What Is Slippage in Crypto? Price Impact, Tolerance and What It Costs

Price impact is arithmetic, and no setting removes it

A constant-product pool keeps x × y fixed. Put Δx of the first token in and the pool must hand back enough of the second to restore the product, which works out to Δy = y × Δx ÷ (x + Δx). Divide by Δx and your average price is y ÷ (x + Δx), while the marginal price before you traded was y ÷ x. The shortfall is therefore 1 − x ÷ (x + Δx) = Δx ÷ (x + Δx), which depends on one thing only: how big your trade is relative to the reserve you are trading into. Nothing about your wallet, your gas price or your patience appears in that expression.

The cost in money behaves very differently from the cost in percent. Impact is roughly proportional to trade size, so the money you lose is proportional to size squared: value × f² ÷ (1 + f), where f is your trade as a fraction of the reserve. That is why the table climbs the way it does. Going from 0.1 percent of the pool to 10 percent multiplies the trade by 100 and the cost by more than 9,000 — from $2 to $18,182. It is also why splitting one large trade into several smaller ones does not help on a single pool: the pool moves after each slice, so the slices execute at progressively worse prices and the total is very close to the one-shot cost. Splitting only helps when the slices go to different venues, or when time passes and arbitrage refills the pool between them.

Slippage tolerance is a different thing entirely

The tolerance box in a swap interface sets a minimum output: if the transaction would return less than the quote minus your tolerance, it reverts and you keep your tokens minus the gas. It exists because a blockchain transaction is not instantaneous — between the moment you sign and the moment your trade lands in a block, other people trade, and the pool you were quoted against has moved. Tolerance is protection against that delay. It is not a discount, a negotiation, or a limit on how much the pool charges you.

Both extremes cost you. Set it too tight and a trade with 5 percent price impact simply reverts against a 0.5 percent tolerance — you pay gas for nothing and try again. Set it too loose, say 20 percent on a thin pool, and you have publicly announced how much you will accept losing: a searcher can buy ahead of you, let your trade push the price up, and sell into it, pocketing the difference. That sandwich is not a bug, it is the documented economics of a public mempool, and your tolerance setting is the size of the slice. A workable habit is to read the interface's price impact estimate first, then set tolerance a little above it — enough to survive normal block-to-block movement, not enough to fund a sandwich.

What actually reduces the cost

Only two things move price impact: trading smaller, or trading against more depth. The first is under your control immediately — if a trade is 5 percent of the pool, it costs 4.76 percent, and the same money spread over three days into a pool that arbitrage keeps refilling costs a fraction of that. The second is a matter of routing. An aggregator that splits your order across several pools is genuinely reducing impact, because each pool sees a smaller f. A stablecoin-specialised curve holds far more depth near parity than a constant-product pool of the same size, which is why a large stablecoin swap on the right venue can cost single-digit basis points where a general pool would charge whole percent.

Keep the swap fee separate in your head from everything above. A 0.30 percent pool fee on a $100,000 trade is $300 and it is charged whatever the depth; the $4,762 of price impact on that same trade is fifteen times larger and comes purely from the pool's shape. Interfaces often show one and not the other, or roll them into a single estimate, which is how a trader can walk away certain they paid 0.3 percent. Run the two numbers separately before a large trade, decide whether the pool is deep enough, and if it is not, either shrink the trade or go somewhere else — those are the only levers that exist.

Frequently asked questions

What slippage tolerance should I use?

Just above the price impact the interface is already showing you, with a small margin for movement between blocks. On a deep pair that is usually a few tenths of a percent; on a thin one the impact itself may be several percent and the tolerance has to clear it or the trade reverts. What you should not do is raise the tolerance until the trade goes through without checking why it was failing — a trade that needs 15 percent tolerance is telling you the pool is too small for it.

Is slippage the same as the trading fee?

No, and they can differ by an order of magnitude. The fee is a fixed percentage the pool takes — 0.30 percent on a classic pair, so $300 on a $100,000 trade. Price impact comes from moving the pool's price against yourself and depends entirely on depth: on the pool in the table, that same $100,000 trade suffers $4,762 of impact. On a small trade the fee dominates; on a large one the impact does, and by a wide margin.

Does splitting a big trade into smaller ones help?

Not within the same block on the same pool: each slice moves the price for the next one, so the slices execute progressively worse and the total lands very close to the single-trade cost, with more gas paid. It does help when the slices reach different pools — which is what an aggregator does for you — or when they are spread over hours or days, because arbitrage pushes the pool back toward the wider market price in between.