Price impact is the change in a pool’s quoted price caused by your trade, and it usually grows as your order takes up more of the pool’s available liquidity. Knowing how it works helps you compare swap quotes by expected output, rather than by headline price alone.
Pool depth sets how much your trade moves the price
In a common automated market maker (AMM), trades use tokens held in a liquidity pool. For a basic constant-product pool, the reserve amounts follow x × y = k: when a trade adds one token and takes out the other, the pool’s reserves change and so does the exchange rate. A larger order changes those reserves more.
For example, imagine a pool with 1,000,000 USDT and 1,000,000 USDC, both valued at about one dollar. Ignoring fees and any price movement elsewhere, a 1,000 USDT trade returns about 999.00 USDC; a 10,000 USDT trade returns about 9,900.99; and a 50,000 USDT trade returns about 47,619.05. The larger trades receive progressively less USDC per USDT because each one pushes the pool further along its pricing curve.
These are illustrative figures for one idealized pool, not a quote. A real pool charges a trading fee, and its reserves may not be balanced at one dollar. SUN.io’s SunSwap documentation explains the constant-product mechanism used by its pools; the actual formula and fee depend on the pool and protocol version.
Price impact is different from slippage and fees
Price impact comes from your order size relative to liquidity. Slippage is the difference between the output you expected when requesting a quote and what the transaction actually delivers; it can happen if pool prices change before your trade executes. A trading fee is a separate charge deducted under the pool’s rules. Quote displays can define price impact differently, so check whether the shown figure includes fees.
A route can also pass through more than one pool. For example, swapping one TRC-20 token for another may use an intermediate token if that route offers better liquidity. Each pool affects the final output, so compare the estimated amount received for the same input and check the route’s minimum output. A route with a better displayed price may still be less attractive if it adds fees or execution steps.
Compare the output for your intended order size
To compare ways to swap, enter the amount you actually plan to trade and look at estimated output, price impact, route, and minimum output together. If a quote looks poor, try a smaller order and compare the combined result, including any extra transaction costs. On TRON, smart-contract calls use Energy and transactions use Bandwidth; the TRON Developer Hub explains that available resources and account activity affect how those costs are covered.
High price impact is a reason to pause and compare, especially for a large order or a thinly funded pool. In practice, I’d compare quotes at the full intended size before deciding whether to trade all at once or in smaller portions. When that comparison involves a TRON swap, focus on the final amount you expect to receive, not just the token pair’s displayed rate.