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How a DEX aggregator chooses your route

An aggregator compares pools across a network, splits the trade if that pays better, and returns one quote. Here is what it optimises and what it cannot see.

By FBT Swap · 5 October 2026

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        Inputs to the route
        Pool reserves, pool fee tier, hop count and estimated gas
      
        Split routing
        Used when reduced price impact outweighs the extra gas
      
        Quote lifetime
        Seconds — reserves change with every block

FBT Swap

What you should know

A decentralised exchange is a single pool of two tokens. An aggregator is the layer above it that asks many pools the same question — how much of token B do I get for this much of token A — and returns the best answer it can assemble.

That assembly is the interesting part. The best route is often not one pool but several, used in parallel or in sequence, because every pool charges a price that worsens as your trade grows relative to its depth.

What the aggregator is actually comparing

For each candidate path the router simulates the trade against current pool reserves and subtracts the pool fee, then subtracts an estimate of the gas each extra hop costs. A two-hop route through a deeper pool can beat a direct one-hop route, and on a cheap network it usually does; on Ethereum mainnet the gas for that second hop can erase the gain entirely.

This is why the same pair quotes differently on different networks. It is not that one chain has a better price — it is that the gas cost of complexity changes which route wins.

Splitting one trade across several pools

Every automated market maker gives you a worse rate the more you buy, because you are moving along a curve. Splitting 40% of the order into one pool and 60% into another keeps both trades near the shallow end of their curves, and the combined output beats either pool alone.

Split routing only pays when the saved price impact exceeds the extra gas. Below a certain trade size the router stops splitting, which is why small swaps often show a single simple path.

Why the quote changes between pages

A quote is a snapshot of pool reserves at a block. Other people trade in the blocks between your quote and your signature, so the reserves move and the output moves with them. That is what slippage tolerance exists to absorb.

A quote that never moves would be a lie about a live market. FBT Swap re-requests the route before you sign and shows the new figure rather than submitting a stale one.

What the router cannot see

It cannot see a token that charges a fee on transfer, unless the simulation catches it, so a quote for a tax token can overstate what lands in your wallet. It cannot see what the next block will contain, so it cannot promise the price. And it cannot judge whether the token is worth owning.

FBT Swap asks public aggregators on the selected network, shows the route, the price impact and the 0.70% platform fee, and hands the transaction to your wallet. The signature — and the decision — stay with you.

At a glance

Inputs to the route

Pool reserves, pool fee tier, hop count and estimated gas

Split routing

Used when reduced price impact outweighs the extra gas

Quote lifetime

Seconds — reserves change with every block

Platform fee

0.70% of the input, shown in the quote before you sign

FAQ

Frequently asked questions

Clear answers before you decide.

Does an aggregator always find the best price?

It finds the best price among the pools and paths it queries at that moment. A pool it does not index, or liquidity that appears a second later, is invisible to it. "Best available in this query" is an accurate description; "best possible" is not.

Why does the route have three hops for a simple pair?

Because the direct pool was too shallow for your size. Routing through a deeper intermediate token — usually a stablecoin or the wrapped native coin — costs more gas but less price impact, and the router only chooses it when that trade is favourable.

Can I force a specific pool?

Not through this interface. FBT Swap submits the aggregator route that quoted best. If you need a specific venue you would interact with that protocol directly, and you would be responsible for the route quality yourself.

Risk notice

Crypto assets are volatile and on-chain transactions cannot be reversed. You can lose money, including all of it. Nothing here is financial advice.