The short answer
For US residents, Kalshi functions as the only fully accessible, federally regulated prediction market right now. Polymarket's global platform blocks US IP addresses. Polymarket US (QCEX) launched an invite-only waitlist in 2026 but hasn't opened enrollment broadly. Robinhood offers prediction market contracts as well, routed through Kalshi's exchange infrastructure.
If you can access both, the decision depends on what you want to trade. This guide breaks down every relevant dimension.
Side-by-side comparison
| Factor | Kalshi | Polymarket (Global) | Polymarket US (QCEX) |
|---|---|---|---|
| US access | Open | Blocked | Waitlist |
| Regulation | CFTC-regulated DCM | Unregulated (offshore) | CFTC-regulated (via QCEX) |
| Trading fees | Zero | 2% on winnings | Not yet published |
| Settlement currency | USD (bank / debit) | USDC (crypto) | USD |
| Minimum deposit | $1 | None (wallet-based) | TBD |
| Sports markets | Yes — World Cup, NBA, NFL, MLB, NHL | Yes — global coverage | Limited at launch |
| Political markets | Yes — elections, policy | Deep — highest liquidity | Yes |
| Economic markets | Yes — Fed rate, CPI, GDP | Limited | TBD |
| Liquidity (US) | High — primary US venue | N/A for US traders | Early-stage |
| Mobile app | iOS + Android | iOS + Android | TBD |
| API access | Yes — WebSocket + REST | Yes — CLOB API | TBD |
| KYC required | Yes | No (crypto wallet) | Yes |
Fees: Kalshi wins outright
Kalshi charges zero trading fees. Revenue comes from the bid-ask spread. On liquid markets the spread runs tight — often one or two cents on a dollar-priced contract. Polymarket Global charges 2% on winnings, which compounds badly on high-frequency trading. On a $0.90 contract resolving YES, that fee eats a meaningful fraction of your edge.
For traders applying Kelly criterion sizing, fees matter directly — they shift the break-even probability. Use the implied probability calculator to see how fees change your effective break-even on any contract.
Legal status: the US access problem
Kalshi holds a CFTC Designated Contract Market license — the same regulatory category as the Chicago Mercantile Exchange. Trades on Kalshi carry the same federal legal protection as futures contracts. This matters: positions can't disappear, the platform can't block withdrawals without regulatory scrutiny, and dispute resolution has a federal path.
Global Polymarket operates offshore and blocks US IP addresses. Using a VPN to access it as a US resident creates legal and tax complexity that most traders should avoid. The platform has previously been fined by the CFTC.
Robinhood routes prediction market contracts through Kalshi's exchange infrastructure under Robinhood Derivatives LLC, a registered FCM. Functionally, trading on Robinhood and trading on Kalshi directly access the same liquidity pool.
Market depth: depends what you trade
Kalshi leads on US sports and economic markets. World Cup 2026 group winner and match markets carry meaningful depth — enough for $50–$500 positions without significant slippage. Fed rate and CPI markets run deep year-round.
Global Polymarket historically held the deepest liquidity on political and crypto markets — particularly US presidential elections and major crypto price targets. That advantage doesn't help US traders who can't legally access the platform.
Settlement: USD vs crypto
Kalshi settles in USD via bank transfer or debit card. No crypto wallet required. Withdrawals process within one to three business days. For traders who want prediction market exposure without crypto infrastructure, Kalshi removes that friction entirely.
Polymarket Global settles in USDC on the Polygon network. Depositing and withdrawing requires a crypto wallet and introduces gas fee exposure and stablecoin de-peg risk, however small.
Which to use
Start with Kalshi. Federal regulation, zero fees, USD settlement, and the deepest US liquidity make it the default choice. Robinhood functions as an alternative interface to the same markets — useful if you already hold a Robinhood account. Watch Polymarket US (QCEX) for when open enrollment begins; the competitive pressure may improve market depth across both platforms.
Before you trade: size your positions correctly
The most common mistake on prediction markets isn't picking the wrong outcome — it's sizing positions incorrectly relative to your edge. A contract trading at 65¢ doesn't mean "bet everything if you think it'll resolve YES." It means the market prices a 65% chance. If your honest estimate sits at 70%, that 5% edge justifies a specific position size.
Use these two calculators before placing any position:
- Implied Probability Calculator — convert any contract price to break-even win rate
- Kelly Criterion Calculator — find the optimal stake given your edge and bankroll