Swap and read the fee
The swap panel shows the fee before you sign. This page explains each line, what the fee depends on, and what happens in your transaction.
The panel, line by line
| Line | What it means |
|---|---|
| You pay | The amount you send in. Swaps are exact-input: you choose what you pay and the pool tells you what you get. |
| You receive about | The quote from Uniswap’s own Quoter, which runs the real swap, hook included, without sending it. It already has the fee and the Treasury’s share taken out. |
| Fee the hook would charge now | The total fee the hook would set for a swap in the next block, from the pool’s current memory. It is never below 0.05% or above 0.41%. Next to it: how far the model expects the price to move in the next minute. |
| of which to liquidity providers | The part of that fee that stays in the pool and is shared by the people who provided liquidity. |
| of which to the Treasury (10%) | The part the hook mints to the Treasury. It is a fixed share of the fee, set when the hook was deployed. See Treasury, buyback and burn. |
| Price | What the quote implies per unit, after the fee. |
| Pool price | The pool’s own price, and how much less this swap gets than that: the fee and the price impact together. |
| You receive at least | The quote less the slippage you allow. If the swap would return less than this, the transaction fails instead. |
| Slippage | How much worse than the quote you accept. If the result would be worse, the transaction fails instead. |
What decides the fee
Not your trade. The fee is set from what the pool remembers about its recent price moves: how far the last few moved it, how long ago and how often, which way the price has been leaning. Only moves of 3 ticks or more from the last record count, so a swap of one wei, or a flicker between two ticks, changes nothing. A pool that has been quiet charges close to the floor (0.05%). After a burst of big moves it charges more, up to the cap (0.41%). A static pool would charge 0.30% either way.
On a swap of 1,000 tokens, that is 0.52 tokens at the floor, 1.5 tokens in the middle of the range (a model output of about 520) and 4.1 tokens at the cap, against 3 tokens in a static 0.30% pool. Whether you end up paying less or more than in a static pool depends on when you trade.
Approvals, once
The first time you swap a token you are asked for two approvals, which are normal Uniswap v4 practice: your token allows Permit2 (Uniswap’s shared approval contract), and Permit2 allows the Universal Router to spend it for 30 days. After that, each swap is a single transaction. Both approvals are for the tokens of this pool only; you can revoke them at any time from your wallet or an allowance-checking tool. ETH needs neither: it is sent with the swap, and whatever the swap does not use comes back.
After you swap
The result box shows what you paid, what you received and the fee the hook logged in its Reflex event, next to the one it previewed. The two can differ slightly, because the fee is set from the block your swap lands in. Your swap then shows up on Live, and on Verify you can recompute its fee in your browser from the chain’s own data.
The fee is not the only cost
A swap also moves the price (price impact), which depends on your size against the liquidity at the current price. The quote already includes it. If a swap would move the price a lot, split it or trade a smaller amount.
Practical tips
- The preview refreshes every few seconds. If the fee is much higher than usual, the pool has just moved; the quiet time since the last move counts, so the fee tends to come down again as time passes without a new one.
- Use 0.5% slippage on calm pools. 1% is a safe default. Raise it only if swaps keep failing.
- On an exact-input swap, the Treasury’s share is taken from the token you receive, so the quote already shows what is left for you.