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DEX vs CEX, and why prices differ

Decentralised exchanges versus centralised exchanges: how each prices assets, why liquidity, fees and settlement create gaps, and what that means for arbitrage and self-custody.

6 min read

Decentralised exchanges (DEXs) and centralised exchanges (CEXs) both let you swap one asset for another, but they work in fundamentally different ways. Understanding the difference explains why prices diverge — the very thing arbitrage exploits — and why custody matters.

How each one prices an asset

Centralised exchanges

A CEX runs an order book: buyers and sellers post bids and asks, and the exchange matches them. You deposit funds, trade against the book, and withdraw. Prices are set by whoever is willing to trade right now on that specific exchange.

Decentralised exchanges

A DEX prices swaps from on-chain liquidity pools (or routes across many of them). There's no central matchmaker — a smart contract quotes you based on the pool's reserves, and the trade executes from your own wallet.

Why their prices diverge

Liquidity: deep books or pools quote tighter prices; thin ones move on small trades.
Fees: each venue and network charges differently, shifting the effective price.
Settlement: CEX trades are instant internally; on-chain trades wait for blocks and bridges.
Audience: a token popular on one chain or exchange can trade at a premium there.

Divergence is the opportunity

Because DEX and CEX prices are formed independently, they routinely disagree by a handful of basis points. That disagreement is exactly what an arbitrage scanner surfaces — buy on the cheaper venue type, sell on the dearer.

Custody: the deciding difference

The biggest practical difference isn't price — it's control. On a CEX your funds are held by the exchange while you trade and until you withdraw. On a DEX you trade from a wallet you own, so you never hand over custody. WAGMI is built around the DEX model: swaps settle to addresses you control through your own vault, and centralised-exchange prices are read as quotes so you can compare without giving up custody to look.

You don't have to choose

The best price for a given asset and size could be on either side on any given day. WAGMI's scanner ranks DEX networks and centralised exchanges on one ladder, so instead of picking a side you simply see where the asset is cheapest to buy and dearest to sell — then act in self-custody.

Key takeaways

DEXs price assets with on-chain liquidity pools and routers; CEXs use order books.
Different mechanisms, fees and liquidity mean DEX and CEX prices rarely match exactly.
DEXs keep you in self-custody; CEXs require depositing funds to trade.
WAGMI compares both, so you see the best price wherever it is.

FAQs

Which is cheaper, a DEX or a CEX?+

Neither always wins. CEXs often have deeper liquidity for major pairs and tighter spreads at size; DEXs can be cheaper for long-tail tokens or on low-fee networks. The only way to know for a given asset and size is to compare — which is what WAGMI does.

Can I keep self-custody on a CEX?+

No. Funds on a centralised exchange are held by that exchange while they sit there. DEX trades happen from your own wallet, so you keep self-custody throughout. WAGMI settles swaps to wallets you control.

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