Sure Bet (Arbitrage) Calculator
Enter your total stake and the odds for each possible outcome. Use decimal odds by default (you can also enter American like +120 / -110 or fractional like 11/10).
A sure bet calculator helps you distribute stakes across all outcomes of an event so that your return is as even as possible. When the combined implied probability is below 100%, you have an arbitrage opportunity (often called a “sure bet”), which means a guaranteed profit before fees and limits.
What is a sure bet?
A sure bet happens when odds from different sportsbooks create a pricing mismatch. If you back every outcome at those prices, one outcome must win, and your payout can exceed your total stake.
- Implied probability: For decimal odds, it is
1 / odds. - Arbitrage condition: Sum of all implied probabilities is less than 1 (or less than 100%).
- Guaranteed edge: Profit exists only if that sum is below 100% after considering commissions and transaction costs.
How to use this calculator
- Set your total stake (how much money you want to risk in total).
- Select the number of outcomes for the market (2-way, 3-way, etc.).
- Enter odds for each outcome from different books.
- Click Calculate Sure Bet.
- Review recommended stake per outcome, expected payout, and ROI.
The math behind stake distribution
Step 1: Add implied probabilities
If your decimal odds are o1, o2, ... on, compute:
S = (1/o1) + (1/o2) + ... + (1/on)
If S < 1, a sure bet exists. If S = 1, you break even before costs. If S > 1, no arbitrage.
Step 2: Split your bankroll
For total stake T, each stake is:
stake_i = T * ((1/oi) / S)
This makes the payout across outcomes approximately equal.
Step 3: Compute return and profit
Expected payout per outcome is approximately:
payout = T / S
Profit is:
profit = payout - T
Practical tips for finding better arbitrage spots
- Compare multiple sportsbooks quickly; stale lines disappear fast.
- Prefer liquid markets where stake limits are higher.
- Check rules consistency (overtime included? draw no bet? void conditions?).
- Account for commissions, currency conversion, and withdrawal costs.
- Keep a margin buffer; tiny arbs can vanish with one odds update.
Common mistakes
Ignoring market rules
Two books may quote similar-looking odds but grade markets differently. A mismatch in rules can destroy the hedge.
Rounding too aggressively
Small rounding errors can convert a thin profit into a loss. Place exact stake amounts where possible.
Forgetting account limits
If one leg gets restricted and you cannot place the other side, your strategy turns into a directional bet.
FAQ
Can I use this for 3-way soccer markets?
Yes. Set outcomes to 3 and enter odds for Home/Draw/Away.
Does this work with American odds?
Yes. You can type values such as +120 or -110; the calculator converts them internally to decimal odds.
What ROI is considered good?
Most true arbitrage opportunities are small (often under a few percent). Consistency and execution quality matter more than one-off big numbers.
Final thoughts
A sure bet calculator is a precision tool. It does not “create” value by itself, but it helps you act on pricing inefficiencies with disciplined stake sizing. Use it to validate opportunities quickly, reduce human error, and make clearer, data-driven decisions.