Kalshi vs Polymarket Fee Math: When Each Platform Is Actually Cheaper in 2026

The Short Answer

Polymarket is cheaper on contracts priced between roughly 20¢ and 80¢. Kalshi is cheaper at the extremes — under about 15¢ or above 85¢. The reason is structural: Kalshi charges a percentage of expected profit (which peaks near 50¢), while Polymarket uses a flatter fee schedule that scales differently with price. If you primarily trade favorites or longshots, Kalshi often wins. If you primarily trade coin-flip markets, Polymarket wins.

The Per-Contract Fee Table

(Sourced from Market Math's April 2026 fee comparison; both platforms have published their schedules.) These are per-share fees, applied at trade execution. There are no withdrawal fees on either platform if you use ACH; debit card deposits on Kalshi carry a 2% fee on the deposit itself.

What This Means in Real FL Examples

Example 1 — You buy 1,000 Yes shares on the Heat to make the playoffs at 75¢. On Kalshi: 1,000 × $0.02 = $20 in fees. On Polymarket: 1,000 × $0.014 = $14. Polymarket saves you $6 on this trade. Over a season of similar contracts, Polymarket's savings compound meaningfully.

Example 2 — You buy 1,000 Yes shares on a longshot Florida governor primary candidate at 8¢. On Kalshi: 1,000 × $0.01 = $10. On Polymarket: 1,000 × $0.018 = $18. Kalshi saves you $8. The longer your tail bets, the more Kalshi's fee structure favors you.

Beyond the Headline Fees

Fees are not the only cost. Three other line items materially affect what you actually pay:

• •Bid-ask spread: On thin markets, the spread can dwarf the fee. Kalshi has tighter spreads on most US sports right now because of higher US volume.
• •Slippage: Large orders move the price against you. If you're trading 5-figure positions, you may need to leg into them across both platforms.
• •Funding costs: Money sitting on the platform isn't earning interest. If you're trading slow-resolving political markets, the time value matters.
• •Tax friction: Both platforms issue 1099s in the US, and both report to the IRS. Section 1256 treatment may apply to certain Kalshi contracts; consult a CPA.

The FL-Optimal Fee Strategy

If you trade a mix of markets, the best strategy is not to pick one platform — it's to maintain funded accounts on both and route each trade to the cheaper venue. For a Florida trader running, say, $25k of annual volume, the difference between optimal routing and 'just using one app' is typically $200-$500 per year. That's not life-changing, but it's free money once you do the setup work once.

The other reason to keep both accounts: arbitrage. When Kalshi and Polymarket have different prices on the same event, the spread is yours to capture if you can move quickly enough. Most retail won't do this profitably, but having both accounts open means you can react when the obvious mispricings appear.