Comparator
Kalshi vs Polymarket Arb Scanner
Daily scan of arbitrage candidates across Kalshi + Polymarket. Paired contracts, fees + slippage overlay, resolution risk notes. Browser-only. Free.
- Inputs
- Scenario form
- Runtime
- Instant
- Privacy
- Client-side · no upload
- API key
- Not required
- Methodology
- Open →
How to use
Step-by-step
- 1
The tool polls both platforms and lists current cross-venue spreads on equivalent-event pairs.
- 2
Read the gross spread and net spread (after fees, gas, capital costs). Net spreads under 1% are usually not worth the operational complexity.
- 3
Verify event equivalence on the methodology page — subtle differences in resolution criteria can void apparent arbs.
- 4
Check the depth of book on both venues. Apparent arbs with thin depth disappear at meaningful size.
- 5
Read disclaimers. The tool surfaces opportunities; it does not recommend execution. Real arb requires capital on both sides and operational tolerance for settlement delays.
For agents
Use in an agent
Same math, same result shape as the UI above — as a static ES module. No HTTP request, no auth, no rate limit.
import { compute } from "https://aifinhub.io/engines/kalshi-poly-arb.js";Contract: /contracts/kalshi-poly-arb.json Full agent guide →
Glossary references
Terms used by this tool
Questions people ask next
FAQ
What's Kalshi-Polymarket arbitrage?
When the same underlying event is listed on both Kalshi (CFTC-regulated US prediction market) and Polymarket (offshore decentralized market), prices can diverge briefly. If Kalshi shows YES at $0.55 and Polymarket shows YES at $0.50, buying Polymarket and selling Kalshi locks a $0.05 profit minus fees. The tool finds and sizes these opportunities.
Why doesn't the arbitrage close instantly?
Three frictions: (1) cross-platform capital movement is slow (days, not minutes), (2) Kalshi requires US KYC; Polymarket requires crypto wallet — different user bases, (3) liquidity is thin on both sides. Arbs persist for hours-days, not seconds. The tool's 'recommended size' field accounts for slippage.
What fees does the calculator include?
Kalshi's 5% on profit (no fee on losses), Polymarket's 0% market fee but +/- gas costs (typically $1-3 per trade as of asOfDate). USDC bridging cost (variable). The methodology page lists per-fee components.
Are the events actually equivalent?
The tool only flags a pair when the resolution criteria match exactly (same source, same threshold, same date). Subtle differences — e.g., Kalshi's 'will Fed raise rates by July 31' vs. Polymarket's 'will Fed raise rates in July' — count as different events even if they often resolve the same way. The methodology page shows the event-matching algorithm.
Should I actually trade these?
Read the disclaimer. The tool surfaces opportunities; it doesn't recommend execution. Real-world arb requires capital on both platforms, KYC on both sides, and willingness to wait through resolution. Many surface arbs are not actually profitable after settlement-time-discounted capital cost.
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