Identify the outcome and side
Analyzing a purchase requires asks; analyzing a sale requires bids. First check the complete question and Yes/No side, then read the bid and ask labels. Column placement can differ between interfaces, so position on the screen is insufficient.
Do not treat an entire event screen as one position. Neighboring markets can have separate books. When comparing snapshots, retain the outcome identifier: an identical heading alone does not establish that both measure the same set of offers.
Rows, levels and cumulative quantity
An illustrative ask book contains 12 shares at 0.61, 18 at 0.62 and 30 at 0.64. The first two levels total 30 shares; all three total 60. The quantity on a row is not its currency value.
Several orders can be grouped at one price, with a row showing their combined size. Aggregated quantity is enough to inspect depth. It cannot establish the number of distinct participants at that level without additional information about individual orders.
Read the average beyond the first price
For an illustrative quantity of 40, calculate 12 × 0.61 + 18 × 0.62 + 10 × 0.64 = 24.88. The average is 24.88 / 40 = 0.622. The first price of 0.61 describes only its 12 available shares.
The example assumes an unchanged book and excludes fees. It demonstrates summation rather than providing an executable quote. A requested quantity above 60 cannot be fully evaluated from these three rows because information about further offers is missing.
A snapshot and history answer different questions
A book describes open offers, a trade feed records executions and a chart displays a chosen historical price series. Increasing book quantity does not prove a completed purchase. A disappearing row likewise does not identify why open interest changed.
Record capture time, inspect nearby levels and depth, then compare with history. If one side is empty, leave its available price unknown. Substituting a midpoint does not create an opposing order that the current observation fails to show.
FAQ /
Common questions
Is order-book size a dollar amount?
It usually represents shares at a level. For an illustrative currency value, multiply quantity by price and verify the source’s units.
Will every displayed order definitely execute?
No. The book changes, and execution requires opposing interest under current conditions. A snapshot describes an observation, not a guaranteed future exchange.