How to read a crypto order book
The order book is the live list of every buy and sell order waiting to be filled. Learn to read it and you can see supply, demand and likely short-term moves before they happen on the chart.
Bids and asks
An order book has two sides:
- Bids (buyers) — orders to buy at a set price or lower. Shown in green; the highest bid sits at the top of the bid side.
- Asks (sellers, also called offers) — orders to sell at a set price or higher. Shown in red; the lowest ask sits closest to the middle.
The best bid (highest someone will pay) and the best ask (lowest someone will sell for) meet in the middle. Each row shows a price and the quantity resting at that price.
The spread
The gap between the best bid and the best ask is the bid-ask spread. A tight spread (small gap) means a liquid, actively traded market — easy to get in and out near the last price. A wide spread signals low liquidity: you'll pay more to cross it, and price can jump around.
Depth, walls and thin books
Depth is how much quantity is stacked at each price. Reading it tells you how hard the price is to move:
- A wall — a single price level with a very large quantity — can act as temporary support (big bid wall) or resistance (big ask wall). Price often stalls there.
- A thin book — little quantity near the top — means even a modest market order can push price several levels. Expect sharper moves.
The depth bars behind each row on Paperex make this visual: longer bars = more size resting at that price.
Market orders eat the book
A market order doesn't wait — it fills against the best resting orders, climbing the book until it's complete. If you buy more than sits at the best ask, you fill at the next ask up, then the next. The difference between the price you expected and the average price you got is slippage. Thin books and large orders cause more of it.
Makers vs takers
Posting a resting limit order adds liquidity to the book — you're a maker. Sending a market (or marketable) order removes liquidity — you're a taker. On real exchanges makers often pay lower fees because they help fill the book.
MY marker — that's you, as a maker, adding a bid.