Pool spot price vs the price of an actual swap

A pool's spot price describes the rate around its current state. Your execution price describes the average rate across the entire amount exchanged. They can differ even when no other trader acts between your quote and execution.

A small mathematical example

Assume a hypothetical fee-free constant-product pool contains 1,000 A and 1,000 B. Its initial marginal rate is one B per A. Selling 100 A increases its A balance to 1,100. Keeping the product at 1,000,000 leaves approximately 909.09 B, so the trade receives about 90.91 B.

The average rate is therefore roughly 0.9091 B per A. The original one-to-one figure was not an offer to exchange an unlimited quantity at that rate. The trade itself moved along the curve.

Uniswap's pricing explanation relates output to pool reserves and the invariant. The example above is an independent calculation with trading and network fees deliberately omitted.

A chart reference is another quantity

A chart may show a last trade, an index across markets or a value converted through another asset. Such a number can provide context without being directly executable. It may represent a different amount, venue or moment.

Compare these three statements carefully:

• “The current reference price is one B per A.”
• “This source estimates 90.91 B for a 100 A order.”
• “The completed exchange delivered 90.50 B for that input.”

The first is a reference, the second a size-specific quote, and the third a realized result. Calling all three “the price” hides the question you actually need to answer.

Which number answers your question?

For determining how many tokens a proposed order might deliver, request the full amount. For describing a completed trade, divide the actual output by the actual input using consistent units. For explaining market movement, retain the chart's own methodology. None of these quantities should silently stand in for the others.

A large gap is a reason to inspect the assumptions, not automatic evidence that the router miscalculated. It can arise from the pool curve itself, a different reference source or changed state.