Kalshi vs Polymarket
The two largest prediction market platforms run on completely different rails — one a CFTC-regulated US exchange, the other a blockchain-native protocol. Prices on identical markets routinely disagree by several percentage points. Here's what they have in common, where they differ, and where they're disagreeing right now.
brier currently tracks 1,188 markets traded on both Kalshi and Polymarket. The average price disagreement between the two venues right now is 3.2 pp. Kalshi is cheaper on 537 markets; Polymarket is cheaper on 616. Which to use depends entirely on the market — see live dislocations below.
Side-by-side: what's different
| Dimension | Kalshi | Polymarket |
|---|---|---|
| Regulatory status | CFTC-registered DCM (Designated Contract Market) | On-chain protocol; US access expanded via 2025 QCEX acquisition |
| Settlement currency | USD (bank-issued) | USDC on Polygon |
| Deposit methods | ACH, debit card, wire | USDC bridge from any wallet / on-ramp |
| Market types where it shines | Economic data, weather, US politics, sports | Crypto, world politics, entertainment, viral events |
| Custody | Custodied (your USD sits with Kalshi) | Self-custody (your USDC stays in your wallet) |
| Market creation | Curated by Kalshi | Open submissions, curated by Polymarket admins |
| Trading hours | 24/7 | 24/7 |
| API access | Public REST + websocket | Public REST (Gamma) + on-chain |
Where they're disagreeing the most right now
Pulled live from brier's mapping engine — the biggest current price gaps on markets tracked on both venues.
Which one should you use?
For any specific trade, the right answer is whichever has the better price. That's the entire premise behind brier: a 4 percentage point gap on a market resolving in a week is real money, and you don't have to guess which side has it — every paired market shows both prices side-by-side, and the cheaper venue is labeled directly.
That said, there are practical reasons to lean one way:
- Use Kalshi if you want USD deposits and withdrawals, prefer a custodied account, trade economic data or US elections, or want a CFTC-regulated venue with the legal clarity that comes with it.
- Use Polymarket if you already hold crypto, want self-custody, trade crypto-flavored or international markets, or prefer the wider catalog of long-tail markets.
- Use brier if you want to use both — the whole point of comparing is that no single venue wins on every market. The cheaper price often flips from week to week as flow lands on one side or the other.
What both platforms do well
It's worth noting how much the two have in common. Both run continuous 24/7 markets on objectively-resolvable questions. Both offer public APIs that brier (and others) use to pull live prices. Both denominate contracts in cents (a $1 binary contract), which makes comparing prices trivial — a 60¢ Kalshi YES and a 56¢ Polymarket YES are directly comparable as 60% vs 56% implied probability.
Both platforms are also significantly more sophisticated than traditional sportsbooks: payouts are based on order book depth, not house odds; you can sell positions before resolution; you can short (buy NO) on either side; and you can scale into a position rather than betting the whole stake up front.
Frequently asked questions
Is Kalshi better than Polymarket?
Neither is strictly better. Kalshi is a US-regulated exchange with USD deposits and a focus on economic, weather, and US-political markets. Polymarket is built on the Polygon blockchain, settles in USDC, and tends to have a wider catalog plus larger 24-hour volume on its top markets. For any specific question, the right venue is usually the one offering the better price — which is what brier shows you on every paired market.
Is Polymarket legal in the US?
Polymarket entered into a settlement with the CFTC in 2022 that restricted access for US users. Since then, the regulatory landscape has evolved — including Polymarket's acquisition of QCEX (a CFTC-registered exchange) — and US access has expanded. Check Polymarket's site for the current eligibility rules in your jurisdiction. Kalshi is a CFTC-regulated DCM and has been available to US users from the start.
Which one has lower fees?
Both are competitive. Kalshi charges trading fees that vary by market type (often quoted in the low single-digit cents per contract). Polymarket charges no per-trade fee but you pay Polygon network gas costs and a small spread captured by the AMM/CLOB design depending on the market. For high-frequency users the difference is real; for casual traders, both feel cheap. The bigger source of cost is usually the bid-ask spread, which brier displays directly so you can compare.
Do prices stay in sync across Kalshi and Polymarket?
No. The two venues have different user bases, different liquidity, and no arbitrage mechanism connecting them. Prices on identical markets often differ by 2–10 percentage points, sometimes more. That gap is exactly what brier is built to surface — see the live dislocations section below.
How do I deposit money?
Kalshi accepts USD via ACH bank transfer, debit card, and wire. Polymarket settles in USDC on Polygon — you fund it by sending USDC to your wallet (on-ramps are available through their site and via standard crypto exchanges). Brier is venue-agnostic and doesn't custody anything; you trade directly on each platform.
What types of markets does each platform cover?
Kalshi leans toward economic indicators (CPI, Fed decisions, jobs reports), weather, US politics, and an expanding sports lineup. Polymarket leans toward crypto, broader politics (including international elections), entertainment (Billboard, Netflix rankings), and high-volume world events. Both cover the major event categories; the differences are in depth and which side has more liquidity for any specific question.
275 markets tracked. Both venues, side-by-side, with live prices.