What a swap slippage check actually measures
A slippage check scores a supported swap route on the components that quietly widen the gap between the price you expect and the price you get: expected route leak in basis points, slippage versus the mid quote, gas, and the venue and route assumptions behind the figure. Routescore turns those into a modeled expected-leak band for the exact pair and trade size you enter, with each input shown rather than rolled into one opaque number.
Slippage here means the modeled difference between the mid quote and the price a supported route would realistically clear at your notional — kept separate from the swap fee and from gas, which are surfaced on their own lines. The figure is a point-in-time model built from the launch-static route catalog and public signals, scoped to the venue and route it names. Unsupported tokens, chains, and exotic routing are not silently approximated — they are marked, so a coverage gap never reads as a clean result.
- Expected route leak in basis points, shown as a modeled band rather than a single hard figure.
- Modeled slippage versus the mid quote, separated from swap fee and gas.
- The venue and route assumptions the figure depends on, named on the artifact.
- Unsupported pairs, chains, and routing flagged explicitly, not approximated.
How to read the modeled leak band at different trade sizes
The leak band is a range, not a promise of a single outcome. A small trade on a deep USDC → WETH pool sits near the tight end of the band; the same pair at a larger notional pushes toward the wide end as depth thins and price impact grows. Reading the band means watching where your trade size lands inside it, not fixating on the midpoint.
Move the trade-size slider and the band shifts in front of you: slippage and expected leak scale with notional, so a route that looks clean at $1k can grade very differently at $100k. Try the sample USDC → WETH scenario at $10k to see how the modeled leak and slippage move as you change size — and how a lower-leak supported route can pull the band tighter for the same pair, without Routescore ever touching your wallet.
When the modeled figure is enough — and when it is not
The modeled leak band is decision support for supported routes at a point in time. It is enough when you are comparing route scenarios, sizing a trade, or keeping a record of why you leaned one way — the kind of pre-decision context where a modeled band beats a gut guess. It is not a quote, and it is not a guarantee of execution quality.
It is not enough when conditions move after the model was built: live mempool state, a fast-moving price, depth that changed since the catalog read, or any unsupported token, chain, contract, or bridge risk — all named on every artifact as out of scope. When you act, you confirm the live quote and slippage tolerance in your own venue, with your own settings. Routescore stays read-only and non-custodial throughout and does not execute, route, or hold the trade.
From a slippage check to a reviewable decision record
A slippage check is worth more when it leaves a trail. Save the scenario and you get a decision record that captures the pair, notional, modeled leak band, slippage, model and feature versions, source freshness, caveats, and confidence state — the full basis for the number, not just the number. The sample USDC → WETH report at /reports/usdc-weth-10k is exactly that shape, made public.
Later you can attach an outcome label and review whether the modeled band held at that size. That loop — run a check, save the record, review the outcome — is the part that compounds: it turns one slippage check into calibration evidence that tightens the methodology over time, in the open, instead of by assertion.