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Français The house edge, in plain sight
Bookmakers do not profit by predicting matches better than you; they profit by selling every outcome slightly cheaper than its fair price. Add up the implied probabilities in any market and the total exceeds 100% — that excess is the margin, also called the overround or vig.
A market summing to 105% keeps roughly €5 of every €100 staked across it, regardless of the result. The margin is not hidden anywhere: it is right there in the prices, waiting to be computed.
Calculating it yourself
For each outcome, take 1 ÷ decimal odds; sum the results; subtract 1. A match priced 2.10 / 3.40 / 3.60 gives 0.476 + 0.294 + 0.278 = 1.048 — a 4.8% margin.
Do this once per bookmaker you use and the differences become vivid. In our own research across the leagues we cover, typical best-price margins run around 3%, while single-bookmaker margins on the same fixtures are often 5–7%. Niche markets (correct score, scorers) can carry 10%+ margins — which is exactly why bookmakers advertise them hardest.
What margin costs you over time
A 5% margin means an average bettor loses about €5 per €100 turned over — not per €100 deposited, per €100 staked. Bet €50 twice a week and the margin's expected cost is roughly €260 a year, before any skill or luck enters the picture.
Margin is also the bar your edge must clear: to profit at a 5%-margin bookmaker, your probability estimates must beat the market by more than 5%. Halving the margin you pay — by shopping prices — halves the skill required.
Using margin to choose bookmakers
Margin is one of the fairest single numbers for comparing bookmakers, and one of the least advertised. A generous welcome bonus at a 7%-margin shop is usually worth less over a season than no bonus at a 4%-margin one — the bonus is paid once, the margin is charged on every bet forever.
Our bookmaker margins research page recomputes typical margins from live odds data on every site rebuild, and the calculator below extracts the margin from any market you paste in.
Odds 1.90 / 1.90 on an over-under line: 0.526 + 0.526 = 1.053, a 5.3% margin. The fair price for a genuine coin-flip would be 2.00 / 2.00. At 1.90 you must win 52.6% of such bets just to break even — the 2.6 points between 50% and 52.6% is what the margin charges you.
- Margin = (sum of 1/odds across outcomes) − 1; it is the bookmaker's built-in fee.
- Typical football match-odds margins: ~3% at best price across shops, 5–7% at a single bookmaker.
- Margin scales with turnover — it is charged on every bet, not once.
- Lower-margin bookmakers beat bigger bonuses over any serious time horizon.
Frequently asked questions
Why do margins differ between markets?
Competition and liability. Match odds on big leagues are heavily shopped, so margins compress. Obscure props face no comparison pressure and carry double-digit margins comfortably.
Is a 0% margin possible?
Occasionally a bookmaker prices an outcome above fair as a promotion, and across different bookmakers the best prices on all outcomes sometimes sum below 100% — that is an arbitrage. Both are rare, small and short-lived.
Does margin mean I can't win?
It means the default trajectory is a slow loss at the margin's rate. Winning requires either luck (short term) or probability estimates that beat the market by more than the margin (long term) — a genuine but rare skill.