Why Swap Output Can Differ From the Quote

Swap output variance is the difference between the amount a swap quote shows and the amount you receive when the trade completes. The quote is an estimate based on conditions at that moment. By the time a transaction reaches the pools that handle it, prices or available liquidity may have changed.

The term describes an outcome, not one specific fee or protocol feature. A small gap can come from normal trading costs. A larger one can mean the route was thin, the market moved, or the swap took longer than expected.

What changes the amount a swap returns?

Pool depth is one key factor. A liquidity pool holds tokens people can trade against. A large swap uses more of that pool and shifts its token balance, so each part of the trade gets a slightly different rate. This price movement is called price impact.

A route can add more steps. For example, a swap between two tokens may pass through a third asset if there is no direct pool. Each step uses a pool with its own depth and rate. On THORChain, a swap between two non-RUNE assets uses two pool swaps, with RUNE moving between them inside the network. A guide to thor swap route checks explains what to look at when choosing a destination chain.

Network fees and pool fees also reduce the amount that arrives. They are part of the expected cost, though a quote may show them separately from the estimated output. The exact display varies by interface.

How is variance different from slippage?

Slippage is the change in a trade’s rate between the quote and execution. Output variance is the broader gap between expected and received amounts. It can include slippage, fees, price impact and route changes.

Some apps let you set slippage tolerance, the largest rate change you will accept. This usually sets a minimum output: if the trade would return less, it fails or gets reverted. A tight limit protects the expected amount, but a trade may fail if prices move quickly. A loose limit makes execution more likely, but permits a worse result.

Why can two quotes for the same swap differ?

Quotes are snapshots. They can differ if pools have changed, if one service finds a different route, or if fees and token prices have updated. Even the same route can return a different amount moments later as other swaps change its pool balances.

For a simple example, imagine a quote estimates 100 tokens out. If the pool shifts before execution, the swap may return 98. A minimum output of 99 would stop that trade; a limit of 97 would allow it. The actual amounts depend on the token, route and interface.

What should you check before swapping?

Compare the minimum output and total fees, then check the route and destination asset. For a larger trade, compare quotes again just before confirming. A route with more steps can reach a better pool, but each step adds another price and fee to account for.

• Check how much the wallet must send and the minimum it can receive.
• Look at network and pool fees, not just the headline exchange rate.
• Confirm the destination chain and receiving address.
• If the minimum output seems too low, refresh the quote or reduce the swap size.

The useful takeaway is to treat a quote as a current estimate, not a promise. The minimum output defines the amount you are willing to accept, while the route and fees help explain why the final amount may vary.