For a first token swap, keep slippage low and raise it only if a sound trade keeps failing. Slippage is the change between the price shown before you trade and the price you get when it runs.
Slippage Sets Your Minimum Output
Slippage tolerance is the largest price change you agree to accept. It sets a minimum amount of the token you must receive for the trade to complete.
For example, imagine a swap preview estimates that 100 USDC will get you 0.05 ETH. With a 1% tolerance, the minimum output is 0.0495 ETH. These figures are illustrative; the actual quote depends on the pool and market at the time.
A liquidity pool is a shared supply of two tokens that traders swap against. In an automated market maker, a program uses the pool’s token balances to set prices. A large trade can shift those balances, so its price may be worse than the price for a small trade.
Price Impact And Slippage Have Different Causes
Price impact is the change caused by your trade size against the pool. Slippage can also happen when someone trades before yours, changing the pool after you see your quote. Uniswap Labs’ support material explains slippage as the difference between the expected and final swap price.
That distinction helps you choose what to change. If the estimated output is already poor, your trade may be too large for that pool’s available liquidity. A wider tolerance will not improve the quote; it only lets the trade finish at a worse price.
When you submit a swap, the transaction carries the minimum output. The pool checks the live price when the transaction runs. If the output meets that minimum, the swap completes; if it falls short, the swap reverts. A reverted transaction can still use network gas, the fee paid to process an on-chain transaction.
Choose A Limit You Can Accept
Start with a small tolerance, such as 0.5% or 1%, as an example rather than a universal rule. If the trade fails, check whether the token price moved or the pool is thin. Consider retrying later or reducing the trade size before accepting a wider limit.
Be especially careful with unfamiliar tokens or sudden price swings. A very high tolerance can let you receive far fewer tokens than the preview showed. The Uniswap v2 whitepaper describes how trades change pool balances, which is why execution price depends on both trade size and the pool’s state.
On Base, BaseSwap is one way to swap tokens through a decentralized exchange. Before you trade, compare the quote with the minimum output you would accept, and see the BaseSwap trading fees for more about the service. Ask yourself: would I still make this trade at the minimum shown?
Does Slippage Tolerance Add A Fee?
No. Tolerance is a limit on how much worse your received amount may be than the quote; it is not itself a charge. A swap may still have separate costs, such as a pool fee and network gas. Check the amounts shown before signing, and remember that a failed transaction may still use gas.
Should I Raise Slippage If A Swap Fails?
Only if you understand why it failed and accept the lower minimum output. A price that moved quickly may justify trying again with a carefully chosen limit. If the quote is poor because the pool has little liquidity, reduce the trade size or wait. Raising tolerance blindly can make a bad trade complete.
What If The Minimum Output Looks Too Low?
Do not sign just to make the swap go through. Compare the estimate with the amount you would be happy to receive, then lower the trade size or wait for a better quote. If the token is unfamiliar, verify its identity before trading; similar names can refer to different tokens.