Betting analytics glossary
Devigging odds, explained cleanly
Devigging strips the bookmaker’s margin out of a set of odds to reveal the underlying implied probability. It’s the small, unglamorous step that separates real positive-EV analysis from wishful thinking.
TL;DR
- Bookmaker odds always include a margin (vig, juice, or overround). The implied probabilities on a market sum to more than 100%; the excess is the vig.
- Devig by dividing each implied probability by the sum. Two sides both at 1.91 sum to 104.7% implied; divide each by 1.047 to get a clean 50% each.
- Sharp-market devigged prices are the reference for +EV work.Skipping the devig step systematically overstates the sharp market’s implied probability.
- Multiplicative devig is fine for most cases. Power methods (Shin, logistic) matter more when the market is heavily lopsided but the difference is usually under 1 percentage point on liquid balanced markets.
Vig, juice, overround — same thing
Bookmakers make money by pricing their odds so the implied probabilities sum to more than 100%. On a coin-flip market (two outcomes at 50/50 true probability), a “fair” price would be 2.00 on each side (each implying 50%). A bookmaker instead offers 1.91 on each, which implies 52.4% per side. Sum: 104.7%. The 4.7% overage is the vig — the bookmaker’s expected long-run profit per unit staked, assuming their prices are correct.
Vig is why you can’t just take raw bookmaker odds as true probability. Sharp books like Pinnacle run ~2-3% vig on major markets. Soft books often run 5-10%+, sometimes far more on obscure props.
The formula (multiplicative devig)
For any set of mutually exclusive outcomes:
No-vig prob(i) = (1 / odds(i)) ÷ Σ(1 / odds(j))In words: compute each outcome’s implied probability (1 / decimal odds), sum them across all outcomes, then divide each outcome’s implied probability by the sum. The resulting probabilities sum to exactly 100%.
Worked example: two-way market
Match odds on a tennis match, Pinnacle: Player A 1.91, Player B 1.91.
- Implied A: 1 / 1.91 = 0.524 (52.4%)
- Implied B: 1 / 1.91 = 0.524 (52.4%)
- Sum: 1.047 (104.7%) — vig is 4.7%
- No-vig A: 0.524 / 1.047 = 0.500 (50.0%)
- No-vig B: 0.524 / 1.047 = 0.500 (50.0%)
The devigged probabilities give a clean, sums-to-100% estimate of the market’s view of true odds. That’s what you compare your soft-book price against for +EV analysis.
Worked example: three-way market (soccer 1X2)
Premier League match, Pinnacle: Home 2.10, Draw 3.40, Away 3.60.
- Implied Home: 1 / 2.10 = 0.476 (47.6%)
- Implied Draw: 1 / 3.40 = 0.294 (29.4%)
- Implied Away: 1 / 3.60 = 0.278 (27.8%)
- Sum: 1.048 (104.8%) — vig is 4.8%
- No-vig Home: 0.476 / 1.048 = 0.454 (45.4%)
- No-vig Draw: 0.294 / 1.048 = 0.281 (28.1%)
- No-vig Away: 0.278 / 1.048 = 0.265 (26.5%)
These three sum to exactly 100%. Now say your soft bookmaker has the Home at 2.30 (43.5% implied). Sharp devigged says 45.4%; you’re getting 43.5%. Positive gap in your favour of 1.9 percentage points — that’s a +EV bet worth taking, sized appropriately.
Multiplicative vs power devig
Multiplicative devig (above) assumes the bookmaker distributes their vig proportionally across outcomes. In practice, this is not quite true — bookmakers often pad the longshot side more heavily than the favourite. Power methods (Shin, logistic) try to correct for this by weighting the devig based on the structure of the odds.
The practical difference on liquid balanced markets is usually under 1 percentage point. On heavily lopsided markets (big favourite / big longshot), the difference can be larger. For most retail +EV workflows, multiplicative is perfectly serviceable and much easier to compute by hand. Serious sharp operations use power methods, especially on props and futures.
Where devigging fits in the workflow
The full sharp-book +EV loop:
- Pick a sharp-market reference — Pinnacle, Betfair Exchange, or Circa depending on jurisdiction and market.
- Devig the sharp priceto get the no-vig implied probability. This is the “true” probability for the purposes of your EV calculation.
- Compare against your soft-book price. If the soft book implies a lower probability than the sharp devig implies, and by a material amount, you have a +EV bet.
- Size according to Kelly (usually half or quarter Kelly) given your edge and bankroll.
- Track CLV after the fact. If your entry prices consistently beat the closing line, your +EV estimates are working.
Skip the devig step and every downstream number is wrong. That’s why every serious +EV tool devigs by default.
Related terms
Frequently asked questions
What is devigging in sports betting?
Devigging is the process of stripping the bookmaker's built-in margin (called vig, juice, or overround) out of a set of odds to estimate the true implied probability of each outcome. It matters because bookmaker prices always include a profit margin that inflates the implied probabilities above 100%. Removing that margin gives you a cleaner estimate of the market's view of true odds.
What is vig (juice, overround) in sports betting?
Vig, juice, and overround are the same thing: the bookmaker's margin baked into the odds. On a two-way market where each side is priced at 1.91, the implied probabilities sum to 104.7% — that extra 4.7% is the vig. It's the bookmaker's expected long-run profit per unit of stake. Sharp books like Pinnacle run at roughly 2-3% overround; soft recreational books often run 5-10% or more.
How do you devig two-way odds?
The simplest method (multiplicative devig): compute implied probability for each side (1/odds), sum them (this is >100% because of vig), then divide each side's implied probability by the sum. Example: two sides at 1.91 each imply 52.4% each, summing to 104.7%. Devig: 52.4 / 104.7 = 50%. Each side's no-vig implied probability is 50%.
How do you devig three-way odds (like soccer 1X2)?
Same principle: compute implied probability for each of the three outcomes (1 / odds), sum them (again >100% due to vig), then divide each by the sum. Example: home 2.10, draw 3.40, away 3.60. Implied: 47.6% + 29.4% + 27.8% = 104.8%. Devig home: 47.6 / 104.8 = 45.4%. Do the same for draw and away and the three no-vig probabilities sum to exactly 100%.
Why do sharp bettors devig?
Because the whole point of positive EV betting is comparing your bookmaker's price to a true reference probability. The raw sharp-market price is not the true probability — it includes vig. To get an honest reference, you have to strip the vig out. Skipping this step systematically overstates the sharp market's implied probability, which makes you think bets are +EV when they are not.
What is the best devig method?
Two main methods. Multiplicative (proportional): divide each implied probability by the sum. Simple, works well for balanced markets. Power (Shin, logistic): accounts for the fact that vig is often not distributed proportionally — bookmakers pad the favourite less and the longshot more. Power methods are more accurate on markets with a heavy favourite or a longshot, but the difference is usually small (<1 percentage point) on liquid balanced markets. For most bettors, multiplicative is a good default.