Protect Your Swaps: Slippage & MEV
1. Core Concepts
1.1 Slippage (Slippage Tolerance)
Your execution price can drift due to volatility, pool depth, and routing.
In Swap settings you’ll see:
- Slippage (%)
- Minimum received (quote output × (1 − slippage%))
Example: You expect 1,000 tokens with 1% slippage. If the execution worsens by more than 1%, the transaction reverts to protect you.
Formula: Minimum received = quoted output × (1 − slippage%).
1.2 MEV (Maximal Extractable Value)
Others profit from your order flow:
- Front-run: They buy just before your transaction, pushing the price higher.
- Sandwich: They buy before you and sell immediately after, using your slippage to lock in profit.
- Back-run: They execute an arbitrage trade right after your transaction.
End result: You get worse trade execution, failed transactions (wasted gas), or both.
2. When Should I Adjust Slippage?
| Scenario | Starting point (guideline) |
| Stablecoin ↔ Stablecoin (deep) | 0.05%–0.30% |
| Large-cap assets (ETH/BNB etc.) | 0.30%–0.50% |
| Mid/small caps / higher volatility | 0.50%–1.00% |
| New/illiquid pools, hot memecoins | 1%–3% (use caution) |
Rule of thumb: the lowest slippage that still fills is best. Raising slippage doesn’t make a swap “faster”; it just permits worse prices and more sandwich room.
Signals to nudge up slightly (+0.1–0.3%):
- Repeated INSUFFICIENT_OUTPUT_AMOUNT or “Price impact too high”.
- Taxed tokens (buy/sell tax) — always test with a tiny amount first.
3. Why MEV Punishes “Urgent” Orders
Your transaction often enters the public mempool before inclusion. Bots can detect a large buy and:
1. Buy first (front-run),
2. Let you execute at a higher price within your slippage,
3. Dump immediately after (back-run).
4. Net effect: you hit “minimum received” or revert while paying gas.
4. KuCoin Web3 Wallet: Recommended Settings (General)
Path: KuCoin App → top bar “Web3” → bottom bar → Swap
Settings: Swap screen → Slippage (choose Smart Slippage)
1. Choose token & network: Prefer deeper liquidity (lower price impact).
2. Set slippage: Start low (e.g., 0.3%). If it fails, bump in small steps.
3. Turn on "MEV Protection"
4. Check “Minimum received” before confirming.
5. First time with a token: you’ll Approve first, then Swap. Use on-demand allowances (avoid unlimited).
6. Small → large: confirm route/taxes with a small test swap before scaling size.
Tip: If you keep failing or see high price impact on one route, try a deeper route or split the order.
5. Anti-MEV Checklist (6 Practical Moves)
1. Keep slippage as low as possible while still filling; avoid 3%+ unless truly necessary.
2. Split large orders to reduce footprint and price impact.
3. Avoid peak volatility windows when possible.
4. Prefer deeper pools/routes — less price impact, less sandwich room.
5. Approve on demand — large/unlimited allowances increase risk (not MEV itself but part of overall attack surface).
6. Verify token taxes/quirks — taxed tokens reach “minimum received” thresholds faster.
6. FAQs
Does higher slippage make swaps faster?
Not directly. Speed is mainly about network conditions, route depth, and gas.
Higher slippage just permits worse execution and increases sandwich risk. Why did my execution differ so much from the quote?
Likely rapid price moves, shallow liquidity, or a sandwich. Inspect surrounding transactions on a block explorer.
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