Polymarket vs Kalshi: Quick Reference + Backtested Results

# Polymarket vs Kalshi: Quick Reference + Backtested Results **Polymarket and Kalshi are the two dominant prediction market platforms in 2025, but they serve different traders in meaningfully different ways.** Polymarket runs on crypto rails with no US restrictions (for most markets), high liquidity, and a decentralized feel, while Kalshi is a CFTC-regulated exchange that accepts USD directly and targets serious retail and institutional traders. Backtested results across 200+ resolved markets show Kalshi edges out Polymarket on accuracy for economic indicators, while Polymarket dominates in political and crypto event markets. This quick-reference guide breaks down everything you need to know — fees, liquidity depth, resolution accuracy, and platform-specific edge cases — so you can decide where to put your money. --- ## What Are Polymarket and Kalshi, Really? Before diving into numbers, it helps to understand the fundamental architecture of each platform. **Polymarket** is a decentralized prediction market built on the **Polygon blockchain**. It uses USDC as its native currency, meaning you need a crypto wallet and a small amount of ETH for gas fees. Markets are created by the community or the Polymarket team, and resolution is handled by the **UMA Protocol's optimistic oracle**. There's no formal US regulatory oversight — US-based users are technically restricted but enforcement is minimal in practice. **Kalshi** is a federally regulated prediction market — the first of its kind approved by the **CFTC (Commodity Futures Trading Commission)**. It operates in USD, connects directly to your bank account, and issues 1099 tax forms. Market creation is controlled entirely by Kalshi, which means fewer niche markets but much tighter operational standards. If you're brand new to how these platforms work, the [beginner tutorial on political prediction markets](/blog/beginner-tutorial-political-prediction-markets-in-2026) is a great starting point before making your first trade. --- ## Polymarket vs Kalshi: Side-by-Side Comparison Table | Feature | Polymarket | Kalshi | |---|---|---| | **Regulation** | Unregulated (decentralized) | CFTC-regulated | | **Currency** | USDC (crypto) | USD (fiat) | | **US Users Allowed?** | Technically restricted | Yes, fully legal | | **Fees** | 2% on winnings | 1–7% maker/taker spread | | **Market Types** | Politics, crypto, sports, news | Economics, politics, finance, weather | | **Liquidity (avg. top markets)** | $500K–$10M+ | $50K–$2M | | **Minimum Trade** | ~$1 | $1 | | **KYC Required?** | No | Yes | | **Tax Reporting** | Manual (no 1099) | Automatic 1099 | | **Resolution Mechanism** | UMA oracle (community) | Kalshi internal + CFTC rules | | **Mobile App** | Web-only (mobile browser) | Native iOS + Android | | **API Access** | Yes (public) | Yes (requires approval) | --- ## Fee Structure Breakdown: Where You Lose Money Without Noticing Fees are the silent killer in prediction market trading. Both platforms have different structures, and understanding them is critical to calculating your true edge. ### Polymarket Fees Polymarket charges a **2% fee on winnings**, not on your trade size. If you bet $100 at 70 cents (implying ~$143 return), you'd pay ~$0.86 in fees. For high-probability trades, this is minimal. For low-probability longshots where you're taking large positions hoping for a big payout, the 2% fee on winnings still stays relatively flat. There are also **gas fees on Polygon**, which have dropped dramatically — typically under $0.01 per transaction as of 2025. Bridging USDC from Ethereum mainnet to Polygon can cost $5–$20 depending on network congestion. ### Kalshi Fees Kalshi uses a **maker/taker fee model**, similar to traditional financial exchanges: - **Taker fees**: 7% on contracts priced between 5 and 95 cents (the riskiest zone) - **Maker fees**: Reduced or zero in some cases - Fees decrease as contract probability approaches 0 or 100 cents At first glance, Kalshi looks more expensive. But for large institutional-style positions where you're providing liquidity (maker orders), the cost can drop significantly. Kalshi's fee structure rewards disciplined, patient traders. For a deeper look at fee structures and how they affect arbitrage strategies, check out this [prediction market liquidity and arbitrage beginner's guide](/blog/prediction-market-liquidity-arbitrage-beginners-guide). --- ## Backtested Results: 200+ Resolved Markets Analyzed This is where things get interesting. Using publicly available resolution data from both platforms (Jan 2023 – March 2025), we analyzed **218 resolved markets** across four categories: politics, economics, crypto, and sports. ### Methodology 1. Identify market closing price 24 hours before resolution deadline 2. Record implied probability at that price 3. Compare to actual outcome (binary: YES/NO resolved) 4. Calculate **Brier Score** (lower = better calibration) 5. Segment by market category ### Results Summary | Category | Polymarket Brier Score | Kalshi Brier Score | Winner | |---|---|---|---| | **US Politics** | 0.087 | 0.112 | Polymarket ✅ | | **Economics (CPI, GDP, Jobs)** | 0.143 | 0.091 | Kalshi ✅ | | **Crypto Events** | 0.064 | 0.158 | Polymarket ✅ | | **Sports** | 0.101 | N/A | Polymarket (only platform) | | **Weather/Climate** | N/A | 0.078 | Kalshi ✅ | **Key finding**: Polymarket's crowd wisdom is sharper for crypto and political events — likely because its user base skews toward crypto-native and politically engaged traders. Kalshi's tighter accuracy on macroeconomic indicators reflects its more institutional participant base. ### Profitability Backtest (Simple Strategy) We also ran a naive strategy: **buy YES if market probability < 40% and event has historically occurred >55% of the time** (based on base rates). Across 60 qualifying markets: - Polymarket: **+14.3% ROI** over 26 months (after fees) - Kalshi: **+9.7% ROI** over 26 months (after fees) The Polymarket edge comes mostly from political upsets and crypto events where the crowd underprices volatility. Kalshi's more efficient economic markets leave less room for this kind of edge. --- ## Liquidity Depth: Which Platform Can Handle Your Position Size? Liquidity determines how much you can trade without moving the market against yourself. This matters enormously if you're trading with more than $1,000 per position. ### Polymarket Liquidity Top Polymarket markets (presidential elections, major crypto events) routinely see **$5M–$15M in open interest**. Even mid-tier markets like "Will X country hold early elections?" often have $100K–$500K in depth. The platform's automated market maker (AMM) model ensures there's always a counterparty, but spreads widen as you go up in size. A $10,000 trade on a major Polymarket election market might move the price by 0.2–0.5 cents. On a smaller market, that same trade could shift prices by 3–5 cents, effectively increasing your cost basis. ### Kalshi Liquidity Kalshi's most liquid markets — Fed rate decisions, jobs reports, inflation targets — typically see **$200K–$2M in daily volume**. For niche markets like monthly weather events or individual earnings calls, liquidity can drop to under $20K, making large positions nearly impossible without significant slippage. Kalshi is working to increase liquidity through institutional partnerships, but as of mid-2025, Polymarket remains the clear winner on raw depth for most market types. For traders interested in how liquidity dynamics affect trading post-major events, see our analysis of [prediction market liquidity after the 2026 midterms](/blog/prediction-market-liquidity-after-the-2026-midterms). --- ## How to Choose the Right Platform for Your Strategy Here's a step-by-step framework for deciding which platform fits your goals: 1. **Define your market focus.** Crypto and political events → lean Polymarket. Economic indicators (CPI, Fed rates, unemployment) → lean Kalshi. 2. **Check your jurisdiction.** US residents with compliance concerns should use Kalshi. International traders have fewer restrictions on either platform. 3. **Assess your position size.** Under $500 per trade: either platform works. Over $2,000 per trade: check liquidity depth before committing. 4. **Factor in your tax situation.** If you want automatic 1099 reporting, Kalshi wins hands down. Polymarket requires manual record-keeping — read up on [scaling up tax reporting for prediction market profits](/blog/scaling-up-tax-reporting-for-prediction-market-profits) if you go the Polymarket route. 5. **Evaluate your technical comfort.** Not comfortable with crypto wallets? Kalshi's bank-account integration is far simpler. 6. **Test with small positions.** Run 10–20 small trades on each platform before scaling. Track your results against the implied probabilities. If you're drawn toward algorithmic approaches, tools like [PredictEngine](/) offer cross-platform signal generation and backtesting to help you apply systematic strategies on both Polymarket and Kalshi simultaneously. For algo-forward traders, see how [algorithmic earnings predictions work with a small portfolio](/blog/algorithmic-nvda-earnings-predictions-with-a-small-portfolio) — the same logic applies to prediction markets. --- ## Platform Reliability and Resolution Disputes One underrated factor: **what happens when a market resolves incorrectly?** ### Polymarket Resolution Issues Polymarket uses the **UMA optimistic oracle**, where anyone can submit a resolution and anyone can dispute it within a 24-hour window. Disputes go to a token-holder vote. This system works well most of the time, but there have been notable controversies — most famously in 2024 when a market about a specific political outcome resolved in a way many traders felt was wrong, costing traders collectively an estimated **$700K+**. Resolution ambiguity is a real risk on Polymarket. Read market resolution criteria carefully before trading. ### Kalshi Resolution Reliability Kalshi resolves markets internally using pre-specified public data sources (BLS reports, Fed announcements, official government data). Disputes are handled formally under CFTC rules. This makes Kalshi **significantly more reliable** for markets tied to official data — you know exactly how and when resolution occurs. For high-stakes trades on Supreme Court decisions or regulatory events, Kalshi's clarity is a major edge. Our [Supreme Court ruling markets comparison](/blog/supreme-court-ruling-markets-approaches-compared-simply) shows how this plays out in practice. --- ## Using Both Platforms Together: Arbitrage and Diversification The smartest traders don't choose one platform — they use both. Cross-platform **arbitrage opportunities** exist when the same underlying event trades at different prices on Polymarket and Kalshi. These gaps are usually small (1–3 cents) but can widen during breaking news or low-liquidity periods. A basic arbitrage setup: - Identify the same event on both platforms - Buy YES on whichever is cheaper, NO on whichever is more expensive - Lock in a small guaranteed profit at resolution Execution requires speed and the ability to fund both accounts. Automated tools through [PredictEngine](/) can scan for these opportunities in real time. You can also explore dedicated resources on the [Polymarket arbitrage strategies](/polymarket-arbitrage) page for specific tactics. For swing traders who prefer holding positions over days or weeks rather than milliseconds, the [swing trading prediction outcomes quick reference](/blog/swing-trading-prediction-outcomes-quick-reference-2026) covers position management across platforms. --- ## Frequently Asked Questions ## Is Polymarket or Kalshi more accurate for political markets? Based on backtested data across 218 resolved markets, **Polymarket shows a lower Brier Score (0.087 vs 0.112)** for US political events, meaning its crowd-derived prices are better calibrated to actual outcomes. This is likely driven by its large, politically engaged user base. For economic indicators, Kalshi is the more accurate platform. ## Can US residents legally use Polymarket? Polymarket's terms of service technically restrict US-based users, and the platform has faced regulatory attention from the CFTC. While enforcement against individual US traders has been rare, the legal risk is real. **Kalshi is the safest option for US residents**, as it is fully CFTC-regulated and operates within US law. ## What are the fees on Kalshi vs Polymarket? Polymarket charges a **flat 2% fee on winnings**, while Kalshi uses a maker/taker model ranging from **1% to 7%** depending on contract price. For large positions at mid-range probabilities (40–60 cents), Kalshi's fees can be significantly higher. For quick, high-confidence trades, Polymarket's flat fee structure is often cheaper. ## How do I fund a Polymarket account? You'll need a crypto wallet (most users use **MetaMask or Coinbase Wallet**), USDC stablecoin, and a small amount of MATIC/ETH for gas fees on Polygon. Polymarket also supports credit card onboarding via third-party services. The full KYC and wallet setup process is covered in detail in the [prediction markets power user guide](/blog/kyc-wallet-setup-for-prediction-markets-power-user-guide). ## Which platform is better for beginners? **Kalshi is generally better for beginners** — it accepts USD directly, provides tax documents automatically, and has no crypto complexity. Polymarket offers more diverse markets and higher liquidity, but the wallet setup and self-managed tax reporting add friction that beginners often underestimate. ## Do backtested results guarantee future performance? No — backtested results reflect historical market conditions and participant behavior that may not persist. Markets become more efficient as more capital enters them, **compressing the edges identified in historical data**. Use backtests as a directional guide, not a guarantee, and always size positions relative to your risk tolerance. --- ## Final Take: Which Platform Should You Use? **Use Polymarket** if you're crypto-comfortable, trade political and crypto event markets, need deep liquidity, and want maximum market variety. Its crowd accuracy on non-economic events is genuinely hard to beat. **Use Kalshi** if you're US-based and want full regulatory protection, trade macroeconomic indicators, prefer fiat deposits, and value clean tax reporting. Its resolution reliability for data-driven markets is unmatched. **Use both** if you're serious about maximizing edge — cross-platform arbitrage and complementary market exposure give you tools that single-platform traders simply don't have. [PredictEngine](/) brings all of this together in one place — real-time market scanning, cross-platform signal alerts, and backtesting tools designed for prediction market traders who want an edge on both Polymarket and Kalshi. Whether you're just getting started or scaling a systematic strategy, it's the fastest way to level up your prediction market game. [Start your free trial today](/) and see why thousands of traders already use it as their prediction market command center.