Relate swap size to the reserve you are adding to

For a simple constant-product pool, compare your input amount with the reserve of the token you are adding. That ratio is more informative than dividing trade value by the pool's combined TVL.

Express the size ratio

Let x be the input-token reserve, y the output-token reserve and a the amount added. In a fee-free model, output is y × a / (x + a). Relative to the initial local rate y / x, the average output-rate shortfall is a / (x + a).

Use a hypothetical pool with x = 10,000:

The ratio concerns the input reserve. A trade worth 1% of combined two-sided TVL may represent about 2% of the input-side value in a balanced pool, so the denominators are not interchangeable.

Keep the model boundary visible

The calculation follows the constant-product structure documented in the Uniswap v2 whitepaper, with fees deliberately removed for this illustration. Real quotes include the implemented fee rule, rounding and possibly several pools.

The shortfall above is an average execution-rate measure. It is not the percentage change of the final marginal pool price, which moves by a different amount.

Use the ratio as a diagnostic

A large input-to-reserve ratio signals that size effects deserve attention. It does not provide a universal impact estimate for concentrated or stable-asset curves. For those systems, active ranges or invariant parameters matter.

Identify the pool, direction and reserve state, then compare the model with a current size-specific quote. If the route uses several pools, the thin connecting pool may be more relevant than the apparent depth of the token's most visible pair.