The order book tells you whether a spread is real money or a trap. Here's how to read it.
TL;DR: The displayed price is just the tip of the iceberg. Real profit depends on order book depth at your trade size. Check top-of-book size, depth within 1%, gaps, bid-ask imbalance, and refresh rate before every trade.
An order book has two sides.
People willing to buy. Sorted highest to lowest. The top bid is the best price you can sell at right now.
People willing to sell. Sorted lowest to highest. The top ask is the best price you can buy at right now.
Between them is the spread — the gap between the best bid and best ask. On liquid pairs, this is tiny (0.01%). On illiquid pairs, it can be 1-5% or more.
If the best ask is $1.00 with 500 tokens ($500), and you want to buy $5,000 — the displayed price is irrelevant. You'll blow through that first level in the first 10% of your order.
If your order is more than 50% of the top level, expect meaningful slippage. More than 200% — significant.
Add up all the volume from the best price to 1% above (asks) or below (bids).
$50K within 1% = very liquid for a $5K trade. $500 within 1% = dangerously thin for anything over $50.
Empty zones in the order book where no orders exist. The most dangerous feature.
If your order exceeds liquidity before the gap, you jump to the next level. On a 4% spread, a single gap can turn profit into loss.
Compare total bid volume to total ask volume. $50K in bids and $5K in asks = massive buying pressure — price likely going up.
For arbitrage: if buy exchange has many asks, price might drop. If sell exchange has strong bids, price is stable for selling.
An order book is a snapshot. It changes constantly. What you see right now might not exist in 5 seconds.
On active pairs, the book replenishes quickly. On quiet pairs, what you eat stays eaten.
For arbitrage, you need to read TWO order books — one for each exchange.
Look at the ASK side — this is what you'll pay.
Look at the BID side — this is what you'll receive.
Arbitrage profit = (Exchange B bids) - (Exchange A asks) - fees - slippage. Your real average buy and sell prices determine the actual spread — not the displayed top-of-book prices.
A massive order at one price level — like $200K at $1.05 when everything else is $500-2K. Might hold the price, or might get pulled the moment someone tries to fill it.
Walls get pulled all the time. Don't rely on them.
Decent liquidity at the top few levels, then suddenly nothing: $5K, $3K, $2K... nothing until $1.05.
If your order is under $10K, you're fine. $15K — you fall off the cliff.
An order book that looks deep but is actually one market maker who will pull everything the moment you start buying. You see $50K of liquidity, place $10K — the book evaporates.
Giveaway: most depth from very few orders at evenly spaced intervals — likely a single bot.
TOKEN/USDT, +5.2% spread. Exchange A (buy) → Exchange B (sell).
The "spread" is a function of how much you trade. This is why the calculator needs your trade size.
When you see two order books, here's the fast check:
Total volume in first 5 levels on each side — more than 3x your trade size? Slippage will be small.
Any gaps bigger than 0.5% in the first 10 levels? Make sure your order doesn't reach that gap.
Bid totals vs ask totals roughly balanced? If heavily skewed, be aware of potential price movement.
Does the book look "real"? Varied order sizes at irregular intervals = real traders. Perfect sizes at perfect intervals = single bot.
Spread between best bid and ask on each exchange — under 0.1% = liquid, over 0.5% = careful.
If all five look good for your trade size — the opportunity is likely real. If any is a red flag — dig deeper or reduce size.
VoltArb calculates actual net profit using order book depth, slippage, fees, and funding rates.
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