Value betting, what it is and how simplyodds finds it
A value bet is a price longer than the true probability of the outcome. Find enough of them and you win long-term, regardless of which individual bets lose.
The one-paragraph version
Bookmakers don't need to predict the result. They set a price that, after their margin, returns them money on average. A value bet is one where the price they offer is longer (= a higher decimal number) than the true probability of the outcome happening. If a fair coin paid 2.10 instead of 2.00, every flip is a value bet, even though half the time you lose.
Why prices differ between books
Bookmakers are not all betting against the same model. A book optimised for Asian volume prices a Premier League match differently to a UK retail book. Crypto books move slower than sharp ones on player props. Polymarket, being a peer-to-peer prediction market, has no margin in the mid-price at all. Compare prices across 10 books and the spread is normally 3-8% on top-league football, and wider in second-tier leagues and side markets.
The simplyodds method
For every match we take the Polymarket mid-price as our fair line, there's no bookmaker margin baked in, so it's as close to the market's true belief as you can get. We then compare what the 10 books are paying. When a book offers a price longer than the fair line, that's an edge. The bigger the gap, the bigger the edge.
What value betting is not
It isn't tipping. We don't predict who will win. We surface a mispricing, a price the market has wrong, and let you decide whether to take it. Over a single match, value bets lose plenty. Over 200, the maths shows up.
Bankroll: the second half of the job
Finding a value bet is the easy bit. Sizing the stake so a bad run doesn't bust you is what separates a sustainable approach from a hobby. We recommend quarter Kelly, bet 25% of the Kelly-optimal stake, as a sensible compromise between growth and survival. The Kelly calculator does the maths.
FAQ
- Is value betting legal?
- Yes. You're placing legal bets on regulated and licensed bookmakers. What books don't like is winning customers, they may limit your account, but that's a commercial decision, not a legal one.
- How big does the edge need to be?
- For an individual bet to be worth taking, anything over a 2% edge after factoring in real-world friction (limits, exchange rates, fees) is meaningful. We surface edges of 3%+ by default, below that the noise drowns the signal.
- How long until value betting "works"?
- Expect at least 200 bets before your results stabilise around expected value. Anything below that is noise.