Why Your BTC-to-ETH Wallet Swap Quote Changes

Two pool trades can sit behind a single BTC-to-ETH swap, so the amount shown in your wallet is an estimate of a route, not a fixed exchange rate. If the pools or network fees change before execution, the ETH you receive can differ from the quote.

On a route such as THORChain’s, BTC first trades against RUNE, then RUNE trades against ETH. You do not handle RUNE yourself, but conditions in both pools affect your final output. A thor swap is one way to make this route; the fuller mechanics depend on the service and route your wallet uses.

What does a BTC-to-ETH quote include?

A quote estimates how much ETH will reach your destination address after the route’s costs. It usually combines the current exchange rate, the price impact of your trade, protocol fees and the destination-chain fee.

Price impact is the change your order causes in a liquidity pool. A pool holds both assets available for swaps. When your BTC enters the pool, its balance shifts; the larger your trade compared with the pool’s depth, the more that shift can affect the rate. The second pool then sets the RUNE-to-ETH leg.

That means the displayed market price is only a reference. The swap uses the prices available in its route, and a wallet may show an estimated output, a minimum output, or both. The minimum output is the least you have agreed to receive under the swap’s slippage setting.

Why can the estimated ETH change before I confirm?

Pool prices move as other people trade and as arbitrageurs bring pool rates closer to prices on outside markets. If either pool changes between your wallet’s quote and execution, the route can return a different amount of ETH.

Your trade size matters too. A larger order uses more of the available liquidity and can cause greater price impact. A thinner pool may have a bigger effect on your quote than a deeper pool, even when the two show similar starting rates.

Fees can shift as well. A cross-chain swap involves an incoming transaction on Bitcoin and an outgoing transaction on Ethereum. Bitcoin transaction fees affect the cost of sending BTC; Ethereum network conditions affect the cost of sending ETH. The route may also charge liquidity and protocol fees, which can be deducted from the output.

Time adds another variable. Your BTC transaction needs to be observed and confirmed before the swap proceeds. During that wait, pool prices can move. Some routes split a large swap into smaller trades over time to reduce price impact, but that can make completion slower and expose later portions to later prices.

How should you compare two wallet quotes?

Compare the ETH you are likely to receive after fees, not just the headline rate. A wallet may choose a different route or include costs differently, so two estimates for the same BTC amount may not be directly comparable at first glance.

Check these details before you decide:

• Expected output: Compare the estimated ETH amount after the listed fees.
• Minimum output: Check how much ETH the swap guarantees under its slippage limit, if shown.
• Route and fees: Look for the assets and pools involved, plus any network, liquidity or service fees.
• Time and network: Check whether the route executes in one go or over time, and account for confirmation delays.

A lower displayed fee does not always mean a better quote. A route with weaker liquidity could offer less ETH after price impact, even if its separate fee line looks smaller. What matters for your decision is the net amount and the conditions attached to it.

What can you do when the quote changes?

Review the updated output before you approve the transaction. If the difference is material, pause and get a fresh quote; do not assume the earlier estimate still applies.

1. Confirm that the source asset is native BTC and the destination is the ETH asset and network you intend to receive.
2. Review the estimated output, minimum output, route and all listed fees.
3. Check the slippage limit and any expiry or execution-time details shown by the wallet.
4. Approve only if the minimum you could receive is acceptable to you.

Slippage settings involve a trade-off. A tight limit can protect you from receiving much less than expected, but the swap may fail or need a new quote if prices move beyond it. A loose limit gives the route more room to execute, while accepting a wider range of outcomes.

For most readers, the useful habit is to judge the net ETH and the minimum output together. Quotes change because trades meet live pools and live networks; a careful review lets you decide whether the route still suits you before committing your BTC.