps a progression can absorb.
How These Terms Fit Together
These definitions connect directly. Bankroll and table limits set how deep a progression can run, drawdown describes what a losing streak feels like along the way, and expected value and the house edge determine the long-run result no matter which progression you choose. For the equations behind them, see the mathematical model page.