Polymarket vs Kalshi vs Metaculus: Head-to-Head Comparison for Investors
Polymarket ($56B notional) vs Kalshi ($44B, CFTC-regulated) vs Metaculus (calibration-based). Nine-dimension comparison covering volume, regulation, fees, accuracy, and API access. Decision framework for which platform serves which investor need. Platform evolution scenarios through 2028.
Polymarket's notional volume stands at $56B. Kalshi has $44B and a CFTC licence. Metaculus has no money at stake but the best long-range calibration. Three platforms, three very different architectures. This comparison maps when to use which, the tradeoffs that matter for investors, and where each platform's data is most reliable.
Head-to-head comparison
Platform comparison: March 2026
| Feature | Polymarket | Kalshi | Metaculus |
|---|---|---|---|
| Total volume | $56B notional | $44B notional | N/A (no money) |
| Regulation | CFTC (pending US launch) | CFTC-regulated DCM | N/A |
| Currency | USDC (crypto) | USD (bank transfer) | Reputation points |
| Fees | ~2% on winnings | 2-4% | Free |
| US access | Waitlist (invite-only) | Full access | Full access |
| API | Public (no auth) | Free account required | Public |
| Best for | Politics, crypto, macro | Economics, weather, Fed | Science, tech, long-range |
| Market creation | Anyone can create | CFTC-approved only | Community moderated |
| Key weakness | Whale manipulation risk | Lower non-US liquidity | No financial incentive |
Source: Platform data, Bloomberg, CoinGape, Techopedia. As of March 2026.
Decision framework: when to use which platform
| Investment question | Primary source | Cross-reference | Signal quality |
|---|---|---|---|
| Will the Fed cut in June? | Kalshi | CME FedWatch, Polymarket | Very high |
| US election outcome? | Polymarket | Kalshi, PredictIt | Very high |
| EU AI regulation timeline? | Metaculus | Polymarket (if market exists) | High |
| Will CPI come in above 3%? | Kalshi | Cleveland Fed Nowcast | Very high |
| Geopolitical risk (12+ months)? | Metaculus | Good Judgment (if available) | Medium-high |
| Crypto price targets? | Polymarket | Kalshi, Deribit options | Medium |
Platform evolution scenarios: 2026-2028
If: Polymarket launches regulated US version; Coinbase enters prediction markets
Then: Market volume doubles; institutional adoption accelerates; prediction market data becomes a standard Bloomberg-style input; Futuratty-type translation services scale
If: Kalshi dominance in regulated space; Polymarket stays crypto-native
Then: Two-tier market: Kalshi for institutional/US, Polymarket for global/crypto; data aggregation becomes more valuable as platforms specialise
If: Regulatory crackdown limits growth of one or both platforms
Then: Reduced signal quality; reversion to traditional forecasting methods for some use cases; surviving platform gains monopoly premium
Data sources
- Polymarket - Platform data, API documentation, volume data, March 2026
- Kalshi - Platform data, CFTC filings, Robinhood integration data, March 2026
- Metaculus - Calibration data and community forecasting metrics, March 2026
- Bloomberg - Prediction markets feature article, 2026
- NPR - Prediction market trader analysis, January 2026
- NBER - Working paper on Kalshi accuracy, January 2026
- Futuratty platform analysis, March 2026
Frequently asked questions
Which is better: Polymarket or Kalshi?
It depends on your use case. Polymarket has higher total volume ($56B notional vs Kalshi's $44B as of February 2026), more creative market categories, and lower fees on most contracts. Kalshi is CFTC-regulated, uses USD, offers unique economic markets (CPI, GDP, weather) that require regulatory approval, and has integrated with Robinhood. For US-based investors who want regulatory protection, Kalshi is the safer choice. For global users seeking the deepest liquidity on political events, Polymarket leads.
Is Polymarket legal in the US?
Polymarket acquired CFTC-licensed exchange QCEX and has relaunched a US-approved version, but access remains on an invite-only waitlist as of February 2026. The original Polymarket was not available to US users due to regulatory restrictions. Kalshi has been fully CFTC-regulated since launch and is available to US residents. If you're a US-based investor, Kalshi is the compliant option with immediate access.
How accurate is Metaculus compared to prediction markets?
Metaculus uses reputation-based community forecasting rather than real-money markets. Its calibration data shows strong accuracy on scientific and technological questions - predictions at the 70% confidence level resolve correctly approximately 70% of the time. For political and near-term economic events, Polymarket and Kalshi show tighter accuracy due to deeper liquidity and financial incentives. Metaculus excels on long-range (1-5 year) questions where money markets tend to be thin.
What fees do Polymarket and Kalshi charge?
Polymarket charges a 2% fee on winnings for most markets (global), or a 0.1% taker fee for US users - making it free to buy and cheaper than Kalshi on contracts priced above roughly 29 cents. Kalshi charges 2-4% fees depending on the contract type. Both platforms are free to create accounts. For investors using prediction market data (not trading), both platforms provide free access to pricing data.
Can I use prediction market data without trading?
Yes, and for most investors this is the higher-value approach. Polymarket's API is publicly accessible without authentication. Kalshi requires a free account for API access. Metaculus data is fully public. You can monitor prediction market prices as probability signals for your investment decisions without ever placing a trade. This avoids platform risk, liquidity risk, and the opportunity cost of capital locked in contracts.
What is Good Judgment and how does it compare?
Good Judgment is an enterprise forecasting service based on Philip Tetlock's 'superforecaster' research. It uses vetted expert panels rather than open markets. Pricing starts at $50K+ annually for institutional clients. Its track record is strong, especially on geopolitical and long-range policy questions. The tradeoff: expensive, not public, and slower to update than real-time markets. Best for institutions needing curated intelligence on specific geopolitical scenarios.
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