Arbitrage arithmetic: allocation, cents and settlement risk

Why this matters

The word surebet can conceal assumptions. This tool allocates a total stake across a complete set of mutually exclusive outcomes, then checks the smallest net result after rounding to cents. It cannot place or reserve any of those prices.

Before entering the numbers

The word surebet can conceal assumptions. This tool allocates a total stake across a complete set of mutually exclusive outcomes, then checks the smallest net result after rounding to cents. It cannot place or reserve any of those prices.

Open the calculator: Arbitrage / Surebet Calculator. All figures below are hypothetical. CU denotes a consistent currency unit, not a named currency. Field and result names match the English calculator interface.

Prices of 2.10: modelled net result +5 CU

Use 100 CU and two decimal prices of 2.10. Both outcomes receive 50 CU in this symmetric example. The positive modelled result exists only while both entered prices and matching settlement assumptions hold.

Entered fields: Total stake: 100 (CU) · Decimal odds, separated by commas: 2.10, 2.10 (2–100 outcomes; each >1 and ≤1,000,000)

Calculated results: Reciprocal probability sum: 95.24 % · Minimum modelled net result: 5.00 CU · Minimum modelled return on stake: 5.00 % · Outcome 1: stake: 50.00 CU · Outcome 2: stake: 50.00 CU · Outcome 1: net result: 5.00 CU · Outcome 2: net result: 5.00 CU

• S = 1/2.10 + 1/2.10 = 0.952381
• 100 × (1/2.10) / S = 50 CU per outcome
• 50 × 2.10 − 100 = 5 CU

Prices of 1.90: modelled net result −5 CU

Replace both prices with 1.90. The same equal allocation now produces a negative net result for either outcome. Equalising the returns does not turn an unfavourable price set into a favourable one.

Entered fields: Total stake: 100 (CU) · Decimal odds, separated by commas: 1.90, 1.90 (2–100 outcomes; each >1 and ≤1,000,000)

Calculated results: Reciprocal probability sum: 105.26 % · Minimum modelled net result: -5.00 CU · Minimum modelled return on stake: -5.00 % · Outcome 1: stake: 50.00 CU · Outcome 2: stake: 50.00 CU · Outcome 1: net result: -5.00 CU · Outcome 2: net result: -5.00 CU

• S = 1/1.90 + 1/1.90 = 1.052632
• 50 × 1.90 − 100 = −5 CU

What the result leaves out

Incomplete outcome coverage, rejected stakes, price movement, commission, limits and different void rules can invalidate the comparison. More outcomes also introduce cent-rounding differences; the calculator reports the minimum rounded result.

Arithmetic uses unrounded intermediate values; displayed numbers are rounded. These examples document the model, not a provider quote or an observed transaction.

18+. Educational information only. This is not financial, investment, legal or tax advice, and it is not a guarantee of any result. Betting, gambling and crypto involve a risk of losing money. Estimates depend on your inputs; verify current provider terms and local rules.

Practical checklist

• Verify that the outcomes are mutually exclusive and cover the entire market.
• Confirm that the settlement rules are identical for all legs.
• Check that the odds are accepted for all legs and that limits are sufficient.
• Include fees and assess the unhedged exposure if any leg is rejected.