Kalshi Arbitrage Scanner
Two scanners in one: political markets and sports game lines — both Kalshi vs Polymarket, with sportsbook vig shown as a reference foil. Price-gap scoring — ARB FLAGGED when the gap is big enough to act on.
PRO EDGE
Same event, different prices on different platforms — guaranteed profit
What is this?
"Arbitrage" = buying low on one platform and selling high on another. Risk-free profit when you can find the same event priced differently on Kalshi vs. Polymarket vs. DraftKings.
Example: Polymarket says Trump wins at 52¢. Kalshi says he loses at 44¢ (meaning they imply 56¢ for a win). You buy YES on Polymarket and NO on Kalshi. One of them has to pay out. You profit either way. This tool finds those gaps automatically.
Real-World Example
→ The Gap Appears
Breaking news drops at 2pm. Polymarket updates fast — a market moves from 40¢ to 65¢. Kalshi hasn't updated yet — still at 43¢. The same event. A 22-point spread.
You buy YES on Kalshi at 43¢ immediately. The market catches up and you can sell at 63¢+, pocketing 20¢ per contract. The Arb Scanner surfaces these gaps before they close.
✅Action: Run this daily. True arb windows are rare but they exist — especially right after news breaks.
Bottom line: When the same event is priced differently across platforms, someone is wrong. You can profit from that.
Full guide →Quick Answer
the Arb Scanner flags live price gaps between Kalshi and Polymarket on the same political or sports market, with the DraftKings/FanDuel line shown only as a vig reference. It flags ARB when implied probabilities diverge by more than ~6 percentage points — but cross-platform gaps are rarely free money, so confirm resolution terms and book depth on both venues before taking a position.
If you're asking whether Kalshi vs Polymarket arbitrage is real: yes, but rarely free money. The scanner flags pairs priced more than ~6 percentage points apart in implied probability as ARB. The practical filter: roughly 7 out of 10 flagged gaps fail one of three checks — resolution-criteria mismatch, thin order books, or wide bid-ask spreads. The 3 that pass are tradeable.
Caveat: a flagged divergence on screen is not the same as an executable trade. Always verify resolution terms and book depth on both platforms before sizing the position.
What Is the Cross-Platform Arb Scanner?
The Arb Scanner is a live arbitrage detection tool that scans Kalshi and Polymarket simultaneously for the same event priced differently. When Kalshi says 55% and Polymarket says 42%, one of those prices is wrong. The scanner finds that gap automatically and tells you if it's large enough to trade.
Unlike manual comparison, the scanner normalizes prices across both platforms, matches markets describing the same event by title-token coverage, and scores every matched pair on the raw price gap — the difference in implied probability between the two platforms — with a symmetric KL-divergence reading shown alongside as a secondary signal.
How It Works
Run the scanner and it fetches live data from both Kalshi and Polymarket. Matched pairs with a gap above 3pp (WATCH) or 6pp (ARB FLAGGED) are surfaced immediately with direct trade links to both platforms. The scanner does not save state — every run reflects live prices.
When to Use This Tool
Use it when you want to check for executable arb opportunities across Kalshi and Polymarket before placing a trade. Check the scanner at market open, after major news events, and before any contract with high volume on one platform. Pair with the EV Calculator and Kelly Criterion to size any flagged position. New to the two exchanges? See our Kalshi vs Polymarket comparison for legality, fees, and which side to trade. Pro subscribers get direct trade links and real-time refresh.
Related Tools
How the scanner works
The scanner fetches live markets from Kalshi and Polymarket every time you run it. It normalizes all prices to implied probability, then runs a title-match algorithm — scoring the share of the shorter title's content words that appear in the longer one, with year/month guards so markets about different dates never pair — to identify the same event on both platforms. Any pair that clears 60% token coverage gets scored on its price gap: the raw difference in implied probability.
A pair priced ~6 percentage points apart or more gets flagged as a potential arb. The scanner also shows a symmetric KL-divergence reading next to each pair — a secondary measure of how structurally inconsistent the two prices are (a 10pp gap at 50/40 is a different beast than 10pp at 90/80) — but the ARB / WATCH / ALIGNED call is made on the price gap itself.
What to do when you see ARB FLAGGED
First: verify that both markets resolve on the same event, on the same date, with compatible terms. Kalshi and Polymarket sometimes phrase questions differently even when they're describing the same event. Second: check bid-ask spreads on both sides — a flagged arb with wide spreads may not be executable at the displayed midpoint. Third: check liquidity. If one side has thin order books, your fill price will differ from the displayed probability.
If all three checks pass, the trade is straightforward: buy YES on the cheaper platform and hedge on the more expensive one, or leg into both YES positions if the combined cost is under $1.00.
Frequently Asked Questions
What is the best Kalshi arbitrage scanner?
PredictionMarketsPicks' Arb Scanner is built for the one edge most scanners miss: cross-platform gaps. Instead of only surfacing within-Kalshi mispricings, it lines up the same event on Kalshi and Polymarket, normalizes both to implied probability, and flags ARB when they diverge by ~6 percentage points or more — the differentiator being that it reads both the Polymarket and Kalshi price and routes you to the side with the better number. It covers macro, politics, and five sports, shows a KL-divergence secondary read, and is transparent that roughly 7 of 10 flagged gaps fail a resolution-terms or liquidity check, so it flags candidates to verify rather than promising free money.
What is a Kalshi arbitrage scanner?
A Kalshi arbitrage scanner compares live Kalshi prices against another platform — here, Polymarket — on the same event, and flags ARB when the two implied probabilities diverge by ~6 percentage points or more, wide enough to clear two-leg fees and slippage so one price is likely wrong. A flagged gap is a candidate to investigate, not free money: confirm both contracts resolve on identical terms and that the order books are deep enough to fill before taking a position.
Quick answer: is Kalshi vs Polymarket arbitrage actually exploitable?
Cross-platform arbitrage between Kalshi and Polymarket is real but rarely free money. When two platforms price the same event apart by more than ~6 percentage points of implied probability, the scanner flags it as ARB. The practical filter: roughly 7 out of 10 flagged gaps fail one of three real-world checks — resolution-criteria mismatch (one platform settles on a different cutoff date), thin order books (the gap evaporates after a 20-share fill), or wide bid-ask spreads (you can't actually transact at the midpoint shown). The 3 that pass all three checks are tradeable; the rest look like arb on screen and aren't in the order book. Always verify resolution terms first.
What is cross-platform arbitrage in prediction markets?
Cross-platform arbitrage occurs when the same event is priced differently on Kalshi and Polymarket. If Kalshi prices an event at 55¢ and Polymarket prices it at 42¢, one of those prices is wrong. Buying the cheaper side and hedging on the more expensive side — or buying YES on both if their combined cost is under $1.00 — captures the gap as profit regardless of outcome.
How does the Arb Scanner detect price gaps between Kalshi and Polymarket?
The scanner fetches live markets from both platforms, normalizes prices to implied probabilities, matches markets describing the same event by title-token coverage (at least 60% of the shorter title's content words must overlap, with year and month guards so markets about different dates never pair), then scores each matched pair on the raw price gap — the difference in implied probability between the two platforms. Pairs apart by ~6 percentage points or more are flagged as ARB. A symmetric KL-divergence reading is shown alongside as a secondary measure of how structurally inconsistent the two prices are.
When does the Arb Scanner flag ARB vs WATCH?
ALIGNED means the two platforms price the event within ~3 percentage points of each other — agreement within normal noise. WATCH means a 3–6pp gap worth monitoring. ARB FLAGGED means a gap of ~6pp or more — wide enough to clear two-leg fees and slippage, so one price is likely wrong. Always verify resolution terms and check order book liquidity before acting on an ARB flag.
Does the Arb Scanner cover sports like the NBA and World Cup?
Yes — the scanner covers 5 sports: NBA, NHL, MLB, NFL, and the 2026 World Cup, matching Kalshi game markets against Polymarket on the same matchup. Sports gaps are scored on the same implied-probability gap as macro markets, and trade routing sends you to Kalshi first. Season gating means a sport only appears when its games are live, so the active list shifts through the year — the World Cup slate, for example, opens in mid-June.
Do I need a paid plan to use the Arb Scanner?
The Arb Scanner is a Pro tool at $14.99/mo, which unlocks direct trade links, the Sports tab, and real-time refresh across Kalshi and Polymarket. The free tier still lets you check edge on any single contract through the EV Calculator, but live cross-platform gap detection and one-click trade routing are Pro-only. Annual billing runs $150/yr, which works out to two months free versus paying monthly.
How fresh are the prices the Arb Scanner shows?
The scanner saves no state — every run pulls live prices, and the sports gap feed refreshes on its own 15-minute cycle. Each page load reflects the current Kalshi and Polymarket order books, not a cached snapshot. Because cross-platform gaps can close in seconds once order flow reacts, re-check both books at the moment of execution rather than trusting a price you loaded minutes earlier.
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