Read both sides of the book
An order book records resting offers to trade at particular prices and quantities. The best bid is the highest available buying price; the best ask is the lowest available selling price. The difference is the bid–ask spread.
With a 48¢ bid and 52¢ ask, an immediate purchase followed by an immediate sale at unchanged quotes loses 4¢ per contract before fees. The midpoint of 50¢ is a reference, not a promised execution.
Quantity changes the calculation
Suppose an illustrative book offers 20 contracts at 52¢ and another 30 at 55¢. Buying 50 against those offers costs $26.90 before fees, for an average price of 53.8¢. The best ask described only the first 20 contracts.
Kalshi’s quick-order documentation illustrates this same principle: a larger order can consume several price levels. Inspect the quantity available, not only the most attractive visible price.
What a limit order controls
A buy limit order sets the highest execution price you will accept; a sell limit sets the lowest. A limit may fill immediately, partially, later, or never, depending on compatible orders and venue rules.
If a buy limit is 53¢ in the example above, only the 20 contracts at 52¢ are within the limit. The handling of the remaining quantity depends on the order’s duration and execution instructions.
Execution is a tradeoff
An order seeking immediate execution accepts the available book within the product’s execution controls. A resting order offers price control but introduces uncertainty about whether it will trade. A limit order that immediately crosses the book can still be a liquidity-taking order.
Fees depend on the actual fee schedule and execution. The word “limit” does not automatically mean “free.”
Liquidity can disappear
Depth is the quantity available at different price levels. Volume records trading that has already happened. A market can report substantial past volume while offering very little depth now.
Resting orders may be canceled, new information can move quotes, and trading can pause. A screenshot of a deep book is evidence about that moment, not a guarantee of a later exit.
Sources & further reading
Platform terms and rules can change. Check the linked primary sources and the specific contract before relying on a detail. How we work →