Yes/No arbitrage on Kalshi is arithmetic first and execution second. Every binary contract settles with one side at $1.00 and the other at $0.00, so if the best ask on Yes plus the best ask on No ever sums to less than $1.00, buying both sides locks in the difference at settlement. The math is simple; the hard parts are spotting the window, paying the fees, and getting both legs filled before prices move.
Every binary contract on Kalshi has two sides: Yes and No. By definition, exactly one of them settles at $1.00 and the other at $0.00. If you can buy both sides for less than a dollar combined, you pocket the difference when the contract resolves. Simple math, but the execution is where things get interesting.
This arbitrage exists because Kalshi runs a central limit order book, not an automated market maker. That means prices are set by other traders placing bids and offers. When liquidity is thin or someone makes a mistake, the Yes ask plus the No ask can briefly dip below $1.00. Your job is to spot that gap and hit both sides before it closes.
A few conditions that create these windows:
You can't watch every market manually. Kalshi lists hundreds of contracts across Fed decisions, inflation prints, weather events, and political outcomes. A practical watchlist covers a bounded set of active markets whose order books get checked regularly. Professional desks use screens that calculate implied probabilities across related products; here, you're mostly doing it by hand or writing your own scripts against the Kalshi API documentation.
The basic screen is dead simple: pull the best ask on Yes, pull the best ask on No, add them together. If the sum is less than $1.00, you have a theoretical arb. If it's less than $0.98 or so, you might have something worth trading after fees.
Kalshi charges trading fees and settlement fees that scale with price and market; see the current Kalshi fee breakdown for the exact schedule. A two-cent gross spread can shrink to roughly a penny or less after fees. An arb that only works before fees is not an arb, so do the math before you click.
Slippage is the bigger killer. If you buy Yes and then the No side gets lifted before you can execute, you're stuck holding a directional position you didn't want. Speed matters. Traders who work this strategy keep both order entry windows open side by side so both legs can be fired within a second or two.
A disciplined workflow for a potential arb looks like this:
Most of these opportunities last seconds, not minutes. If you're thinking about it, someone else is already trading it. The edge goes to whoever is watching at the right time and can act fast.
Here is where leg risk bites. You buy Yes at 52 cents, planning to buy No at 46 cents for a clean arb. But by the time you switch screens, the No ask has moved to 50 cents. Now you're in at $1.02 total, which means you're underwater no matter what happens. A textbook arbitrage has turned into a losing directional position.
Your options at that point are bad:
All three outcomes are bad. The cleanest answer is to be disciplined about leg risk. If you can't get both sides filled within your target window, walk away. There will be another opportunity.
Pure Yes/No arbs are rare because other traders are watching for them too. A more common situation is finding contracts where the implied probabilities don't add up across related markets. For example, if Kalshi lists separate contracts for "Fed holds rates in June" and "Fed cuts rates in June" and "Fed hikes rates in June," those three outcomes should sum to roughly 100%. When they don't, you might have a trade.
Source-backed notes on related market checks are posted in the @Kalshi_market Telegram channel, and the discussion chat is a place to pressure-test this kind of logic with other traders before acting on it.
These aren't pure arbitrage plays. They involve some judgment about how the market will re-price as more information comes in. But they're grounded in the same basic insight: binary outcomes have mathematical constraints, and markets sometimes violate those constraints.
Be realistic about the ceiling here. Pure Yes/No arbs on Kalshi are not going to make you rich. The opportunities are small, infrequent, and heavily competed. If you're looking for top Kalshi strategies that scale, you probably need to take directional views on outcomes you actually know something about.
What arb hunting does give you is a way to stay engaged with the order books, learn how prices move, and occasionally pick up a few bucks when someone else makes a mistake. It's a good training ground. It teaches you to think about prices in probability terms and to respect the bid-ask spread.
For a regulated, CFTC-supervised exchange like Kalshi, where everything is KYC'd and settled in USD, having any mechanical edge is valuable. You're not going to find the same mispricings you'd see on offshore books with thinner oversight. But they do happen.
Primary sources I checked (September 12, 2026): CFTC KalshiEX DCM designation (Kalshi is a CFTC-regulated designated contract market), Kalshi API documentation (order book data and rate limits used for scanning), and our Kalshi fee breakdown with the current fee schedule. Rules and fees on those pages control; this page is educational and is not trading advice.
Not often. Windows where the Yes and No asks sum to less than $1.00 after fees are infrequent, and many close within seconds because other traders watch the same order books. They tend to appear during news events or in low-liquidity contracts. Most of the time, there is nothing actionable.
Not strictly. You can scan order books manually on the Kalshi website. To monitor dozens of markets efficiently, a simple script against the documented Kalshi API works: compare the best ask on Yes with the best ask on No and alert when the sum drops below a dollar, while respecting the published API rate limits.
There's no hard minimum, but the opportunities are small in absolute terms. If you're making two cents per contract on a 50-contract arb, that's a dollar before fees. You need enough capital to trade meaningful size, and this works as a supplement to directional trading, not a primary income source.
Yes. If you only get one leg filled and the other side moves against you, you're stuck with a directional position at a bad price. You can also miscalculate fees or get hit by settlement costs you didn't account for. The trade is only riskless if both sides are executed at the prices you planned. Partial fills and execution errors turn it into speculation.
Not financial advice. This site provides educational information only. Trading involves risk, and you can lose money. Verify current market rules and do your own research.