Kalshi arbitrage calculator
- Commission model
- net winnings
- Rate (placeholder)
- 7.0%
- Even money after commission
- 1.930
- Lay bets
- no
- Profit on every outcome
- 3.04
- Total stake
- 100.00
- Sum of implied probabilities
- 97.05%
| Leg | Odds used | Effective odds | Stake |
|---|---|---|---|
| Back Outcome 1 | 2.100 | 2.100 | 49.07 |
| Back Outcome 2 | 2.100 | 2.023 | 50.93 |
| If this wins | Legs that pay | Gross return | Commission | Net profit |
|---|---|---|---|---|
| Outcome 1 | Outcome 1 | 103.04 | 0.00 | 3.04 |
| Outcome 2 | Outcome 2 | 106.96 | 3.92 | 3.04 |
Arbitrage: 3.04% return, 3.04 profit on every outcome
The calculator above is set up for arbitrage involving Kalshi: one leg at a bookmaker with no commission, one leg at Kalshi with 7.0% net winnings applied. Enter your own prices and the stakes for equal profit update as you type.
Why commission matters for arbitrage
An arbitrage exists when the implied probabilities of the effective odds add up to less than 100%. Commission raises every implied probability on the Kalshi side: even money is worth only 1.930 after 7.0%, so the sum creeps up and thin arbitrages disappear. The table shows what a range of Kalshi prices is really worth.
| Odds | Effective | American | Break-even | Net profit on 100 |
|---|---|---|---|---|
| 1.50 | 1.465 | -215 | 68.26% | 46.50 |
| 1.91 | 1.846 | -118 | 54.16% | 84.63 |
| 2.00 | 1.930 | -108 | 51.81% | 93.00 |
| 2.50 | 2.395 | +140 | 41.75% | 139.50 |
| 3.00 | 2.860 | +186 | 34.97% | 186.00 |
| 5.00 | 4.720 | +372 | 21.19% | 372.00 |
| 10.00 | 9.370 | +837 | 10.67% | 837.00 |
Reading the results
The headline figure is the return on total stake; the badge says whether the position is an arbitrage after commission. The stakes table shows what to place on each leg, and for a lay it also shows the backer's stake you need matched, since exchanges ask for that rather than the liability. The outcome table lists, for every possible result, which legs pay, the gross return, the commission taken by Kalshi and the net profit. Rounding mode repeats the calculation with stakes rounded to whole amounts and shows the worst and best outcome, which is the number that matters once real bookmakers are involved.
What to watch
- Prices on Kalshi are set by other traders and move quickly; place the exchange leg first if it is the one more likely to move.
- Commission may apply to your net result across a market, so several bets in the same market share one commission charge.
- Bookmakers may limit accounts that only bet the bookmaker side of arbitrages; rounding stakes to natural amounts helps, and the calculator's rounding mode shows what that costs.
Frequently asked questions
How do I arbitrage between a bookmaker and Kalshi?
Back an outcome at the bookmaker and lay the same outcome at Kalshi, or back the opposite outcome. If the implied probabilities after Kalshi's 7.0% commission sum to less than 100%, the calculator's stakes lock in the same profit on every result.
Why does the calculator apply commission only to the Kalshi leg?
Bookmakers build their margin into the price, so no commission comes off a bookmaker bet. Kalshi charges 7.0% on net winnings, which the calculator applies to that leg only.
How thin an arbitrage is worth taking?
Below about 0.5% the profit is usually smaller than what rounding stakes and price moves cost. The calculator warns at that level and its rounding mode shows the real profit range.
What if the exchange price moves before I place the bookmaker bet?
Place the more volatile leg first, usually the exchange, and re-check the bookmaker price before confirming. Fixed-leg mode in the calculator sizes the second bet around a stake already placed.