Splitting one trade across four pools sounds like overhead. On the trades where it matters, it is the difference between a good fill and a bad one.
Dario FennDeFi & Markets Lead · DeFi protocols, yield, market structure and on-chain data
A DEX aggregator queries many liquidity sources and constructs a route — often splitting the order across several pools — to minimise total cost. It wins when the trade is large relative to any single pool's depth, when the pair has no direct market, and on chains where gas is cheap enough that multi-hop routes are free. It loses on small trades on expensive chains, where the extra gas exceeds the price improvement. Always compare the quoted output, not the route.
Liquidity for the same pair sits in many places at once — several pools on one exchange at different fee tiers, other exchanges, and sometimes off-chain market makers. Executing against one of them is simple and frequently not the best available price. An aggregator's job is to find the rest.
Three techniques, usually combined.
**Splitting.** Because price impact grows faster than linearly with size, sending 40% of an order to one pool and 60% to another produces a better average price than sending all of it to either. This is the largest source of improvement on big trades.
**Multi-hop.** For a pair with no direct market, or a thin one, routing through an intermediate asset can be cheaper than the direct pool. A to ETH to B, or through a stablecoin.
**Source selection.** Including venues you would not have thought to check — a newer AMM with an incentivised pool, a stable-swap curve for correlated assets, or a private market maker quoting on request.
Size relative to depth is the dominant variable. If your order is a meaningful fraction of any single pool's liquidity within a percent or two of the current price, splitting will beat going direct, often by more than the entire fee.
Thin or unusual pairs also favour aggregation, because the difference between the best and worst route is largest exactly where liquidity is fragmented.
And cheap chains favour it structurally. On Solana, a route touching five venues costs a fraction of a cent in fees, so there is essentially no reason to swap directly — the routing is free and the improvement is not. The same holds on low-cost L2s.
Small trades on expensive chains. A multi-hop, multi-venue route on Ethereum mainnet can cost several times the gas of a single swap, and on a $200 trade that gas difference dwarfs a few basis points of price improvement. Aggregators know this and will often return a direct route for small sizes — but the wallet interface offering a one-click swap may not.
Deep stablecoin pairs are the other case. When a purpose-built stable pool holds enormous liquidity at near-zero impact, there is nothing to improve on.
Routing changes your fill; it does not by itself protect the transaction. A large swap broadcast to the public mempool is visible whether or not it is split, and sandwich attacks work the same way.
This is where intent-based execution has changed the category. 1inch Fusion replaces the ordinary swap with an auction in which professional resolvers compete to fill your order and absorb the execution risk themselves; you sign an intent rather than a transaction, and the winning resolver's incentive is to deliver the best price it can while covering the MEV exposure. For ordinary users this frequently improves realised prices more than routing alone, and it is the subject of intent-based trading.
One rule: compare the final output amount, net of gas, for your actual size. Not the route diagram, not the number of sources used, not the headline rate.
Three things to watch while doing it. The gas estimate, which varies enormously between routes and is quoted separately. Any aggregator or wallet fee — most aggregators charge nothing or very little, but wallet-embedded swap interfaces frequently add a markup approaching 1% on top of the route they use. And the positive slippage policy: some routers return unexpected surplus to the user and some keep it, which is disclosed but rarely read.
The comparison takes fifteen seconds and, on any trade above a small amount, it is the highest-return habit available in on-chain trading — which is why fee transparency and route disclosure are scored explicitly in the DEX ratings rather than treated as implementation detail.
Cheap chain, any size: use an aggregator by default. Expensive chain, small trade in a deep pair: go direct and save the gas. Expensive chain, meaningful size: use an aggregator and use an MEV-protected or intent-based route. And on anything unusual — a long-tail token, an exotic pair — check both, because that is where the spread between the best and the worst execution is measured in whole percentage points.
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