Arbitrage Calculator
When two sportsbooks disagree enough on the same market, the best price on each outcome can add up to less than 100% implied probability. This calculator checks that, splits your stake so every outcome pays the same, and shows the result.
These prices leave a gap of 1.71%. Splitting $1,000 as shown gives about +$15.00 whichever side wins.
- Bet on Side Aat +105
- $495
- Bet on Side Bat +102
- $500
- If Side A wins
- +$19.75
- If Side B wins
- +$15.00
- Margin1 − the sum of the implied probabilities
- +1.71%
- Total staked
- $995
- Return on staked
- +1.51%
Calculated at the odds you entered. Prices move and bets can be voided, so confirm both prices before placing either bet. HedgeMath doesn't place bets.
How the math works
Each price has an implied probability: 100 ÷ (odds + 100) for positive odds, and |odds| ÷ (|odds| + 100) for negative odds. The margin is 1 minus the sum of the probabilities for all outcomes. A positive margin means the prices leave a gap.
To split a stake T, bet each outcome in proportion to its implied probability: stake_i = T × p_i ÷ sum of p. Every outcome then pays the same total.
The result is that total payout minus everything you staked. Rounding stakes down to whole amounts changes it slightly, which the calculator includes.
Worked example
Load this example into the calculator →- Total to stake
- $1,000
- Best odds on side A
- +105
- Best odds on side B
- +102
- Round stakes down to
- Nearest $5
These prices leave a gap of 1.71%. Splitting $1,000 as shown gives about +$15.00 whichever side wins.
Calculated with the same engine as the calculator above. Last updated 2026-09-30.
What changes the result
- Most gaps are small or short-lived
- Sportsbooks update prices constantly, so a gap can close before both bets are placed.
- A very large gap is often a mistake
- Prices that look too good can be errors, and sportsbooks can void bets placed at erroneous prices.
- Same market, same line
- Both sides must be the same market with matching lines, in the same game.
- Limits and account rules
- Sportsbooks set stake limits and can restrict accounts. Check each book's rules.
Frequently asked questions
What is arbitrage in sports betting?
It's when the best available prices across sportsbooks for every outcome of a market add up to less than 100% implied probability, so betting every outcome in the right proportions returns more than you staked.
How do I calculate the stake on each side?
Bet each outcome in proportion to its implied probability. The calculator does this and rounds the stakes down to the increment you choose.
Why does the calculator show no gap?
Most of the time the combined prices leave the sportsbooks a margin, so the sum of the implied probabilities is above 100% and no split comes out ahead.
Is the result locked in?
Only at the prices entered. Prices move between placing the first and second bet, and sportsbooks can void or limit bets.
Does HedgeMath place the bets?
No. You place every bet yourself.
Skip the searching.
Pro+ (coming later) will add a live arbitrage scanner across your books.
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