Quick answer
Sure bet: “Sure bet” is industry slang for an arbitrage position: the combination of best prices across bookmakers whose implied probabilities sum to less than 100%.
Also called: arb, risk-free bet (misleading)
Explained, with an example
The name overstates it. The return is only locked in if every leg is placed at the quoted price and every bookmaker honours the bet; prices move within seconds, stakes can be capped (Odds-API.io returns maxStake where known) and void rules differ between operators [1] [2]. Treat “sure” as “calculated at the quoted prices”, not guaranteed.
Try it: tools and tutorials
Frequently asked questions
What is a sure bet?
“Sure bet” is industry slang for an arbitrage position: the combination of best prices across bookmakers whose implied probabilities sum to less than 100%.
About this guide
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Author: Ken Lin · Corrections: if you spot an error, we review it and date-stamp the fix.
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Sources
- Arbitrage Bets guide (formula, response format, limitations) — Odds-API.io docs, accessed 2 Nov 2026
- What Is Arbitrage Betting? Definition & Example — Odds-API.io glossary, accessed 2 Nov 2026