// GLOSSARY

Fee-adjusted net price

The all-in price per contract after fees: fill price plus taker fees (and any gas) for buys. The only number that makes Kalshi and Polymarket comparable, since one charges a formula-based taker fee and the other mostly charges no exchange fee.

Quoted prices lie by omission. The number that matters is what one contract actually costs you, all fees in — the fee-adjusted net price.

Worked example

The same event trades at 44¢ ask on Kalshi and 0.45 ask on Polymarket. Buying 100 contracts on Kalshi at 44¢ incurs a taker fee of 0.07 × 100 × 0.44 × 0.56 = $1.73, rounded up to $1.73 — about 1.73¢ per contract, for a net of ~45.7¢. Polymarket at 0.45 has no exchange trading fee on most markets (your costs there are spread and Polygon gas), so its net is ~45.0¢. The venue with the worse quote wins on net price.

Why it matters

The ranking flips with price level and size — Kalshi's fee formula peaks near 50¢ and shrinks toward the extremes — so no static rule ("always venue X") works. Comparing fee-adjusted net prices per order is the core job of smart order routing, and it's the number a Mithril execution receipt reports. Full fee math in Kalshi vs Polymarket fees.