Arbitrage Betting Calculator

How it works

implied probability of each outcome = 1 ÷ decimal odds · market % = Σ 1/dᵢ (an arbitrage exists when it is below 100%) · stake on outcome i = total × (1/dᵢ) ÷ Σ 1/dⱼ · return = stakeᵢ × dᵢ (equal for every outcome) · profit = total ÷ Σ 1/dⱼ − total

When different bookmakers disagree enough, the best price on every outcome can add up to less than 100% implied probability. Staking each outcome in proportion to its implied probability then returns the same amount whichever outcome wins — more than the total staked. This is an arbitrage or surebet. Rounding stakes to whole units (less conspicuous to bookmakers) shifts the profit slightly between outcomes, so the calculator reports the worst case. Real arbitrage carries risk: odds move before both bets are placed, bets can be voided or limited, and bookmakers may close accounts.

Worked example

With $1,000 to stake on a tennis match at 2.10 and 2.05, the market is 47.62% + 48.78% = 96.40%, an arbitrage. Stake $493.98 at 2.10 and $506.02 at 2.05: the first returns $1,037.36 and the second $1,037.34, so the guaranteed profit is at least $37.34 (3.73%).

Sources: Wikipedia — Arbitrage betting · NCPG — Responsible gambling

Frequently asked questions