Arbitrage Bet Calculator — Sure Bet Guaranteed Profit

The arbitrage bet calculator finds the exact stakes to place at two different bookmakers so that you profit regardless of which team wins or which outcome occurs. This technique — commonly called arbing or sure betting — exploits pricing differences between bookmakers to guarantee a risk-free return.

Enter three values:

1. Total Stake — the total amount of money you want to commit across both books combined (e.g. $1,000).
2. Decimal Odds at Book 1 (Side A) — the decimal odds offered by the first bookmaker for outcome A (e.g. home team to win at 2.10).
3. Decimal Odds at Book 2 (Side B) — the decimal odds offered by the second bookmaker for outcome B (e.g. away team or draw at 2.10).

The calculator instantly tells you how much to bet on each side, your guaranteed profit in dollars, and the profit as a percentage of total stake. A green badge confirms an arbitrage opportunity; a red badge means no arb exists at the current odds.

All odds must be entered in decimal format. To convert from American: odds of +110 become 2.10; odds of -110 become 1.909. To convert from fractional: 11/10 becomes 2.10 (add 1 to the fraction).

Two-way arbitrage is based on a simple insight: if the sum of the implied probabilities of all outcomes is less than 100%, you can guarantee a profit by backing each outcome proportionally.

1. Implied probabilities:
   impliedA = 1 / decimalOddsA
   impliedB = 1 / decimalOddsB
2. Arbitrage percentage:
   arbPercentage = (impliedA + impliedB) × 100
   Arb exists when arbPercentage < 100. The lower the figure, the larger the profit margin.
3. Optimal stakes (for a given total stake S):
   stakeA = S × impliedA / (impliedA + impliedB)
   stakeB = S × impliedB / (impliedA + impliedB)
   Note: stakeA + stakeB = S (the stakes always sum to your total).
4. Guaranteed profit:
   profit = S × (100 / arbPercentage − 1)
   or equivalently: stakeA × decimalOddsA − S (both outcomes produce the same profit).

The margin (100 − arbPercentage) tells you the profit as a percentage of the total stake. For example, an arb percentage of 95.24% gives a margin of 4.76%, meaning you profit $47.60 on a $1,000 total stake.

Example 1 — Symmetric Two-Way Arb (2.10 / 2.10)

Book 1 offers Team A at 2.10. Book 2 offers Team B at 2.10. Total stake: $1,000.

• impliedA = 1/2.10 ≈ 0.4762; impliedB = 1/2.10 ≈ 0.4762
• arbPercentage = (0.4762 + 0.4762) × 100 ≈ 95.24% — arb confirmed
• stakeA = stakeB = $500 (symmetric odds = equal split)
• Profit if A wins = $500 × 2.10 − $1,000 = +$50
• Profit if B wins = $500 × 2.10 − $1,000 = +$50
• Guaranteed profit: $50 (5.00% return)

Example 2 — Asymmetric Arb (2.50 / 2.20)

Book 1 offers Home Win at 2.50, Book 2 offers Away Win at 2.20. Total stake: $1,000.

• impliedA = 1/2.50 = 0.40; impliedB = 1/2.20 ≈ 0.4545
• arbPercentage = (0.40 + 0.4545) × 100 ≈ 85.45% — strong arb
• stakeA = $1,000 × 0.40 / 0.8545 ≈ $468; stakeB ≈ $532
• Profit if A wins = $468 × 2.50 − $1,000 = +$170
• Profit if B wins = $532 × 2.20 − $1,000 ≈ +$170
• Guaranteed profit: ~$170 (17% return) — a very large arb opportunity.

What Causes Arbitrage Opportunities?

Arbs arise when two bookmakers price the same event differently. Common causes include:

• Stale lines: A book is slow to update after breaking news (injury, weather, lineup).
• Sharp vs. soft books: Sharp books (Pinnacle, Circa) move instantly; soft retail books lag behind.
• Promotional odds: A bookmaker offers a boosted price to attract bettors, creating a temporary arb.
• Model differences: Different algorithms or human traders produce different fair-value estimates.

Most arbs are small (1–3%) and short-lived (minutes). Dedicated arbers use software to scan hundreds of markets simultaneously and place bets the moment an opportunity appears.

Risks and Limitations

While the profit is mathematically guaranteed, practical risks include:

• Account limitations: Bookmakers flag and restrict accounts suspected of arbing. Stake limits are often cut to £2–£5, making arbing uneconomical.
• Bet acceptance delays: Odds may change between placing the first and second bet, turning a profitable arb into a loss.
• Void bets: If one leg is voided (event cancelled, rule 4 deduction), the hedge leg still settles, converting the arb into an open position.
• Capital requirements: Small margins require large stakes to generate meaningful profits.