What is arbitrage betting?
Arbitrage betting is backing both sides of the same bet at two different venues, at prices that add up to less than a certainty. If one venue prices the over at +112 and another prices the under at −104, the two implied probabilities sum to about 98% — and a market that sums to less than 100% is one you can take both halves of. Split the stake in proportion to the two prices and the same amount comes back whichever way the game goes. Either way, you win the difference.
Nothing about that depends on being right. You are not predicting the outcome, you are taking advantage of two venues disagreeing about it, which is why arbitrage sits apart from every other angle on this site. What it does depend on is both prices still being there when you get to them, both venues accepting the stake you want to place, and the arithmetic being done net of what each venue charges rather than on the posted numbers. Those three conditions are where real positions are won and lost, and they are what the board below is built around.
How the arb finder works
BeatVig prices the same bets at the sportsbooks, at the prediction markets and at the matched-wager exchanges. The scan behind this live arbitrage betting tool walks every bet on that board, takes the best price on each side from a different venue, and asks one question: do the two implied probabilities add up to less than one?
Three rules decide whether the answer gets published. The two legs must be on the identical line — a half point apart is a different bet and pairing them is how a sports arbitrage finder invents positions that do not exist. Both prices must have been repriced by their venue within 5 minutes, and within 2 minutes of each other, so the pair was true at the same moment rather than one venue's number from this minute against another's from an hour ago. And the margin is computed net of each venue's published fee, not on the posted prices — a position that only exists before Kalshi's per-contract fee is not a position.
Anything failing a test is not shown at all, never shown greyed out with a caveat. An empty board is a correct answer and is the usual one.
Live arbitrage bets right now
Scanned continuously across every sport BeatVig prices. This board is usually empty, and that is the honest state of the market rather than a failure of the scan.
These decay in minutes. An arbitrage is a snapshot of two prices that were live moments ago, and it decays in minutes — often in seconds once either venue notices. Confirm BOTH prices at BOTH venues before staking either leg. A position with one leg filled and the other gone is not an arbitrage; it is a one-sided bet you did not intend to make. Venues also limit, void or refuse stakes at their discretion, so the profit is guaranteed by the arithmetic and by nothing else.
Both legs of every position below were repriced by their venue within 5 minutes, and within 2 minutes of each other. Anything that fails either test is not shown at all — never shown greyed — and every price is net of the venue's own trading fee.
No arbitrage on the board right now
Premium shows both sides of each position: the bet, the venue and price for each leg, how to split a $100.00 stake, and what it returns either way. The count above is live and is usually zero — arbitrage is rare, which is the point of watching for it.
Go PremiumKalshi and Polymarket vs sportsbook arbs
Most of what this board finds is between a prediction market and a sportsbook, and the reason is structural. A sportsbook sets a price and keeps its margin inside it, so both of its own sides are shaded and they rarely disagree with each other. Kalshi and Polymarket are exchanges: the price is whatever two traders last agreed on, the fee sits outside it, and a contract can drift on light volume while the book it is being compared against has not moved at all. That drift is the gap.
It also means the fee arithmetic is not optional. Kalshi charges a per-contract fee that is largest on contracts priced near a coin flip, which is exactly where most two-sided positions sit. Polymarket charges a small capped fraction. Novig charges nothing on a pregame straight trade, on either side. A sportsbook charges nothing separate at all, because its margin is already in the number — which is not the same sentence as "a sportsbook is free". Every margin on this board is computed after all of that.
The one other thing an exchange leg brings is depth. A book will take a normal stake at the number it posted; an order book is only good for the size resting behind it, and a stake larger than that fills at a worse average. Take the exchange leg first.
Arbitrage vs middles vs +EV
These three get used interchangeably and they are three different bets. An arbitrage covers both outcomes of the same bet on the same line, so one leg always wins and the other always loses, and the return is the difference between what you staked and what comes back. A middle takes two prices on different lines — over 4.5 at one venue, under 5.5 at another — so both legs can win if the result lands between them, and both can lose if it does not. A middle is a bet with an attractive shape; it is not a two-sided position, and this board discards a pair that is not on the identical line rather than publishing it as one.
Positive expected value is different again: one bet, one side, taken because the price is better than the outcome is worth. It wins more often than it loses over a long run and says nothing about any individual bet. That is what the edge board ranks. Arbitrage is scarcer and smaller per position; +EV is available every day and needs patience instead of speed.
Arbitrage betting FAQ
What is arbitrage betting?
Arbitrage betting is backing both sides of the same bet at two different venues at prices that add up to less than a certainty, so the same amount comes back whichever side wins. The profit is the difference between the total staked and the total returned, and it does not depend on predicting the outcome.
Is arbitrage betting legal?
Yes. Arbitrage betting is legal everywhere sports betting itself is legal, because it is placing two ordinary bets at two ordinary venues. What it can breach is a sportsbook's own terms of service, which typically allow the book to limit or close an account at its discretion rather than making the bet itself unlawful.
Is arbitrage betting allowed on Kalshi?
Yes. Kalshi is a CFTC-regulated exchange and taking both sides of related contracts is ordinary trading there rather than a prohibited strategy. Kalshi earns a per-contract fee on volume rather than on your losses, so it has no reason to restrict an account for trading profitably.
How much can you make from arbitrage betting?
Real two-sided positions on public venues run from a fraction of a percent to low single digits of the total staked, so a $100 round trip typically returns one to three dollars. Anything above about eight percent is treated as a data problem rather than an opportunity and is withheld from this board.
How do you calculate an arbitrage bet?
Convert both prices to implied probability and add them together. If the total is below 100%, the gap is the margin, and each leg's stake is its own implied probability divided by that total. Both legs then return the same amount whichever side wins.
How long does an arbitrage opportunity last?
Usually minutes, and often seconds once either venue notices. Both boards are watched by people doing exactly this, which is why this finder refuses any pair whose two prices were not repriced within five minutes and within two minutes of each other.
How do you arbitrage bet without getting limited?
Sportsbooks limit accounts whose betting pattern looks like trading: round stakes at the exact posted number, always on the side that just moved, always minutes after it moved. Varying stake sizes, betting some ordinary markets alongside, and taking the exchange side of a position rather than the book side all reduce that signal. No approach removes it, because the book decides.
Do arbitrage calculators account for exchange fees?
Most do not. A standard arbitrage calculator divides the two posted prices and reports the margin, which overstates the result on any Kalshi, Polymarket or ProphetX leg because those venues charge outside the quote. BeatVig's arbitrage calculator applies each venue's published fee schedule before reporting the margin.