A free arbitrage calculator (sure bet calculator) for sports betting. Enter the decimal odds for each outcome and instantly see whether an arbitrage exists, the guaranteed profit percentage, and how to split your total stake so you lock in the same return regardless of the result. Also includes an odds converter and a Kelly Criterion stake calculator.
Looking for live opportunities? OddsFetcher's free arbitrage scanner compares odds across 100+ bookmakers every 5 minutes. Prefer a dedicated sure-bets landing page? See the sure bets finder.
Enter any odds format and instantly see the equivalent in all other formats, plus the implied probability.
Enter the best odds for each outcome to calculate your guaranteed profit. Works for two-way markets (tennis, basketball, over/under) and three-way markets (soccer 1X2 — home win, draw, away win). The calculator divides your total stake proportionally across all outcomes so you lock in the same return no matter which one wins.
Calculate the optimal bet size based on your estimated probability and the odds offered. The Kelly Criterion maximizes long-term bankroll growth while minimizing risk of ruin.
The fastest way to learn arbitrage math is to walk through real numbers. Below are two complete examples — a two-way market and a three-way (soccer 1X2) market — using the exact formulas the calculator applies. Copy any set of odds into the calculator above to check the results yourself.
Suppose two bookmakers price the same tennis match like this:
Step 1 — combined implied probability: (1 / 2.10) + (1 / 2.05) = 0.4762 + 0.4878 = 0.9640 (96.40%). Because the total is below 100%, an arbitrage exists.
Step 2 — guaranteed profit: (1 / 0.9640 − 1) × 100 = 3.73%. On a $1,000 total stake that is a locked-in profit of about $37.35.
Step 3 — stake split: with a $1,000 bankroll, stake $1,000 × (1/2.10) / 0.9640 = $493.98 on Player 1 and $1,000 × (1/2.05) / 0.9640 = $506.02 on Player 2.
Step 4 — verify: $493.98 × 2.10 = $1,037.35 and $506.02 × 2.05 = $1,037.35. Either player wins and you collect the same $1,037.35 — a guaranteed $37.35 (3.73%) no matter who lifts the trophy.
Soccer adds a draw outcome, so you cover three legs across three bookmakers:
Step 1 — combined implied probability: (1 / 2.70) + (1 / 3.50) + (1 / 3.20) = 0.3704 + 0.2857 + 0.3125 = 0.9686 (96.86%) — below 100%, so a three-way arbitrage exists.
Step 2 — guaranteed profit: (1 / 0.9686 − 1) × 100 = 3.24%. On a $1,000 total stake that is $32.43 guaranteed.
Step 3 — stake split: stake $1,000 × (1/2.70) / 0.9686 = $382.38 on the home win, $1,000 × (1/3.50) / 0.9686 = $294.98 on the draw and $1,000 × (1/3.20) / 0.9686 = $322.64 on the away win.
Step 4 — verify: every leg pays $1,032.43($382.38 × 2.70 = $294.98 × 3.50 = $322.64 × 3.20), so the profit is identical whichever of the three results happens.
When there is no arbitrage: if the odds were 2.60 / 3.30 / 3.10 instead, the combined implied probability would be (1/2.60) + (1/3.30) + (1/3.10) = 101.02%. That is above 100%, which is simply the bookmakers' combined margin (vig) — no guaranteed profit is possible at those prices.
These are live arbitrage opportunities our scanner is finding right now across the shared 100+ bookmaker feed. Each row shows the exact odds per outcome — paste them into the calculator above and you will get the same profit percentage. Updated continuously; opportunities disappear as bookmakers rebalance their lines.
Want the full live list? See the real-time arbitrage scanner or the sure bets finder.
An arbitrage calculator (also called a sure bet calculator) tells you whether a set of odds on all outcomes of an event creates a guaranteed profit. Enter the decimal odds for each outcome — if the combined implied probability (1/odds_A + 1/odds_B) is below 100%, the calculator shows the exact profit percentage and how to split your stake across the outcomes to lock in that profit regardless of the result.
An arbitrage exists when (1 / Odds_A) + (1 / Odds_B) < 1. The profit percentage is (1 / combined_implied - 1) × 100. To split a total stake T across outcomes A and B: Stake_A = T × (1/Odds_A) / combined_implied, Stake_B = T × (1/Odds_B) / combined_implied. This equalises your return on every outcome so you profit regardless of the result. OddsFetcher's free arbitrage calculator does all of this automatically.
Yes. OddsFetcher's arbitrage calculator handles both two-way and three-way markets. For a soccer 1X2 market, add the home-win, draw and away-win odds, and the calculator sums the combined implied probability (1/odds_home + 1/odds_draw + 1/odds_away). If the total is below 100%, it shows the guaranteed profit percentage and the exact stake for each of the three outcomes so you profit regardless of the result.
A sure bet (also called an arbitrage or arb) is a combination of odds on all outcomes of an event that creates a guaranteed profit regardless of which outcome wins. Sure bets are rare and usually short-lived — odds shift quickly as the market rebalances. Use OddsFetcher's free scanner to find live sure bets across 100+ bookmakers, refreshed every 5 minutes.
An odds converter translates betting odds between the three common formats — decimal (European), fractional (UK) and American (moneyline) — and shows the implied probability. For example, decimal odds of 2.50 equal +150 American and 3/2 fractional, and imply a 40% probability.
The Kelly Criterion is a bankroll management formula that calculates the optimal fraction to bet given your edge. Kelly fraction f* = (b·p - q) / b, where b is the net decimal odds (odds - 1), p is your estimated win probability, and q = 1 - p. Most professionals stake half-Kelly to lower variance.
Yes. The arbitrage calculator, odds converter and Kelly Criterion calculator on OddsFetcher are free to use, with no sign-up required. The free arbitrage scanner also runs across 100+ bookmakers and refreshes every 5 minutes.