What Slippage Is, and Why You Got Fewer Tokens Than the Quote

You entered one ETH, the interface said you would receive some number of tokens, you confirmed, and fewer arrived. Nothing went wrong. What you were shown was a quote, and a quote on an automated market maker is a calculation about the pool as it stood a moment ago.

Why a quote is a prediction

A pool holds two assets and prices them against each other by ratio. Buying moves the ratio, which moves the price – that is the whole mechanism, and it applies to your own order too. The quote you see is what you would get if nothing changed between the click and the block. Something almost always changes.

Cause one: your own size

The larger your order relative to the pool, the more of the price movement is yours. In a deep pool a modest buy barely registers. In a pool with a few ETH of liquidity the same buy can be most of the volume in that block, and you are quite literally paying yourself a worse price as you go. This is why reading liquidity before sizing matters more than reading the chart.

Cause two: everyone else

Other buyers and sellers are in the same block. On a new launch there may be hundreds of them, all of whom saw the same chart you did. Their orders move the pool between your quote and your fill, and on a token that is moving quickly this alone can be the whole difference.

Cause three: MEV, and why this chain is different

On a typical public chain, pending transactions sit in a mempool where anyone can read them. A bot that sees a large buy can place its own buy in front of yours, let your order push the price up, and sell into it. That is a sandwich, and it is a real cost that looks exactly like ordinary slippage on your screen.

Robinhood Chain has no public mempool, which removes the simplest version of that attack – there is no queue to read. It is worth knowing this rather than assuming, because much of the advice written about slippage assumes a mempool that is not there. It does not make execution free, and it does not help with the first two causes at all.

Setting tolerance properly

1. Treat tolerance as the worst price you will accept, not the price you expect.
2. Start low. If the transaction fails, that is the pool refusing your order at a price you said you would not exceed – which is the setting working.
3. Raise it deliberately and by small amounts, knowing that each step widens what you might pay.
4. On a thin pool, size down instead of loosening tolerance. The tolerance does not make the pool deeper.
5. Check the pool on Dexscreener before a large order rather than after a bad fill.

Where tools help

Terminals with MEV protection route the order so it is harder to front-run, which addresses the third cause. Definitive splits large orders across time and venues with TWAPs, which addresses the first. Neither does anything about the second, and no tool makes a thin pool deep.