What Slippage Actually Is
Slippage is the difference between the price you expected and the price you actually got.
You see Token X at $1.00 on the order book. You hit buy. Your fill price: $1.03. That 3% difference is slippage.
It happens because the order book has limited supply at each price level. The $1.00 you saw was the best ask — but there might only be $50 worth of tokens at that price. If you're buying $1,000, you need to eat through multiple price levels.
Why Slippage Destroys Arbitrage Profits
Arbitrage profits are typically small — 1-5% on most realistic opportunities. Slippage of 2-3% on either side can wipe out the entire profit or flip it to a loss.
And here's the brutal part: you get slippage on BOTH sides. Your buy pushes the price up. Your sell pushes the price down. Double slippage on a thin order book can easily eat 5-10% total.
Spread between Gate and HTX was 17.7%. Looks amazing. But with just $100:
The spread was real. The profit was not.
How Order Book Depth Creates Slippage
Think of the order book as a stack of cups. Each cup has a price label and a certain amount of liquidity. When you pour in your market order, it fills the first cup, overflows to the next, then the next. Full anatomy in the order books guide.
$10K order: slippage ~0.001%
$500 order: slippage ~7.5%
Slippage Is Not Linear
If $100 causes 1% slippage, $1,000 doesn't cause 10%. It might cause 4%, or it might cause 15%. It depends entirely on the shape of the order book.
There's a sweet spot where profit is maximized relative to position size. Above that, slippage eats more profit than the additional size generates.
Buy-Side vs Sell-Side Slippage
Slippage happens on both legs of an arbitrage trade, but it's rarely equal.
Common pattern: the exchange with the lower price (where you buy) has decent liquidity. The exchange with the higher price (where you sell) has thin liquidity — which is exactly WHY the price is higher.
Always check both sides separately.
Slippage in Spot vs Futures
Straightforward — you're eating through real sell orders (asks) or buy orders (bids). The liquidity is what's actually posted.
Can be lower — more market makers, limit orders without token transfers. But can be worse during volatile moments — liquidation cascades, wider quotes.
For arbitrage between two futures exchanges, slippage tends to be manageable. Spot-to-spot on small exchanges is where slippage gets dangerous.
The Low Liquidity Warning
There's a scenario worse than high slippage: when the order book literally cannot fill your order at any reasonable price.
You want to sell $1,000 of Token X and the entire bid side only has $400 of total liquidity. You physically cannot sell $1,000. You'd crash the price to near-zero trying.
A 30% spread means nothing if you can't execute the sell side.
How to Manage Slippage
If your order is more than 10-20% of the liquidity within 1% of the best price, you'll experience meaningful slippage.
$50K within 1% of best ask → comfortable size: $5-10K. $500 within 1% → comfortable size: $50-100.
A scanner that shows "5% spread" without slippage data is actively misleading.
Look for tools showing order books from both exchanges, slippage calculation, and low liquidity warnings.
For futures arbitrage, limit orders don't cause slippage — but you might not get filled, and the spread might disappear.
For spot-spot arbitrage, speed matters more — you usually need market orders.
If the book is thin but has liquidity across many levels, splitting into smaller orders over a few minutes can get a better average price.
Only works if the spread is persistent and the book is being replenished by market makers.
Check actual order book depth on both exchanges. Calculate slippage at your specific trade size. Only trade if net profit after slippage, fees, and funding is still positive. The best trade is sometimes no trade at all.
Tools showing both order books with net calculation are covered in the scanner guide, and step-by-step execution of each type in the trading guide.
FAQ
What is slippage in simple terms?
It is the difference between the price you saw and the price your order actually filled at. You see a token at $1.00, hit buy, and get filled at $1.03 — that 3% is slippage.
Why did a 17% spread turn into a loss?
In the BNKR/USDT example the Gate-HTX spread was 17.7%, but sell-side slippage hit 17.408% — a thin book on the sell side. Net on $100: -$0.98.
Does slippage scale linearly with trade size?
No, it is not linear: if $100 causes 1% slippage, $1,000 might cause 4% or 15% — it depends on the shape of the book. There is a sweet spot above which profit falls.
Is slippage worse on spot or futures?
Between two futures exchanges slippage tends to be manageable — more market makers. Spot-to-spot on small exchanges is where it gets dangerous.