What Is an Order Book in Crypto? How to Read It
An order book lists every buy (bid) and sell (ask) order waiting on an exchange. Learn to read bids, asks, spread and depth with a simple SOL/INR example.
An order book in crypto is the live list of all open buy orders (bids) and sell orders (asks) for a trading pair on an exchange, sorted by price. The highest bid and the lowest ask sit in the middle; the gap between them is the spread. A trade happens when a new order meets an existing one. Reading the order book tells you how much you can buy or sell before the price moves against you.
Key takeaways
- Bids are buyers, usually shown in green; asks are sellers, usually shown in red.
- Best bid and best ask set the current market; the spread is the gap between them.
- Depth is how many coins wait at each price level. More depth means less slippage.
- Limit orders add to the book (makers); market orders take from it (takers).
- Large visible orders ("walls") can be cancelled at any moment, so do not treat them as guarantees.
The parts of an order book
Every exchange lays it out a little differently, but you will always see three columns: price, amount (quantity of the coin) and a running total. Here is a simplified SOL/INR book with illustrative numbers near SOL's price of about ₹11,886 on 27 September 2026 (live: ₹11,341).
| Side | Price (₹) | Amount (SOL) | Cumulative (SOL) |
|---|---|---|---|
| Ask | 11,920 | 5 | 10 |
| Ask | 11,900 | 2 | 5 |
| Ask (best) | 11,890 | 3 | 3 |
| Bid (best) | 11,880 | 4 | 4 |
| Bid | 11,870 | 6 | 10 |
| Bid | 11,850 | 10 | 20 |
- Best ask: ₹11,890. The cheapest price anyone will sell at right now.
- Best bid: ₹11,880. The highest price anyone will pay right now.
- Spread: ₹11,890 − ₹11,880 = ₹10, about 0.08% of the mid price of ₹11,885.
- Depth: 10 SOL are offered within ₹30 of the best ask; 20 SOL are bid within ₹30 of the best bid.
How orders interact with the book
If you place a limit buy at ₹11,875, nothing happens straight away: your order joins the bid side between ₹11,880 and ₹11,870 and waits. You are a maker because you added liquidity. If you place a market buy for 4 SOL, you take the 3 SOL at ₹11,890 and 1 SOL at ₹11,900, paying ₹47,570 in total, an average of ₹11,892.50. You are a taker because you removed liquidity. The difference between the two order types is covered in limit order vs market order in crypto.
When a market order consumes more than the top level, the average price worsens. That cost is slippage, explained with numbers in what is slippage in crypto.
Orders at the same price are usually filled in the order they arrived ("price-time priority"). So if you place a limit bid at ₹11,880 when 4 SOL are already bid there, those 4 SOL must fill before yours does.
The depth chart
Most apps also show a depth chart: two stepped curves, green rising to the left for bids and red rising to the right for asks. The height at any price shows the cumulative amount you would have to buy or sell to push the price that far. A steep curve near the middle means lots of liquidity close to the current price; a flat curve means the price can move a long way on a small order. Our guide to reading candlestick charts covers the price chart that usually sits beside the book.
What the order book can tell you
- How liquid the pair is. A tight spread and deep levels mean you can trade size cheaply. Big INR pairs such as BTC/INR and USDT/INR are usually far deeper than small altcoins.
- Your likely fill price. Before a large order, add up the amounts at each level to see where your average will land.
- Where visible interest sits. Clusters of bids below the price or asks above it show where many traders have placed orders.
- How the market reacts to news. In fast moves, market makers pull orders and the spread widens. That is a signal to slow down.
What it cannot tell you
- Walls can vanish. A huge bid or ask may be placed to influence other traders and cancelled before it fills. This behaviour is called spoofing and is banned in regulated markets, but it is hard to rule out.
- Hidden orders. Some exchanges allow iceberg orders that show only part of their size.
- Other venues. Each exchange has its own book. A thin book on one Indian exchange does not mean the global market is thin, and prices can differ between exchanges. Our crypto price in India explained guide shows why INR prices can differ from global ones.
Order book vs instant-buy screens
Many Indian apps offer a simple "buy" screen where you enter a rupee amount and get coins at a quoted price. Behind that screen, the app either routes your order into an order book or quotes you a price with a margin built in. Pro or "exchange" modes show the full order book and let you place limit orders, which often costs less for larger trades. See how to start crypto trading in India and our best crypto trading platforms guide. Whichever screen you use, pick a platform on the FIU-registered exchanges list.
Order books on DEXs
Most decentralised exchanges do not use order books at all. They price trades from a liquidity pool using a formula, so there are no visible bids and asks, only a quoted price and a price impact figure. A few on-chain exchanges do run order books. Either way, the core idea is the same: the more liquidity near the current price, the less your trade moves it.
FAQ
What is bid and ask in crypto?
The bid is the highest price a buyer is currently willing to pay; the ask is the lowest price a seller will accept. You buy at the ask and sell at the bid.
What does green and red mean in the order book?
Green usually marks bids (buy orders) and red marks asks (sell orders). Colours in the trade history show whether each trade was a buy or sell taking liquidity.
What is a buy wall in crypto?
A buy wall is an unusually large bid at one price. It may slow a fall, but it can be cancelled at any time, so it is not a guaranteed floor.
Why is the spread wide on some coins?
Few buyers and sellers are active, so there are gaps between price levels. Wide spreads mean higher hidden costs, especially for market orders.
This article is AI-assisted, educational and general in nature. It is not financial advice and never a guarantee of profit. Every trade is at your own risk on your own exchange. See our risk disclosure and editorial policy.
