What makes two swap sites offer different amounts for the same pair

05 September 2026

The short answer: two swap sites quote different amounts for the same pair because each site pulls liquidity from a different pool (or set of pools), and each pool has its own ratio of tokens, its own fee structure, and its own depth.

A swap site does not hold its own inventory of tokens. It is an interface that connects you to one or more liquidity pools. When you ask for a quote, the site queries the pools it is configured to use. If site A uses a pool with 100 ETH and 300,000 USDC, and site B uses a pool with 10 ETH and 30,000 USDC, the ratios are the same - but the price impact of your trade will be larger on the smaller pool. That difference alone can change the quoted amount by a noticeable fraction.

Liquidity depth is the primary driver. In a constant-product automated market maker (the type most swap sites rely on), the price you receive depends on the size of your trade relative to the size of the pool. A small trade on a deep pool moves the price very little. The same trade on a shallow pool moves the price more, and you get fewer tokens out. Two sites that route to pools of different depths will therefore give you different quotes for the identical trade.

Fee tiers also vary. Many liquidity pools charge a fee per swap - typically 0.05%, 0.30%, or 1.00%. Some pools charge a flat fee; others charge a dynamic fee that changes with volatility. One swap site might route your trade through a low-fee pool (0.05%), another through a standard-fee pool (0.30%). The fee is deducted from the output. That difference alone explains a 0.25% gap in the quoted amount.

Some sites aggregate multiple pools. A swap site that splits your trade across three pools will often beat a site that uses only one pool, because the aggregator can take advantage of the best price in each pool for the portion of the trade it sends there. But aggregation is not free - the aggregator charges a small fee (often 0.05 - 0.10%) for the service. A non-aggregating site may show a worse price before fees but a better price after fees, depending on the trade size.

Slippage assumptions differ. When you enter a trade on a swap site, the site calculates a quote based on current pool reserves. But that quote is only valid for a short window - typically 10 to 30 seconds. If the site’s quote engine assumes a different slippage tolerance than yours, or if it refreshes at a different rate, the number you see will differ from another site’s number. One site might show the best possible price at the instant of the query; another might show a price that already accounts for a 1% slippage buffer.

Front-end rounding and display logic. Some sites round the output to a fixed number of decimals. Others truncate. A difference of 0.0001 tokens in the display can make two quotes look different even when the raw amounts are identical. This is cosmetic, but it happens.

The network fee is not included in the quote. The quote shows the amount of output tokens you will receive after the swap fee and the pool’s internal fee. The network fee (gas on Ethereum, transaction fee on other chains) is separate. It is added on top. That is why the hub page “What a crypto swap actually costs” is worth reading next - it explains the full sequence of deductions between the quote and what lands in your wallet.

In practice, the difference between two swap sites for the same pair is usually small for moderate trades on deep pools. For large trades or illiquid pairs, the difference can be large. The only reliable way to know which site gives you more is to check both quotes at the same moment. Prices move. Liquidity shifts. The site that was better five minutes ago may not be better now.

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