How to Read a Bitcoin Order Book and Market Depth Chart
Learn what bids, asks, spread and cumulative depth mean, then read them directly in the free cryptonabs BTC/USDT viewer.
A Bitcoin order book is a live list of resting buy and sell orders for one trading pair on one venue. Bids are buy orders below the market, asks are sell orders above it, and the difference between the best bid and best ask is the bid-ask spread. A market-depth chart turns those price levels and quantities into a shape that is faster to scan than a long table.
You can follow the steps below in the free live Bitcoin order book. The public viewer currently shows BTC/USDT from its named source, needs no exchange account or API key, and cannot place a trade.
What Level 2 order-book data shows
Market-data labels vary between venues, but Level 2 or market by price normally means aggregated visible quantity at each price level. It is deeper than the best bid and best ask, but it does not expose individual order IDs, account owners or the reason an order was placed. True market-by-order data is commonly called Level 3 and is not part of this viewer.
The Binance Spot diff-depth stream used to maintain the local book sends changed bid and ask price levels. Its quantity is the new absolute quantity for that price, not an amount to add to the old value; zero removes the level. Sequence IDs connect those changes to a finite REST snapshot. The official local-order-book procedure also warns that levels beyond the snapshot limit remain unknown until they change.
| Data view | What it can show | What it cannot show |
|---|---|---|
| Candles / last value | Executed-trade prices aggregated over time | The current resting size at each bid or ask |
| Top of book | Best bid, best ask and their spread | How much size rests farther from the market |
| Level 2 depth | Visible quantity grouped by price level | Individual orders, hidden size, ownership or intent |
| Level 3 depth | Individual order events when a venue supplies them | Information that the source venue never publishes |
1. Check the source, pair and timeframe
Start with the controls above the chart. Source identifies the exchange feed, Pair identifies the exact base and quote assets, and Timeframe controls the candle aggregation. BTC/USDT on one exchange is not the same dataset as BTC/USD or a cross-exchange market.
The candles and order book also represent different time concepts. Candles summarize executed trades over a period. The order book is a rapidly changing snapshot of orders that are currently resting and may be changed or cancelled before execution.
2. Find the best bid, best ask and spread
The highest bid is the nearest visible buyer below the market. The lowest ask is the nearest visible seller above it. Their difference is the spread. A narrow spread describes the current gap between these two quoted prices; it does not guarantee that a larger order can execute at either displayed price.
In the cryptonabs chart, bids and asks meet around the current-price region on the right side. The separate order-book rows expose exact visible price and quantity values. The curve is a visual summary, so use the rows when an exact level matters.
3. Read quantity and cumulative market depth
Each raw order-book level has a price p and a resting quantity q. With Cum Depth enabled, cryptonabs sorts asks outward from the best ask and bids outward from the best bid, then computes the running quantity at each level:
This answers a precise descriptive question: how much displayed resting size lies between the best quote and that price level in the currently received book? Turning Cum Depth off shows the quantity at each individual level instead.
4. Understand the cryptonabs Order Hull
Order Hull is the name of the market-depth overlay drawn beside the candles. Price determines vertical position. Quantity determines how far a band extends left from the right-hand price anchor. In cumulative mode, farther price levels normally include all nearer quantities, so the outline grows as it moves away from the spread.
Several nearby price levels can map into the same few-pixel vertical band. The renderer retains the applicable depth for that band and scales widths against the visible reference depth. It closes visual gaps between real neighboring bands, but it does not extend the outermost bid or ask to a chart boundary where no level was received. That is why the Hull is a stepped depth curve rather than two rectangles filling the plot.
Absolute anchoring places levels on the same price scale as the candles. Relative anchoring concentrates on depth near the current price. Zooming or choosing a long candle timeframe can compress the book into a small part of the much larger historical price range; it does not mean the order book contains only two levels.
5. Treat walls as changeable orders, not predictions
A visibly wide section is often called a buy wall or sell wall. It means the received snapshot contains more resting size around those prices than around thinner sections. Orders can be amended, cancelled or executed, and the view covers only one selected venue. A wall therefore is neither confirmed support or resistance nor a forecast of the next price move.
6. Check freshness before interpreting the chart
The large value above the chart belongs to the selected source, pair and timeframe. Connection status, loading state and continuing chart progress matter as much as the displayed number. A browser can retain old pixels after a disconnect, which is why cryptonabs reconnects and reloads state when a restored tab resumes.
For a fuller reliability checklist, read the limits of live crypto order-book data. The separate guide to restored browser tabs and live charts explains why an HTTP response alone cannot prove that a chart is fresh.
7. Use a cautious crypto order-book analysis workflow
A useful analysis is a repeatable observation, not a directional verdict. Keep the source, pair, measurement range and time fixed long enough that another reader could understand what you compared. Then separate what the book displayed from what trades actually executed.
- Fix the identity and time. Record the named venue, exact pair, observation time, selected timeframe and connection state. Do not combine BTC/USDT with BTC/USD or silently compare different exchanges.
- Start with exact quotes. Read the best bid and best ask from the rows, calculate the spread, and note the current value separately. The Investor.gov definition treats the spread as the difference between the highest bid and lowest ask.
- Compare a fixed range. Measure cumulative bid and ask depth over the same percentage distance on both sides, such as 0.5% from the midpoint. Whole-book totals are misleading when the visible price ranges differ.
- Separate displayed interest from execution. Resting orders are not executed trades. Compare the current Hull with the candle path, but do not claim that a wall caused a move merely because both appeared near the same price.
- Re-observe persistence and freshness. Note whether a level remains, changes, trades or disappears across later live updates, and confirm the chart is still progressing. One retained screenshot cannot prove the sequence that produced it.
Depth is only one component of liquidity. CME Group's liquidity-method review cautions against treating book depth in isolation as a complete liquidity measure. Fill quality, price impact, executed volume and market conditions answer different questions.
A cancellation alone does not prove spoofing. The CFTC's official interpretive guidance distinguishes legitimate cancellation from an order entered with intent to cancel before execution. A public depth chart cannot establish a participant's intent, so cryptonabs describes visible changes without labelling a person or order as manipulative.
What a depth chart does not tell you
- It does not show every exchange, pair, hidden order or future order.
- Displayed liquidity can disappear before any execution reaches it.
- Width is relative to the current view and is not a cross-market liquidity score.
- The Order Hull is a depth curve, not a historical liquidity heatmap.
- The viewer does not predict direction or provide buy, sell or hold recommendations.
- cryptonabs.com does not route orders, hold assets or manage portfolios.
See the market-data and risk notice for the complete public boundary. This article was prepared with AI assistance and reviewed against the implemented viewer behavior before publication.