Prediction markets · Guide
Kalshi Arbitrage: The Complete Guide
How to turn Kalshi prices into odds, what Kalshi's fees really cost, and how to lock in a profit against sportsbooks and Polymarket, with worked examples you can check yourself.
Key facts
- A Kalshi contract pays $1 if its outcome happens. Its price is the market's probability.
- Decimal odds = 1 / price. A 52¢ contract is 1.92 before fees and 1.86 after the standard fee.
- Standard fee: 0.07 × C × P × (1 − P), rounded up to the next cent. MLB series pay half.
- Kalshi works like an exchange: you trade against other users, not against the house.
- Most opportunities are small, around 1% to 2%. Matching settlement rules matters more than the math.
What Kalshi is
Kalshi is a US exchange for event contracts, regulated by the Commodity Futures Trading Commission (CFTC). Every contract asks a yes-or-no question, such as "Will the Lakers win tonight?" If the answer is yes, each YES contract pays $1. If the answer is no, it pays nothing, and the NO contract pays $1 instead.
Prices run from 1¢ to 99¢. Because the payout is always $1, the price is the market's estimate of the probability. A contract at 52¢ says the market sees about a 52% chance.
Sports and short-term crypto markets make up most of Kalshi's trading volume. Game winners, spreads, totals and player props sit next to economics, politics and crypto markets. Outside the US, Kalshi is available in many countries through its website, but not everywhere. The UK, Canada, Australia and Ireland are among the places it does not serve.
Why Kalshi matters for arbitrage
A sportsbook sets its own prices and takes the other side of your bet. When you win consistently, it loses money, so it limits your account. That is the biggest practical problem in arbitrage betting.
Kalshi works differently. You trade against other users, and Kalshi earns a fee on each trade. It does not take the other side of your position, so your winning does not cost Kalshi anything. In that sense it behaves like a betting exchange such as Betfair or Smarkets.
This matters most in the United States, where betting exchanges are almost unavailable. For a US bettor, Kalshi is the closest thing to an exchange: a place to cover the second leg of an arbitrage without worrying that winning will get the account limited.
Turning Kalshi prices into odds
Sportsbooks show odds. Kalshi shows prices. To compare them, convert the price into decimal odds:
A 52¢ contract equals decimal odds of 1 / 0.52 = 1.92. In American odds that is about −108.
That raw number ignores the fee, and the fee is never zero for a normal order. Add the fee per contract to the price first, and you get the odds you really receive:
At 52¢ the fee is about 1.75¢ per contract, so the effective odds are 1 / 0.5375 = 1.86. That is the number to compare with a sportsbook.
| Price | Fee per contract | Odds before fee | American | Odds after fee | American |
|---|---|---|---|---|---|
| 10¢ | 0.63¢ | 10.000 | +900 | 9.407 | +841 |
| 20¢ | 1.12¢ | 5.000 | +400 | 4.735 | +373 |
| 30¢ | 1.47¢ | 3.333 | +233 | 3.178 | +218 |
| 40¢ | 1.68¢ | 2.500 | +150 | 2.399 | +140 |
| 45¢ | 1.73¢ | 2.222 | +122 | 2.140 | +114 |
| 50¢ | 1.75¢ | 2.000 | +100 | 1.932 | −107 |
| 55¢ | 1.73¢ | 1.818 | −122 | 1.763 | −131 |
| 60¢ | 1.68¢ | 1.667 | −150 | 1.621 | −161 |
| 70¢ | 1.47¢ | 1.429 | −233 | 1.399 | −251 |
| 80¢ | 1.12¢ | 1.250 | −400 | 1.233 | −430 |
| 90¢ | 0.63¢ | 1.111 | −900 | 1.103 | −967 |
Kalshi fees, explained
Kalshi charges a fee on the expected earnings of each contract. The fee is highest when the price is near 50¢, where the outcome is most uncertain, and shrinks toward the extremes.
C is the number of contracts and P is the price in dollars. The total fee on each trade is rounded up to the next cent, so 200 contracts at 52¢ cost a $3.50 fee, not $3.49.
| Fee | Rate | When it applies |
|---|---|---|
| Taker | 0.07 | Your order fills immediately against a waiting order. Almost all sports series. |
| Taker, MLB | 0.035 | Pro baseball series, which run at a 0.5 fee multiplier. |
| Maker | 0.0175 | Your order waits on the order book and fills later, in series that charge maker fees. These include major league games. |
| Maker, other series | 0 | Resting orders in series without maker fees. |
| Settlement and bank transfers | $0 | No settlement fee. ACH deposits and withdrawals are free. Card deposits cost up to 2%. |
Maker orders are cheaper, but there is no guarantee they fill. In arbitrage, an unfilled leg leaves you holding one side of the trade, so most arbitrage traders pay the taker fee and accept the cost. The full breakdown, with a fee calculator, is in Kalshi fees explained.
Do the math for any price, fee rate and stake.
Open the Kalshi arbitrage calculatorKalshi vs a sportsbook, step by step
This is the most common Kalshi arbitrage. You buy one outcome on Kalshi and bet the other outcome at a sportsbook. It works cleanly on two-outcome markets such as an NBA or NFL game winner.
- Find the two prices. The sportsbook's odds on Team A, and Kalshi's price on "Team B wins".
- Convert Kalshi to effective odds using the fee, as shown above.
- Add the implied probabilities. If 1 / sportsbook odds plus Kalshi's price including the fee is below 100%, there is an arbitrage.
- Size the trade. Pick a number of Kalshi contracts. Each pays $1, so to make the sportsbook side pay the same, stake contracts ÷ sportsbook odds.
- Place the riskier leg first. Usually that is the sportsbook bet, because sportsbooks move and limit faster. Then buy the Kalshi contracts.
Notice how much the fee matters. Without it, the Kalshi side would look like odds of 1.92 and the margin like 3.7%. The real margin is less than half of that.
Kalshi vs Polymarket
Polymarket is a second prediction market, running on a dollar-pegged digital currency. Many questions trade on both platforms. When YES on one platform plus NO on the other costs less than $1, every pair pays exactly $1 whatever happens.
Polymarket uses the same fee formula as Kalshi, with a sports rate of 0.05, but on a buy it takes the fee in shares, so you buy slightly more shares than you need to keep. Funding Polymarket's international platform means converting money into its digital currency and back, which can cost more than the trading fee itself. For a full side-by-side, see Kalshi vs Polymarket.
Where opportunities show up
Be realistic about size. An analysis by Blockworks Research found that in the 72 hours before major games, Kalshi and FanDuel prices differed by about 0.54% on average, and moved almost in lockstep once games started. Big, easy gaps on headline markets do not last.
Opportunities tend to come from moments and markets where one side updates more slowly:
- News moments. Injury news or lineup changes can move a sportsbook and Kalshi at different speeds.
- Less-traded markets. Props, totals and smaller leagues get less attention than game winners.
- Lower-fee series. MLB series pay half the standard fee, which turns some borderline gaps into real ones.
- Many sportsbooks. The more books you hold accounts with, the more often one of them disagrees with Kalshi.
The 1% rule of thumb applies here too. A margin under 1% leaves almost no room for a price move or a deposit fee.
Risks and checks before every trade
The biggest risk is not the math. It is settlement rules. Both legs must be decided by exactly the same rules, or you are holding two separate bets.
- Settlement rules. Read the rules of the Kalshi market and the sportsbook market. Does overtime count? What happens if the game is postponed or abandoned? In soccer, a draw settles "Team A wins" as NO on Kalshi, while a sportsbook's draw-no-bet market refunds your stake on a draw. One difference turns an arbitrage into a gamble.
- Order book depth. The price you see may cover only a few contracts. A larger order fills partly at worse prices. Check the depth before the first leg.
- Price moves between legs. If the second price moves after the first leg is placed, recalculate the second stake instead of re-splitting the whole trade.
- Money locked until settlement. Kalshi contracts tie up cash until the market settles, unless you sell the contracts earlier.
- Funding costs. Card deposits on Kalshi cost up to 2%, and Polymarket needs a currency conversion. Use free funding methods where you can, or the fees eat the margin.
- Availability. Kalshi is not open in every country, and some markets are not open everywhere it operates. Check that your account can trade the market before you place the sportsbook leg.
Tools
You can find opportunities by hand by comparing a sportsbook's odds with Kalshi's prices, but it is slow. These tools help:
- Kalshi arbitrage calculator: Kalshi vs sportsbook, Kalshi vs Polymarket, and a price-to-odds converter, with the real fee formula.
- Arbitrage calculator: for sportsbook-only arbitrage, exchanges, free bets and re-hedging.
- Best arbitrage betting software: scanners that find arbs across 100+ bookmakers for you, compared.
FAQ
What is Kalshi arbitrage?
Buying a Kalshi contract on one outcome and covering the other outcome elsewhere, such as at a sportsbook or on Polymarket, at prices that together cost less than the payout after fees. The profit is locked in whichever outcome happens.
How much does Kalshi charge per trade?
The standard taker fee is 0.07 × contracts × price × (1 − price), rounded up to the next cent. That is about 1.75¢ per contract at 50¢. MLB series use half that rate. Resting maker orders pay 0.0175 in series with maker fees and nothing in the others.
How do I convert a Kalshi price into odds?
Divide 1 by the price in dollars. 52¢ is 1.92. Add the fee per contract to the price first to get the odds you really receive: 1 / (0.52 + 0.0175) = 1.86.
Can you arbitrage Kalshi and Polymarket?
Yes, when YES on one platform and NO on the other cost less than $1 together after both fees, and both platforms settle the question by the same rules.
Does Kalshi limit winning traders like sportsbooks do?
Kalshi does not take the other side of your trades. You trade against other users and Kalshi earns a fee on each trade, so it has no reason to limit you for winning the way a sportsbook does.
How much can you make with Kalshi arbitrage?
Most opportunities are around 1% to 2% of the money committed. Profit comes from repeating small trades with discipline, not from one big win.
Is Kalshi available in my country?
Kalshi serves the United States and many other countries through its website. It is not available in some countries, including the UK, Canada, Australia and Ireland. Check Kalshi's member agreement for the current list.