Why the Calculator Matters
Placing the wrong stake allocation turns a guaranteed profit into a loss. The arbitrage calculator is the single most important tool in your arbing toolkit — and understanding the maths means you can double-check any software's output.
Two-Way Arb Formula (e.g. Tennis, Head-to-Head)
For a two-outcome market (Outcome A and Outcome B):
Step 1 — Check for an arb:
Arb% = (1 / Odds_A + 1 / Odds_B) × 100
If Arb% < 100, you have a profitable opportunity. The lower the percentage, the higher the profit.
Step 2 — Calculate your margin:
Profit margin = 100 − Arb%
Step 3 — Calculate stakes (for a total outlay of S):
Stake_A = S × (1 / Odds_A) / (1 / Odds_A + 1 / Odds_B) Stake_B = S × (1 / Odds_B) / (1 / Odds_A + 1 / Odds_B)
Step 4 — Verify:
Return if A wins = Stake_A × Odds_A Return if B wins = Stake_B × Odds_B
Both should equal the same amount (your guaranteed return).
Worked Example
- —Player A odds: 2.15 (Bookmaker 1)
- —Player B odds: 2.10 (Bookmaker 2)
- —Total stake budget: £200
Arb% = (1/2.15 + 1/2.10) × 100 = (0.4651 + 0.4762) × 100 = 94.13%
Profit margin = 100 − 94.13 = 5.87%
Stake_A = 200 × (0.4651 / 0.9413) = £98.91 Stake_B = 200 × (0.4762 / 0.9413) = £101.09
Return if A wins = 98.91 × 2.15 = £212.66 Return if B wins = 101.09 × 2.10 = £212.29
Your guaranteed profit is approximately £12.47 on a £200 investment — a 6.2% return.
Three-Way Arb Formula (e.g. Football 1X2)
For three outcomes (Home Win, Draw, Away Win):
Arb% = (1/Odds_Home + 1/Odds_Draw + 1/Odds_Away) × 100
If Arb% < 100, you have an arb. Stakes are calculated the same way:
Stake_i = Total_Stake × (1/Odds_i) / Arb%_decimal
Common Mistakes
Forgetting the draw. In football 1X2 markets, you must cover all three outcomes. Missing the draw means you're exposed to a loss.
Using the same bookmaker for both bets. Both legs must be at different bookmakers, otherwise you're just hedging within one book (which doesn't generate a profit).
Not accounting for fractional odds. If a bookmaker shows 11/10, convert to decimal first: 11/10 + 1 = 2.10.
Ignoring withdrawal fees. Some bookmakers charge fees on withdrawals. Factor this into your effective profit calculation.
Suremargin Does This Automatically
Our platform calculates optimal stake splits in real time. Every opportunity on your dashboard includes exact stake recommendations and the guaranteed profit for your chosen base stake. No manual calculation needed.