Polymarket vs Kalshi Arbitrage in 2026: How to Find Opportunities, Calculate Profit and Execute

Prediction market arbitrage is one of the few edges that doesn't require you to be right about the outcome. If Kalshi shows 65¢ YES on a market and Polymarket shows 42¢ NO on the same event, you can take both sides simultaneously and lock in a profit regardless of how the market resolves as long as the spread exceeds your combined fees.

That's the entire logic. But most guides stop there and call it done. This one doesn't!

What actually separates traders who capture these opportunities from those who don't is knowing the precise minimum spread required to profit after both platforms' specific fee structures, recognising which market categories surface opportunities most reliably, and executing both sides before the window closes. This guide covers all three with real numbers, and worked examples. If you're still deciding between platforms, start with the full Kalshi vs Polymarket comparison before going further.

Why Prediction Market Arbitrage Is Different From Crypto Arbitrage

If you've executed arbitrage on crypto exchanges, prediction market arb will feel familiar in concept and meaningfully different in practice. Three distinctions matter.

Binary resolution changes the math entirely.

In crypto arb, you're exploiting a price difference for the same asset on two exchanges. In prediction markets, you're buying YES on one platform and NO on another. For the trade to be profitable, the combined cost of both positions must be less than $1.00 because only one side will ever pay out $1.00.

A YES at 58¢ and a NO at 47¢ costs $1.05 combined. That's a loss before fees even enter the picture.

Capital is locked until resolution.

Crypto arb closes in seconds. Prediction market arb ties up your capital until the market resolves which could be two weeks or four months. A $200 profit on $2,000 deployed sounds reasonable until you realise the market resolves in 90 days and you've earned a 4% return on annualised capital.

Liquidity is thinner and execution risk is real.

On liquid crypto exchanges, arb closes in milliseconds. On prediction markets, placing one side of a trade doesn't guarantee you can fill the other before the spread corrects. Thin order books mean partial fills are common.

The Mechanics: How Cross-Platform Prediction Market Arbitrage Works

The Basic Setup

The structure is straightforward: the same event is listed on both Kalshi and Polymarket, but each platform's users have priced it differently. You buy the outcome that's underpriced on one platform and the opposite outcome on the other. If both positions together cost less than $1.00, a gross arbitrage opportunity exists.

Here's a non-profitable example first, because understanding why a spread doesn't work is just as important as knowing when it does.

Example: Fed rate cut, March 2026 meeting

• Kalshi: YES at 58¢
• Polymarket: NO at 47¢
• Combined cost: $1.05

Regardless of whether the Fed cuts rates, one of your positions pays $1.00. You've spent $1.05 to guarantee a $1.00 return. That's a gross loss of $0.05 per contract; and fees haven't been counted yet. No arb exists here.

Now the same event, repriced:

• Kalshi: YES at 38¢
• Polymarket: NO at 57¢
• Combined cost: $0.95

You've spent $0.95 to guarantee a $1.00 return. That's a gross spread of $0.05 per contract and now the question is whether that spread survives fees.

The Math That Determines Profitability

Every arbitrage calculation follows three steps.

Step 1 Gross spread

Add the YES price on one platform to the NO price on the other. If the sum is less than $1.00, a gross opportunity exists. If it equals or exceeds $1.00, stop there is no opportunity regardless of fees.

Gross Spread = $1.00 − (YES price + NO price)

If gross spread ≤ 0: no arb. Walk away.

Step 2 Fee calculation

Subtract the fees charged by each platform on your specific trade. This is where fee structures matter enormously. See the exact fee structures on both platforms for current numbers.

Step 3 Net profit

Net Profit = ($1.00 − YES price − NO price) − (Polymarket fees + Kalshi fees)

If net profit > 0: the trade is viable. If net profit ≤ 0: fees consume the spread.

The Minimum Spread You Need to Break Even

Using current 2026 fee structures:

Polymarket (Global):Most markets carry zero trading fees. For fee-enabled markets (primarily 15-minute crypto contracts), fees follow a dynamic curve peaking at ~50% probability. For standard markets used in cross-platform arb: effectively $0 in trading fees.

Polymarket (US, via FCM intermediaries):Flat taker fee of 0.10% on the total contract value. A $1,000 position costs $1.00 in fees.

Kalshi:Dynamic formula-based fee for takers: ceil(0.07 × P × (1 − P) × 100) / 100 per contract, where P is the contract price between 0 and 1. This peaks at 50% probability (P = 0.50) and falls toward zero at extremes.

At P = 0.50:Kalshi taker fee = ceil(0.07 × 0.50 × 0.50 × 100) / 100 = $0.0175 per contract

Minimum Spread Calculation (Kalshi taker + Polymarket Global, standard market)

For a market where YES is at 50¢ on Kalshi and NO is somewhere on Polymarket:

• Kalshi fee at 50¢: ~$0.0175 per contract
• Polymarket Global fee: $0.00 (standard market)
• Minimum gross spread required: $0.0175 per contract approximately 1.75 cents

For Polymarket US (0.10% taker):

• On 57¢ NO: fee = 0.10% × $0.57 = $0.00057 per contract
• Combined minimum: approximately $0.018–$0.02 per contract depending on prices

Practical rule of thumb:Any combined YES+NO price below $0.98 on a standard Kalshi market is worth calculating further. Any spread of less than 2 cents after fees is marginal and likely not worth execution risk.

A Fully Worked Example Step by Step

Market: "Will the S&P 500 close above 6,000 on March 31, 2026?"

First check: is there a gross opportunity?

• Kalshi: YES at 44¢
• Polymarket: NO at 61¢
• Combined: $1.05 → No gross arb. Move on.

Second scenario: same event, different pricing

• Kalshi: YES at 38¢
• Polymarket Global: NO at 57¢
• Combined: $0.95 — gross spread of $0.05

Fee calculation on 100 contracts:

Kalshi taker fee at P = 0.38: 0.07 × 0.38 × (1 − 0.38) = 0.07 × 0.38 × 0.62 = 0.016492 Rounded up: $0.017 per contract × 100 = $1.70 totalPolymarket Global (standard market): $0.00

Net profit calculation:

• Gross profit: 100 × $0.05 = $5.00
• Kalshi fees: $1.70
• Polymarket fees: $0.00
• Net profit: $3.30 on 100 contracts

Capital deployed: 100 × $0.38 (Kalshi) + 100 × $0.57 (Polymarket) = $38 + $57 = $95.00

Return: 3.47% on capital deployed

Is it worth executing? The market resolves in 60 days. Annualised return: 3.47% × (365/60) = ~21.1% annualised. That's a meaningful return but only if you can fill both sides before the spread closes, and only if the market resolves cleanly without dispute.

At $95 deployed, the absolute profit is $3.30. To make prediction markets a meaningful income source, you'd need to either scale position size significantly or run many concurrent opportunities.

The Three Types of Prediction Market Arbitrage

Type 1 Cross-Platform Binary Arbitrage

The strategy this guide primarily covers. Same event, different platforms, opposite sides. Lowest risk when both legs fill simultaneously. Main execution risk: one side fills, the other doesn't before the spread corrects leaving you holding a directional position you didn't intend to take.

Type 2 Related Market Arbitrage

Same platform, logically linked markets that are mispriced relative to each other.

Example: "Will Candidate A win the presidential election?" trades at 55¢ on Polymarket while "Will Candidate A or Candidate B win the election?" trades at 80¢ when those are the only two viable candidates. This is internally inconsistent pricing.

No cross-platform execution risk. Requires sharper logical analysis to identify but eliminates the speed problem of Type 1.

Look for:Mutually exclusive and exhaustive markets on the same platform"At least one of" markets vs individual outcome marketsSum-of-parts mispricing where individual candidate or outcome markets don't add up correctly to 100¢

Type 3 Resolution Timing Arbitrage

A market is clearly heading toward YES or NO resolution based on publicly available information, but the market price hasn't updated yet. This sits at the edge of pure arbitrage; it's really an information advantage rather than structural mispricing.

This type generates some of the highest single-trade returns on prediction markets. For deeper coverage, see our directional trading strategies on Polymarket. This guide focuses on Types 1 and 2.

How to Find Live Arbitrage Opportunities

Manual Method What to Look For

Open the same high-volume event on both platforms simultaneously. Focus on markets with resolution dates 2–8 weeks out short enough that capital tie-up is manageable, long enough that the market is still actively traded. Prioritise markets where one platform has notably lower liquidity; thin order books are more prone to mispricing.

The best timing for manual checks: immediately after major news events (Fed announcements, election results, economic data releases) when prices haven't fully updated on both platforms simultaneously. A spread that exists at 2pm on a news day may be gone by 2:05pm but that 5-minute window is real.

Checklist for manual arb scanning:

• Same underlying event listed on both platforms (verify wording  resolution criteria sometimes differ)
• Sum of YES + NO prices below $0.98
• Sufficient liquidity on both sides to fill your target position size
• Resolution date within 8 weeks
• No open resolution disputes or ambiguous language in the market rules
• Confirm you can legally access both platforms from your location. Check if Polymarket is available in your country before funding your account 

The Best Market Categories for Arb Opportunities

Not all market categories are equally fertile.

Economic data markets (Fed meetings, CPI, NFP releases) consistently produce cross-platform discrepancies. Kalshi's more traditional finance user base and Polymarket's crypto-native users often price macro events differently particularly in the 48-hour window before and after data releases.

Political markets around announcement windows not election night, but policy announcement dates, legislative vote dates, and regulatory decision deadlines create temporary dislocations as news hits one platform's users faster than the other's.

Crypto price markets are the most volatile for arb. Polymarket's crypto users react faster to blockchain-adjacent news; Kalshi's users may lag. However, 15-minute crypto markets on Polymarket carry fee surcharges that reduce net profitability factor before trading these categories.

Using Analytics Tools to Monitor Systematically

Manual scanning works for occasional traders. For anyone running arb at scale, you need a system that monitors both order books simultaneously and flags when combined YES+NO prices drop below your minimum threshold.The core logic is simple: pull real-time prices from both platforms via API, compute YES + NO for every matched market, and surface any pair where the sum falls below $0.98. 

Tools like Laika AI's prediction market analytics can help surface these discrepancies automatically, reducing the time between opportunity and execution from minutes to seconds.

Track Prediction Market Opportunities Systematically

Manually checking two platforms every hour isn't a strategy, it's a job. Use Laika AI's analytics tools to monitor Polymarket and Kalshi simultaneously and get alerted when arbitrage conditions appear. Try Laika AI Free →

Execution The Practical Realities

Speed and Execution Risk

Arb windows in prediction markets close faster than most first-time arb traders expect. Another trader or a market maker correcting the mispricing can wipe out a spread in under a minute.

Practical steps to improve execution speed:

• Have both platforms open in adjacent browser tabs, logged in with funds pre-loaded on both sides
• Decide your position size before you start scanning don't do the math while the spread is open
• Use market orders on the platform with higher liquidity to guarantee fill; consider limit orders on the thinner side if the spread gives you room
• For Polymarket Global: USDC must be pre-funded on-chain. Deposit lag kills arb opportunities

Partial fills are the most common failure mode. If Kalshi fills 60 of your 100 contracts but Polymarket runs dry at 40, you're holding a net directional position on 20 contracts. Know your policy before this happens: either accept the directional exposure, immediately close the unfilled leg, or set a minimum fill threshold below which you won't execute.

Capital Requirements and Opportunity Cost

Arb isn't a small-capital strategy at meaningful profit levels.

Consider the math: a $0.03 net spread on a market resolving in 60 days generates 3% over two months approximately 18% annualised. That sounds attractive. On $500 deployed, that's $15. On $10,000 deployed, it's $300. The absolute dollar return only becomes meaningful at significant position sizes.

Minimum practical capital for prediction market arb: $2,000–$5,000 per opportunity, with funds split across both platforms. Factor in the opportunity cost against alternatives directional prediction market trades, yield on stablecoins, or other deployed capital.

What Happens When Arb Goes Wrong

Resolution dispute

A market's resolution is contested or delayed. You're holding both sides theoretically neutral but if the market is voided rather than resolved, both positions may be returned at cost rather than paying out $1.00. Your arb profit is wiped.

This is rare but happens most often on markets with ambiguous resolution criteria. Read the rules before trading.

Execution failure

You fill one side but can't fill the other before the spread closes. Now you hold a directional position in a market you never intended to take a view on.

The fix: always set a firm rule that if you can't fill both sides within a defined timeframe (30–60 seconds), you cancel or reverse the filled leg immediately.

Current Arbitrage Opportunity Types Updated February 2026

The following categories have been producing the most consistent cross-platform pricing discrepancies in recent weeks. These are market types, not specific live markets specific prices change hourly.

Spreads widen significantly in the 24–48 hours before scheduled resolution events and narrow quickly after. Check both platforms in the morning before the US market opens for the freshest pricing discrepancies.

If you are looking for alternatives to Polymarket, see our breakdown of other prediction market platforms worth considering, especially if you're evaluating where cross-platform arbitrage opportunities are most likely to emerge.

Frequently Asked Questions

Q1: What is Polymarket Kalshi arbitrage?

It's a market-neutral strategy where you buy YES on one platform and NO on the other for the same event. If the combined cost of both positions is less than $1.00 and the spread exceeds your combined fees, you lock in a guaranteed profit regardless of the outcome.

Q2: What minimum spread do I need to profit from Polymarket-Kalshi arbitrage in 2026?

With Kalshi's taker fees (formula-based, averaging ~1.2% of contract value) and Polymarket Global's zero fees on standard markets, you need a gross spread of approximately 1.75–2.5 cents per contract depending on the price point. Any combined YES+NO price below $0.98 is worth calculating explicitly.

Q3: Does Polymarket charge fees on arbitrage trades?

On Polymarket Global, most standard markets carry zero trading fees making it highly competitive for arb. Polymarket US (the regulated product via FCM intermediaries) charges a flat 0.10% taker fee. The 15-minute crypto markets have their own dynamic fee curve that can be significantly higher to avoid these for cross-platform arb calculations.

Q4: What's the biggest risk in prediction market arbitrage?

Execution failure: filling one side of the trade but being unable to fill the other before the spread closes. This leaves you with an unintended directional position. The second risk is resolution dispute, a market resolving unexpectedly or being voided, leaving one side unhedged. Both are manageable with clear pre-trade rules.

Q5: How much capital do I need to make prediction market arbitrage worthwhile?

Realistically, $3,000–$5,000 minimum across both platforms, with funds pre-loaded and ready to deploy. At lower capital levels, absolute dollar returns on typical 2–4 cent spreads don't justify the time and operational complexity. Arb works best as a complement to an existing trading operation on both platforms.

Q6: Which market categories produce the most Polymarket-Kalshi arbitrage opportunities?

Economic data markets (Fed meetings, CPI releases) and political policy markets consistently produce the most reliable cross-platform discrepancies. The 48-hour window around scheduled announcement events is when spreads are widest and windows are most reliably present.

Q7: How do I calculate Kalshi's fee for a specific contract price?

Kalshi's taker fee formula is: ceil(0.07 × P × (1 − P) × 100) / 100 per contract, where P is the contract price between 0 and 1.

At 50¢ (P = 0.50):0.07 × 0.50 × 0.50 = $0.0175 per contract.

At 38¢ (P = 0.38):0.07 × 0.38 × 0.62 = $0.0165 per contract.

The fee peaks at 50¢ and decreases symmetrically toward 0¢ and 100¢.

Q8: Can I automate Polymarket-Kalshi arbitrage?

Yes and serious practitioners do. Both platforms have APIs. The core logic is: pull live order book data from both platforms, compute YES + NO for every matched market pair, and trigger execution when the sum falls below your threshold minus fees. Execution speed is the primary advantage of automation over manual scanning.