Maximum Deviation (Slippage Tolerance)

Maximum deviation, also called slippage tolerance, is a setting that limits how far the execution price may move away from the requested price before an order is rejected. A trader who sets a tolerance of a few pips is telling the platform to fill the order within that band and to cancel it otherwise. A tight tolerance protects against poor fills during volatile releases but raises the chance of no execution at all; a wide one increases the certainty of getting in at the cost of price control. On MetaTrader-style terminals the option appears on the order ticket as a deviation or maximum slippage field, and it applies to market orders rather than resting pending orders.