Prediction Arbitrage Calculator | Polymarket vs Kalshi

Updated: October 3, 2026 · Author: Jennie Chu · Reviewed by: Gemral Research Desk · Editorial Policy

How do you calculate prediction market arbitrage and Dutch book spreads across Polymarket and Kalshi?

Direct Answer: A prediction market arbitrage calculator polymarket kalshi computes mathematical price discrepancies across binary event platforms like Polymarket and Kalshi. When the combined implied probability of all mutually exclusive outcomes totals under 100% minus transaction fees, a Dutch book risk-free spread exists, locking in guaranteed yields regardless of real-world settlement outcomes.

Direct Answer: What is an implied probability to odds converter and event contract risk calculator?

An implied probability to odds converter translates raw market prices (such as 58 cents on a binary contract) into implied probabilities (58.0%), American odds (-138), and decimal multipliers (1.724). When combined with advanced sizing models, quantitative traders determine the exact delta-neutral capital allocation required to monetize cross-exchange pricing dislocations while hedging directional volatility and legislative settlement risks.

How does the implied probability to odds converter live transform prediction pricing across formats?

Modern prediction exchanges represent contract prices in disparate formats depending on whether they operate under decentralized protocols or CFTC-regulated Designated Contract Market (DCM) frameworks. The quantitative conversion engine standardizes these disparate expressions into a unified quantitative framework, enabling seamless comparative analysis:

• Binary Contract Cents (0¢ to 100¢): Platforms like Polymarket and Kalshi quote contracts directly in cents. A price of 64¢ represents an implied probability of 64.0%. At settlement, winning contracts redeem at exactly 100¢ ($1.00), while losing contracts expire worthless at 0¢ ($0.00).
• Implied Probability ($P$): Defined mathematically as $P = \\frac{\\text{Contract Price in Cents}}{100}$. For a contract trading at 64¢, $P = 0.64$.
• Decimal Multipliers ($M$): Widely utilized across European exchanges and quantitative betting terminals. Calculated as $M = \\frac{1}{P} = \\frac{1}{0.64} \\approx 1.5625$. A $1,000 position yields $1,562.50 upon successful settlement.
• American Moneyline Odds ($A$): Preferred by traditional U.S. sportsbooks. If $P > 0.50$, American odds are negative: $A = -\\frac{P}{1 - P} \\times 100 = -\\frac{0.64}{0.36} \\times 100 \\approx -178$. If $P < 0.50$, American odds are positive: $A = \\frac{1 - P}{P} \\times 100$. For a contract at 36¢, $A = +178$.
• Fractional Odds ($F$): Expressed as a ratio of profit to stake: $F = \\frac{1 - P}{P} = \\frac{0.36}{0.64} = \\frac{9}{16}$.

Our interactive cross-platform event spread calculator automatically performs continuous, real-time format harmonization, ensuring that quantitative analysts never make sizing errors caused by disparate quote conventions.

What is the mathematical foundation of a dutch book prediction market calculator?

The term "Dutch book" originates in probability theory and actuarial mathematics, describing a collection of bets on mutually exclusive events constructed such that the bettor secures a guaranteed profit regardless of which event actually transpires. In the context of modern event contracts, our dutch book betting calculator political prediction markets applies rigorous mathematical algorithms to structure risk-free portfolios across multiple exchanges.

Consider a binary event with exactly two possible states: $E$ (True) and $\\neg E$ (False). Suppose Exchange 1 (e.g., Polymarket) quotes Outcome $E$ at price $P_1(E) = 0.56$, while Exchange 2 (e.g., Kalshi) quotes Outcome $\\neg E$ at price $P_2(\\neg E) = 0.40$.

The sum of the purchase prices is:

$$\\sum P = P_1(E) + P_2(\\neg E) = 0.56 + 0.40 = 0.96$$

Because each winning contract pays out exactly $1.00 at settlement, purchasing one contract of $E$ on Exchange 1 and one contract of $\\neg E$ on Exchange 2 guarantees an exact payout of $1.00 for a total investment of $0.96. The gross profit is $1.00 - 0.96 = $0.04 per pair of contracts, yielding an immediate gross return of:

$$\\text{ROI}_{\\text{gross}} = \\frac{1.00 - 0.96}{0.96} = \\frac{0.04}{0.96} \\approx +4.167\\%$$

To scale this position across an institutional bankroll of $C$ dollars, the arbitrage algorithm calculates the optimal capital weighting to guarantee equal dollar payouts across both settlement branches:

$$W_1 = \\frac{P_2(\\neg E)}{P_1(E) + P_2(\\neg E)} = \\frac{0.40}{0.96} \\approx 41.67\\%$$

$$W_2 = \\frac{P_1(E)}{P_1(E) + P_2(\\neg E)} = \\frac{0.56}{0.96} \\approx 58.33\\%$$

For an institutional allocation of $100,000, the algorithm dictates allocating $41,667 to buy 74,405 contracts of $E$ at 56¢ on Exchange 1, and $58,333 to buy 145,833 contracts of $\\neg E$ at 40¢ on Exchange 2. Regardless of whether $E$ settles True or False, the gross payout equals $104,167, securing an identical dollar profit across all scenarios.

Why do pricing spreads emerge on our polymarket kalshi spread screener?

In frictionless markets with perfect information and instantaneous capital mobility, the law of one price guarantees that identical contracts trade at identical prices across all venues. However, cross-platform monitors frequently surface persistent pricing divergences ranging from 2.5% to 8.0%. These dislocations are driven by four structural market frictions:

1. Regulatory Architecture & User Base Segmentation: Polymarket operates as a decentralized prediction exchange settled in stablecoins (USDC) on the Polygon blockchain, attracting a global demographic of crypto-native traders, international macro participants, and algorithmic bots. In contrast, Kalshi is a designated contract market (DCM) regulated directly by the U.S. Commodity Futures Trading Commission (CFTC), restricted to verified U.S. residents transacting in fiat USD via ACH or wire transfers. Because capital cannot flow instantaneously between U.S. bank accounts and Polygon blockchain smart contracts, retail sentiment and regional news flow cause localized price dislocations that persist for hours or days.
2. Capital Inefficiency & Collateral Lockup: Event contracts require 100% full collateralization without fractional reserve leverage. When a trader buys a contract for 60¢, the exchange locks the full capital until settlement. Arbitrageurs cannot borrow event contracts to short-sell them in the traditional equity sense; they must deploy new physical cash on the opposing leg. When macro events have multi-month settlement horizons (such as November general elections or annual GDP targets), the opportunity cost of locked capital prevents small spread discrepancies from being instantaneously closed by institutional market makers.
3. Central Limit Order Book (CLOB) Liquidity Depth: While headline midpoint quotes may indicate an attractive spread, real-world execution requires crossing the bid-ask spread on both exchanges. A contract quoted at 55¢ bid / 58¢ ask on Polymarket versus 38¢ bid / 41¢ ask on Kalshi requires executing at the ask prices (58¢ + 41¢ = 99¢), reducing the actionable spread margin. Our screener computes depth-weighted effective spreads across full order book tiers to eliminate optical illusions.
4. Resolution Criteria Semantic Asymmetry: Even when contracts appear identical on the surface, their underlying legal rulebooks and resolution data sources may differ. For example, a contract on Federal Reserve interest rates might specify the effective federal funds rate (EFFR) on Kalshi while referencing the target range upper bound on Polymarket. Disparities in emergency meeting clauses or statistical revisions introduce basis risk that market makers price as a risk premium.

How does the event contract risk reward calculator quantify execution friction and fees?

An institutional trader never evaluates arbitrage opportunities purely on gross spread. Our net yield modeling engine incorporates comprehensive friction adjustments to compute true risk-adjusted net yields:

• Exchange Taker Fees: Polymarket historically levied 0% trading fees on political markets while testing fee structures on specific liquidity pools, whereas Kalshi charges variable regulatory exchange fees typically ranging from 0.1¢ to 0.7¢ per contract depending on volume tiers. A seemingly attractive 3% gross spread can be degraded by up to 1.2% in round-trip exchange fees.
• On-Ramp, Off-Ramp, and Gas Frictions: Arbitrageurs transferring capital between fiat banking systems and decentralized Polygon wallets incur ACH processing delays, wire transfer charges, crypto on-ramp fees, and Layer-2 blockchain gas fees. For smaller bankrolls under $10,000, fixed transfer overhead can eliminate prospective trading alpha.
• Annualized Percentage Yield (APY) vs. Absolute Spread: A 4% absolute spread on an event resolving in 3 days represents an extraordinary annualized return exceeding 480% APY ($4\\% \\times \\frac{365}{3}$). Conversely, the exact same 4% absolute spread on an event resolving in 9 months yields an annualized return of only 5.33% APY, which underperforms standard risk-free Treasury bills and high-yield money market funds. The platform dynamically computes annualized yields based on exact target resolution dates.
• Counterparty and Smart Contract Risk: Holding positions across decentralized protocols entails smart contract execution risk, oracle verification delays (such as UMA optimistic oracle challenges), and platform solvency considerations. Regulated DCM platforms feature clearinghouse protections under CFTC oversight but may impose position limits or emergency trading halts.

Step-by-Step Guide: How to execute delta-neutral prediction market arbitrage

Quantitative practitioners follow a systematic five-stage workflow when executing event contract arbitrage identified by our cross-platform event spread calculator:

1. Screen for Dislocated Pairs: Use the screening dashboard to filter active contracts where the sum of best ask prices across opposing outcomes totals less than 97¢, leaving a minimum 3.0% gross margin.
2. Verify Legal Resolution Rule Alignment: Cross-reference the exact contract resolution definitions in the Kalshi rulebook and Polymarket description. Confirm that both exchanges utilize identical official data feeds (such as the Bureau of Labor Statistics for CPI or the Federal Reserve Board of Governors for FOMC) and identical resolution deadlines.
3. Input Parameters into the Calculator: Enter the live ask prices ($P_A$ and $P_B$), exchange fee rates, and intended total bankroll into the calculator interface. The tool will immediately output the optimal capital sizing for each leg.
4. Execute Simultaneously via Limit Orders: To minimize execution leg risk (the risk of getting filled on one exchange while the price moves on the other), execute both orders simultaneously using automated API endpoints or pre-funded limit orders at the calculated target prices.
5. Monitor Settlement and Withdraw Capital: Track contract progress through the Demand Foresight Hub and Prediction Market Arbitrage Spoke. Upon market resolution, redeem winning contracts for $1.00 each, collect the guaranteed arbitrage profit, and reallocate capital into new emerging spreads.

Explore Institutional Alternative Data Terminals & VIP Pattern Scanners

Prediction market arbitrage represents just one facet of quantitative event-driven intelligence. Advanced traders combine event odds with institutional order flow, corporate insider accumulation, and automated chart pattern recognition:

• Institutional B2B Terminal Plans: Access institutional API feeds, automated WebMCP agentic actions, and low-latency CLOB order book telemetry through our Institutional B2B Plans.
• Crypto Pattern Scanner VIP: Connect prediction market macro probabilities directly to technical chart patterns, Wyckoff accumulation ranges, and liquidation squeeze triggers via the Crypto Pattern Scanner VIP.
• US Election Betting Odds & Stock Impact: Track sector-by-sector equity correlations and policy winners through our US Election Betting Odds & Stock Impact Tracker.
• Deep Flow & Government Contracts: Find early procurement and disclosure signals on the DEEP FLOW terminal and Government Contracts Radar.

How does an election contract arbitrage bot exploit pricing matrix inefficiencies?

Frequently Asked Questions

Review the comprehensive FAQ below for detailed guidance on market mechanics, tax treatments, API access, and mathematical Dutch book calculations.