How to Read an Order Book: Bids, Asks, and Depth
An order book is a live list of buy orders (bids) and sell orders (asks) for a market, sorted by price. You read it from the middle out: the best bid and best ask sit at the top, the gap between them is the spread, and the size stacked at each price is the depth that decides how far a trade moves price.
Table of Contents
The short version
An order book has two sides: bids (buyers) below the price and asks (sellers) above it. Read it from the middle out. The best bid and best ask meet at the top of the book, and the gap between them is the spread. The size resting at each price is the depth. Thick depth near price means large trades barely move it; thin depth means a small trade walks through several levels. A cluster of orders below price is support; a cluster above is resistance.
The two sides: bids and asks
Every order book has a bid side and an ask side. The bid side holds buy orders, each with a price a trader will pay and a size. The ask side, also called the offer side, holds sell orders, each with a price and size. Bids sit below the current price and ask prices sit above it, because no seller posts under the going rate and no buyer posts over it.
Orders sort by price. The highest bid and the lowest ask sit closest to the middle, where a match is most likely. As you move away from the middle, bids fall in price and asks rise, and the orders get more speculative: buyers hoping for a dip, sellers hoping for a spike.
The spread and the top of book
The best bid is the highest price anyone will pay right now. The best ask is the lowest price anyone will sell at right now. Together they are the top of the book, and the gap between them is the spread.
The spread tells you the cost of trading at once. A tight spread, a cent or two on a liquid market, means buyers and sellers almost agree and a round trip costs little. A wide spread means the two sides are far apart, and you pay that gap the moment you cross it. Liquid, heavily traded markets run tight spreads; thin or new markets run wide ones.
Depth: the size that decides slippage
Price is only half of each order; size is the other half. Depth is the total size resting at each level, and it decides how far your trade moves the price. This is the part that separates a trader who reads the book from one who only reads the last price.
Say the best ask holds 2 SOL and the next ask up holds 50. A buyer who wants 40 SOL eats the 2 at the best price, then climbs into the next level for the rest, paying more the whole way. That climb is slippage: the difference between the price you saw and the average price you got. Thick depth near price keeps slippage small. Thin depth means even a modest order walks the book and moves the market against itself.
A quick way to size up any book
Ask two questions. How wide is the spread? And how much size sits within a few levels of the price? A tight spread with heavy nearby depth is a market you can move size in cheaply. A wide spread with thin depth is a market where every trade pays up.
This is exactly the read that finds real support and resistance, which is the next section.
Market orders vs limit orders
Two order types build and consume the book. A limit order sets an exact price and rests in the book until someone trades against it. A market order takes whatever the book offers and fills now, sweeping from the best price outward until it is done. Matching follows price-time priority: better prices fill first, and at the same price the order that arrived earlier fills first.
| Market order | Limit order | |
|---|---|---|
| What it does | Fills now against resting orders | Rests in the book at your price |
| Price control | Takes whatever the book offers | You set the exact price |
| Fill | Immediate, but may slip | Only if price reaches it, may never fill |
| Liquidity role | Taker, removes liquidity | Maker, adds liquidity |
| Typical fee | Higher, and pays the spread | Lower, and earns the spread |
Makers post the resting orders that fill the book; takers cross the spread to trade against them. Every level you see is a maker's limit order waiting for a taker.
Reading walls: support and resistance
Once you read depth, support and resistance stop being lines on a chart and become size in the book. A large cluster of bids below price is a buy wall: real orders that have to be eaten before price can fall through that level. A large cluster of asks above price is a sell wall: orders that cap a move until buyers clear them.
Walls are information, not promises. A big resting bid can be pulled the instant price approaches, and a wall can be posted to fake a floor that vanishes on the first push. Read walls as where the current orders sit, then watch whether they hold when price arrives. The skill is the same whether the orders live in a literal book or in pool liquidity.
Order books on Solana, and CLOBr's depth view
Solana runs real on-chain order books. Phoenix is a fully on-chain central limit order book, and OpenBook is a community-run book that forked from Serum. Jupiter limit orders rest on-chain too, executed by off-chain keepers when price reaches them. For the background on order books as an exchange model, see What is a CLOB?
Most Solana volume, though, trades on AMMs and concentrated liquidity, not order books, so the depth is scattered across pools instead of listed in one place. That is the gap CLOBr fills. It aggregates every pool's bins, constant-product depth, and resting DCA and limit orders into one depth chart, then buckets it into price levels. The result reads like an order book: buy walls below, sell walls above, and the thin gaps where price can run.
See the depth for any Solana token
CLOBr gives Solana traders the order-book view that AMMs hide: aggregated liquidity from Meteora, Orca Whirlpools, and Raydium, bucketed into support and resistance you can read at a glance.
See aggregated liquidity for any tokenTo connect this depth read to concentrated liquidity, see DLMM vs AMM vs Order Books and What is a DLMM?
Frequently Asked Questions
How do you read an order book?
Start in the middle. The best bid (highest price a buyer will pay) and the best ask (lowest price a seller will take) meet at the top of the book, and the gap between them is the spread. Below the best bid, buy orders stack down in price; above the best ask, sell orders stack up. The size resting at each price is depth. Large size near price means the market can absorb big trades without moving much.
What is the difference between the bid and the ask?
The bid is the price and size a buyer is offering to pay. The ask, also called the offer, is the price and size a seller wants. The best bid is the highest buy order and the best ask is the lowest sell order. Buyers who want to trade now pay the ask; sellers who want to trade now hit the bid.
What is market depth?
Depth is the total order size resting at each price level. A deep book holds large size near the current price, so a big order fills with little slippage. A thin book moves through several levels on a modest order, so the same trade costs more. Reading depth is how traders judge how far price can move before it runs out of orders.
What is the difference between a maker and a taker?
A maker posts a limit order that rests in the book and adds liquidity. A taker sends an order that fills against those resting orders and removes liquidity. Exchanges usually charge takers a higher fee, because makers supply the liquidity everyone else trades against.
Do AMMs have an order book?
Not a literal one. An automated market maker prices trades from a pool and a formula instead of a list of orders. But concentrated liquidity behaves like resting orders: a dense band of liquidity below price acts as support, a dense band above acts as resistance. CLOBr turns Solana pool liquidity into that order-book style depth view.