AMM swap scenario · Reviewed 2026-11-03

DEX constant-product price impact calculator

Estimate constant-product AMM swap output, fee-free reserve-curve price impact, pool fee, and modeled post-swap price from entered reserves.

Estimate a single swap against a two-token constant-product pool using reserves and assumptions you enter. This browser calculator does not connect to a wallet or fetch a quote.

Input token symbol Output token symbol Input token reserve Output token reserve Swap direction Trade amount (input token) Pool fee (%)

Enter both reserves, a trade amount and the pool fee.

The fee percentage is an assumption, not a claim about any pool. Reserves must use the same token units as the amount fields.

Method and assumptions

This model treats the pool as a v2-style constant-product pool with input reserve x, output reserve y, and x × y = k. It applies the fee to the input amount before calculating output: effective input = input × (1 − fee rate), then output = y × effective input ÷ (x + effective input). The full input, including the fee, is added to the input reserve after the swap.

Price impact here means the fee-free reserve-curve effect: compare the output the curve gives for the full input with the same input valued at the starting mid-price (y ÷ x). The fee is reported separately. The displayed execution price uses the actual fee-adjusted output. A later trade can see a different pool price because reserves have changed.

This does not estimate a v3 concentrated-liquidity route, routing across pools, price movement before execution, transaction failure, gas, or actual execution slippage. A live quote may also account for token behavior and route details that are not modeled here.

Sources

Uniswap Developers: How Uniswap Works — pool reserves, the constant-product formula, and how trade size relative to pool depth moves price.
Uniswap Support: What is price impact? — price impact as the price change directly caused by a trade and its relation to pool liquidity.

Sources reviewed 2026-11-03. Educational arithmetic only; this is not a live DEX quote, v3 estimate, or financial advice.

How it works

Enter both pool reserves, choose a swap direction, provide the trade amount in the input token, and enter an assumed pool fee. The calculator estimates output and separates fee-free price impact from the fee.

Good to know

What does price impact mean here?

The calculator compares the fee-free output from the constant-product reserve curve with the output at the pool’s starting mid-price. It reports the input fee separately and uses the fee-adjusted output for the estimated execution price.

Is this a Uniswap v3 quote or execution slippage estimate?

No. This is a simplified two-token constant-product reserve model. It does not model concentrated liquidity, multi-pool routing, price changes before execution, or live execution slippage.

Where does the pool fee come from?

You enter the fee as an assumption. Pool fees vary by protocol, pool, and version; the page does not fetch or claim a current fee for any market.

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