Crypto Order Book & Depth of Market (DOM) Explained
TL;DR. The crypto order book is the live queue of resting buy and sell orders on an exchange, and the depth of market (DOM) is the ladder view of its best levels. It shows where liquidity is waiting and at what price, which is why every level, sweep and breakout in this section is explained through it. It does not show intent: a resting order can be cancelled in a millisecond, and the book beyond an obvious level is empty of limit orders and full of invisible stops. Reading the book well means treating resting size as context and executed trades as fact.
Prerequisites for this lesson: Order types (limit, market, stop), How crypto prices move (aggressors and passive orders). Lesson 1 of the market mechanics section.
What the order book is
Every exchange that runs a limit-order market keeps an order book: two lists of resting orders, updated in real time.
- Bids: buyers willing to buy at a stated price or lower, listed below the current price in descending order.
- Asks (offers): sellers willing to sell at a stated price or higher, listed above the current price in ascending order.
The gap between the best bid and the best ask is the spread. On BTC/USDT perpetuals at a major exchange it is usually one tick, $0.10 on a $100,000 contract, a hundredth of a basis point; on smaller coins it can be several tenths of a percent.
A market order matches at once against the best resting order on the other side. You pay the spread as an implicit cost and the taker fee as an explicit one, which is why scalpers prefer limit orders that rest in the book, pay the maker fee, and fill at the price they name or not at all. The execution lesson works through what the difference costs over a month.
Depth of market: the ladder
The DOM shows the ten to twenty best levels on each side with the size resting at each. On a quiet afternoon with BTC at $100,010 it might look like this:
ASK side (sellers)
──────────────────────────────
Price │ Size
──────────────────────────────
100,250 │ 12.4 BTC
100,200 │ 8.1 BTC
100,150 │ 31.7 BTC ← large resting ask
100,100 │ 5.2 BTC
100,050 │ 3.8 BTC
──────────────────────────────
LAST: 100,010
──────────────────────────────
100,000 │ 9.4 BTC
99,950 │ 6.1 BTC
99,900 │ 28.3 BTC ← large resting bid
99,850 │ 4.7 BTC
99,800 │ 2.9 BTC
──────────────────────────────
BID side (buyers)
The 31.7 BTC at $100,150 is a possible resistance level: buyers would need to absorb it before price can trade higher. The 28.3 BTC at $99,900 is possible support. The word "possible" is doing real work in both sentences, for reasons the next sections explain.
The depth chart shows the same information as a curve: cumulative size stacking outward from the current price on both sides. A wall appears as a step.
What the DOM tells you
Immediate supply and demand. Before a long, a scalper looks at what sits directly above: a thin ask side means less resistance to an upward move; a wall means price will need volume to get through, or will stall.
Imbalance. Compare total bid size against total ask size within a narrow band of the current price. A book that is heavily bid near the price is a mild short-term bullish sign, mild because the orders that make it up can be pulled.
Absorption. A large order sits at a level and price touches it repeatedly without getting through. The order is absorbing the traffic against it. Absorption of wave after wave of selling at one bid is the clearest sign the book gives that a level is being defended, and the order flow lesson shows how to confirm it from the tape.
Thin zones. Beyond an obvious level the book is thin: a few BTC per level instead of tens. That is not a signal to trade; it is a warning about slippage and about what happens when the level gives way, which the ranges lesson describes.
What the DOM does not tell you
The book shows resting orders, not intent, and three things follow.
Spoofing. A large order appears, traders read it as support, and it is cancelled as price approaches. It was never meant to fill. Spoofing is illegal on regulated futures exchanges and against the terms of every crypto venue, and it happens on crypto venues daily. A single large resting order is never a certainty.
Hidden size. Iceberg orders show a slice and refill it from a hidden remainder. The book shows 5 BTC while 300 BTC sits behind it, revealing itself as each slice fills. The visible book is always incomplete, in both directions: hidden bids can hold a level the DOM says is thin, and a visible wall can be the only order at its price.
Speed and latency. A liquid perpetual's book updates many times a second. What you saw 200 milliseconds ago may already be gone, and a retail connection sees the book with a delay of that order. For a trader working the 1-minute chart this matters little; for anyone trying to trade the ladder tick by tick it is the whole game, and the API vs interface lesson covers what a retail setup can realistically do.
Intentions and facts
One principle organises everything else in this lesson:
The order book shows intentions. Trades show facts.
A resting bid at $99,900 is a statement: "I am willing to buy here." Until it fills it is provisional. A completed trade, a market order consuming that bid, is a fact: someone paid that price and chose to take rather than wait. Weight the two accordingly. Resting size is context; executed aggressive trades are the signal. Rubén Villahermosa Chaves puts it in one line in Wyckoff 2.0: the tape is the past and cannot be manipulated; the book is intention and can be withdrawn.
CVD: aggression over time
Cumulative volume delta extends the fact side of that principle across time. It is the running total of aggressive buying minus aggressive selling: trades that lifted the ask minus trades that hit the bid.
CVD = Σ(taker buy volume) − Σ(taker sell volume)
| Price | CVD | Reading |
|---|---|---|
| Rising | Rising | Buyers are driving the move: a trend with participation |
| Rising | Falling | Price up on net aggressive selling: someone is absorbing the sellers, or the rise is short covering; a divergence to respect |
| Falling | Rising | Price down while aggressive buyers step in: a possible floor forming |
| Falling | Falling | Sellers are driving the move: a downtrend with participation |
The most useful reading is the divergence: price makes a new high and CVD does not. The move was not carried by aggressive buying, which points to short covering or a thin book rather than demand, and it often precedes a reversal. CVD on its own is not an entry; with the book and the structure it separates a move with conviction from one without.
The book in motion
A snapshot of the DOM is a small part of the information. The rest is how it changes:
- Market orders hitting the bid: aggressive selling; someone is taking the available price to get out or get short.
- Market orders lifting the ask: aggressive buying.
- Bids stacking: new resting buy orders queuing quickly below price; building interest.
- Bids pulling: resting bids disappearing as price approaches them; the buyers who placed them are stepping back, a short-term bearish sign, and the mechanism behind a spoof.
- Refills at one price: a level that keeps trading without depleting; an iceberg.
The order flow lesson in the strategies track builds the trading use of these signals, with numbers.
Practical use for scalpers
Entry check. Before a long, a thin ask side immediately above and stable bids below is a better environment than a wall overhead. It does not make the trade; it removes one reason not to take it.
Target. A large resting ask at a round number ($105,000) is a natural first target; price often stalls there even when it eventually breaks through.
Stop reference. Long from $100,000 with 28 BTC resting at $99,900: a stop just below that bid is more logical than a stop a fixed number of dollars away, because if the bid is consumed the premise of the trade has changed.
Size. A thin, quiet book moves faster in both directions. Positions are smaller when the book is thin, which is the same rule as sizing by ATR from the other direction.
Where to see it
Every major exchange shows the book in its interface. For richer views: Binance Futures publishes a btcusdt@depth20@100ms WebSocket stream; Bybit and OKX have equivalents; TradingView shows a simplified DOM for supported instruments; Bookmap, Sierra Chart and Exocharts record book history and show it as a heatmap, which makes icebergs and pulled bids much easier to see than a ladder does. The tools section discusses the choices.
Where to go from here
The book is the surface on which every other mechanism in this section acts. The next lesson uses it to explain why price spends most of its time in ranges and what the edges of a range are made of.
- Trading ranges: the liquidity map of a range and why the edges get poked.
Related guides:
- Order flow and DOM for scalpers: absorption, aggression, icebergs and spoofs as trade confirmation.
- Order types: limit, market and stop orders and what each does to the book.
- Trade execution: maker and taker fees, slippage, the cost of crossing the spread.
- Liquidations: how the book behaves when forced orders arrive in waves.
- Position sizing and risk management: sizing for a thin book.
- Crypto market mechanics: the section hub.
- Glossary: order book, DOM, spread, CVD, iceberg order.
This article is educational content, not investment advice. Trading derivatives carries substantial risk, including total loss of capital. See disclaimer.