How to Use an Arbitrage Calculator (With Examples)

An arbitrage calculator turns a set of odds into a precise betting plan. You enter the best odds for each outcome and your total stake; it tells you how much to bet on each side and what profit you'll lock in. Here's how to read every part of it.

What you enter

• Market type — 2-way (two outcomes, e.g. tennis) or 3-way (home/draw/away, e.g. football).
• Odds — the highest decimal odds you found for each outcome, each potentially from a different bookmaker.
• Total stake — how much you want to invest in total across all legs.

The arb index (L)

The calculator first computes L = the sum of 1 ÷ odds for every outcome. This single number tells you everything:

• L < 1.0 → arbitrage exists, you profit.
• L = 1.0 → break-even, no edge.
• L > 1.0 → no arb, you'd lose the bookmaker's margin.

Your profit percentage is (1 ÷ L − 1) × 100. An L of 0.96 means roughly a 4% guaranteed return.

The stake split

For each outcome, the exact stake is: total × (1 ÷ odds) ÷ L. This formula guarantees that whichever outcome wins, the payout is identical — that's what makes the profit certain.

Worked example: 2-way

Odds 2.10 and 2.05, total stake 100.

L = 0.4762 + 0.4878 = 0.964 → about +3.7%.
Stake on side 1: 100 × 0.4762 ÷ 0.964 ≈ 49.4
Stake on side 2: 100 × 0.4878 ÷ 0.964 ≈ 50.6

If side 1 wins: 49.4 × 2.10 ≈ 103.7. If side 2 wins: 50.6 × 2.05 ≈ 103.7. Either way you get back ~103.7 on a 100 stake — a ~3.7 profit.

Worked example: 3-way

Football odds 2.45 (home), 3.40 (draw), 3.10 (away), total 100.

L = 0.408 + 0.294 + 0.323 = 1.025 → L is above 1.0, so this is not an arb. The calculator would show a small expected loss. This is normal — most real markets are not arbs, which is exactly why a calculator is useful: it tells you instantly whether to skip.

Why rounding matters

The exact stakes (like 49.4) are rarely clean. Bookmakers may flag oddly precise amounts, so the calculator also shows rounded whole-number stakes. Rounding slightly changes each payout, so a good calculator recalculates the real profit on the rounded numbers — and warns you if rounding turns a thin arb negative.

Use it before every bet

Even experienced arbers run every opportunity through a calculator. It takes seconds, removes mental-math errors, and confirms the margin survives rounding before any money is placed. Treat it as a mandatory final check, not an optional tool.

Enter your odds and get the exact stake split in seconds.