Reading Order Book Depth and Liquidity

What an order book shows

An order book displays currently open buy and sell orders at various price levels, giving a real-time view of where actual trading interest exists above and below the current market price.

What "depth" refers to

Depth describes how much order volume exists at price levels near the current price — a market with strong depth can absorb a larger trade with less price impact, while a shallow, thin order book can be moved significantly by a comparatively small order.

Practical reading tips

• Check the volume available at the price levels closest to the current price before placing a large order.
• A wide gap between the best bid and best ask (a wide spread) can itself be a sign of thin, less liquid trading conditions.
• Depth can change quickly as orders are placed and canceled — a snapshot reflects that specific moment, not a guarantee.

What to remember

• An order book shows real-time open buy and sell orders at various prices.
• Depth describes available volume near the current price, affecting likely price impact.
• Checking depth before a large order helps estimate its probable execution impact.
• Depth varies significantly by exchange and specific trading pair.