The four gaps between screen and account
Every arbitrage scanner shows a spread: the same coin priced differently on two exchanges. What it usually shows is the RAW spread — the difference between two mid or last prices. Between that number and your realized profit stand four costs: taker fees on both legs, orderbook depth at your size, slippage while your orders travel, and the decay of the spread itself.
Each gap is small alone — 0.05% here, 0.1% there — but arbitrage edges are measured in the same units. A displayed 0.5% spread may net 0.1% after honest accounting, and a displayed 0.2% can easily become negative after fees and slippage. The difference between a viable strategy and an expensive hobby is whether your numbers include these gaps before you trade, not after.
Scanner spread vs your real spread
Fees, depth and funding stand between the screen and your account.
Arbitron subtracts all four fees and checks depth before every estimate.
Taker fees: the fixed toll
A two-leg arbitrage cycle is four market orders: open both legs, close both legs. At a typical 0.05% taker fee that is ~0.2% per cycle before anything else — and base-tier fees range from 0.02% (MEXC) to 0.055% (Bybit), so the toll varies by route. Any spread smaller than your four-fee total is not an opportunity; it is a donation to the exchanges.
This is the easiest gap to account for, yet most free scanners skip it because raw spreads look more exciting. Every estimate in Arbitron — the public scanner, signals, card backtests — has taker fees of both legs already subtracted, using each exchange's real fee schedule.
Depth and slippage: the size penalty
The displayed price is the best bid or ask — the price for the FIRST unit. A market order for real size walks down the book: the first $500 fills at the top, the next $2,000 a tick worse, and on a thin altcoin pair your $10,000 order can move the price by more than the entire spread you came for. This is why a spread that is real for $500 can be fiction for $10,000.
The defence is measuring liquidity at depth, not at the top of the book. Arbitron's Depth Multiplier setting checks how much volume actually sits within N levels of the book on both legs before a trade fires, and the trade worker consumes full incremental orderbooks — not periodic snapshots — so the depth picture is current to the millisecond, not to the last polling cycle.
Timing: spreads decay in seconds
Cross-exchange spreads exist because liquidity is fragmented — and they close because arbitrageurs close them. The window between "spread appears" and "spread gone" is typically seconds. A scanner that refreshes every 10–15 seconds is showing you history; by the time a human reads the row, switches tabs, and types two orders, the edge usually belongs to someone's bot.
That is the honest reason manual cross-exchange arbitrage rarely works: not because the spreads aren't real, but because human reaction time is the slowest component in the chain. Automated execution placing both legs in parallel within milliseconds is not a convenience here — it is the entry ticket.
What an honest estimate looks like
- 1
Are the fees of all four orders subtracted?
- 2
Is there depth for YOUR size, not for the first unit?
- 3
Has the pattern repeated, or did it flash once?
A number you can trust answers three questions: are fees of all four orders subtracted, is there enough depth for YOUR size, and has the pattern repeated — or did it flash once? Arbitron's estimates are backtests of the last 8 hours that replay the actual entry/exit state machine over recorded prices, count completed cycles, and report profit after fees — which is why our numbers look smaller than raw-spread scanners, and why they survive contact with reality better.
Compare for yourself: open the public scanner and look at the "Fees / cycle" column next to every estimate. If a tool you are evaluating cannot show you that column, it is showing you marketing, not opportunities.