Bookmaker margin: how to calculate it and what Latvian sportsbooks charge

The bookmaker margin (overround) is how far the implied probabilities of all outcomes add up past 100%. The formula: margin = (1 / o1 + 1 / o2 + 1 / o3) - 1. On Liverpool - Brighton, Optibet's odds of 2.10 / 3.80 / 3.20 (24.10.2026) add up to 1.0518, so a margin of 5.18% and a payout percentage of 95.07%. The same match cost between 4.02% and 5.20% in margin across six sportsbooks. Every bet type is collected on our sportsbooks page, and this lesson is part of our betting academy.

How the margin is calculated

You calculate the margin by adding up the implied probabilities of all outcomes and subtracting 100%.

Implied probability is one divided by the odds. We explained how it works in our beginners' guide, so here is just the calculation step by step on the Liverpool - Brighton example (Optibet, 24.10.2026):

• Liverpool win, 2.10: 1 / 2.10 = 0.4762
• Draw, 3.80: 1 / 3.80 = 0.2632
• Brighton win, 3.20: 1 / 3.20 = 0.3125
• Total: 1.0518, so a margin of 5.18%

In a fair market the total would be exactly 1.0000. Everything above that is the bookmaker's cut. The other number you will often see is the payout percentage: 1 / 1.0518 = 95.07%. It means that of every 100 euros staked across all outcomes in matching proportions, the bookmaker pays back 95.07 euros on average. Margin and payout percentage are two ways of writing the same fact, and every percentage in this article says which one it is.

In a two-way market the calculation is the same. If both outcomes are priced at 1.90, the total is 1 / 1.90 + 1 / 1.90 = 1.0526, a margin of 5.26% and a payout percentage of 95.0%.

Odds formats

Latvian sportsbooks show decimal odds, but foreign sites also use fractional and American formats.

• Fractional 5/2: you win 5 for every 2 staked, plus your stake back, so the decimal odds are 5 / 2 + 1 = 3.50.
• American +150: you win 150 for every 100 staked, so 150 / 100 + 1 = 2.50.
• American -200: you stake 200 to win 100, so 100 / 200 + 1 = 1.50.

The margin formula only works with decimal odds, so convert other formats first.

Fair odds: which outcomes pay most of the margin

The bookmaker's cut is not spread evenly - in one-sided matches bets on the outsider and the draw pay most of it.

The simplest method works out fair odds proportionally: each outcome's implied probability is divided by the total. It assumes the margin is the same on every outcome. TonyBet gives a better view, because its public odds feed also shows the bookmaker's own probabilities with the margin removed.

On the Champions League match Barcelona - Aston Villa (24.10.2026) TonyBet offered 1.23 / 6.80 / 9.00. The same bookmaker's no-margin probabilities correspond to fair odds of 1.283 / 7.954 / 10.562. So the offered price was 95.9% / 85.5% / 85.2% of fair: about 4% was trimmed from the favourite and about 15% from the draw and the outsider. In all 18 Champions League matches we read, the favourite was the outcome trimmed least. The proportional method would miss that difference entirely.

Balanced matches look different. In the Premier League on the same evening TonyBet's cut across five matches was almost even - favourites averaged 94.72% of the fair price, the other outcomes 95.28%. On Liverpool - Brighton it was actually the favourite that was trimmed most (92.8% of the fair price against 97.1% and 96.9%).

What Latvian sportsbooks charge

In our 24.10.2026 measurement no sportsbook was cheapest in every sport - the cheapest in football was expensive in hockey, and the other way round.

SpinsPilot measurement, 24.10.2026, 18:10-18:32 UTC: 31 matches, each match's odds read at every sportsbook within a few minutes, main market only. In football that is 1X2, in hockey 1X2 in regulation time, in basketball the winner including overtime. The figure is the average margin, with the range in brackets. Optibet, Laimz and Klondaika use one odds feed, so they share one row. OlyBet is included as a market reference point.

Football (10 matches: 5 Premier League, 5 Champions League), more on our football betting page:

• LVBet: 4.06% (3.59-4.39%)
• Betsafe: 4.37% (3.38-5.40%)
• OlyBet: 4.60% (3.89-5.20%)
• GG.BET: 4.69% (4.05-5.35%)
• Optibet / Laimz / Klondaika: 5.76% (5.03-6.45%)
• TonyBet: 6.10% (4.70-7.37%)

Hockey (4 NHL and 6 KHL matches; Betsafe and GG.BET do not offer the KHL, so NHL only for them), more on our hockey betting page:

• TonyBet: 4.55% (3.78-6.27%)
• GG.BET (NHL only): 5.22% (5.18-5.28%)
• Betsafe (NHL only): 5.32% (4.46-6.11%)
• OlyBet: 6.61% (5.75-7.16%)
• LVBet: 7.57% (7.02-7.92%)
• Optibet / Laimz / Klondaika: 8.00% (7.63-8.33%)

On the four NHL matches alone, where all six can be compared: TonyBet 4.00%, GG.BET 5.22%, Betsafe 5.32%, OlyBet 5.93%, LVBet 7.55%, Optibet feed 8.07%.

Basketball (5 NBA and 6 EuroLeague matches), more on our basketball betting page:

• Optibet / Laimz / Klondaika: 5.14% (4.28-6.03%)
• LVBet: 5.41% (5.06-5.97%)
• GG.BET: 5.50% (5.06-6.03%)
• TonyBet: 5.52% (3.74-6.97%)
• Betsafe: 5.75% (5.25-7.21%)
• OlyBet: 7.77% (5.07-9.96%)

The gaps between leagues are even wider. TonyBet charged 5.10% on the Premier League but 7.11% on the Champions League; on the NBA it was the cheapest (3.90%), on the EuroLeague 6.87%. OlyBet's margin on EuroLeague matches was 9.81-9.96%. GG.BET's EuroLeague odds matched the Optibet feed on all six matches.

This is a one-evening measurement, not a rating. Margins move by league, market and day: TonyBet's average Premier League margin was 7.03% in our 28.09.2026 pilot measurement and 5.10% on 24.10.2026. We will repeat the measurement every quarter.

Where the margin hides

Side markets, special features and accumulators often carry a higher margin than the main market.

At the Optibet feed the "over/under 2.5 goals" market cost more than 1X2 on all five Premier League matches: 7.72% against 5.77% on average. On Liverpool - Brighton the 1X2 margin was 5.18%, while over/under 2.5 (1.52 / 2.37) was 7.98%. TonyBet showed no such gap that evening (5.07% against 5.17%), which is why it is "often" and not "always". In an accumulator the margin builds up with every leg - exactly how much is shown in the table in our article on single, accumulator and system bets.

What this margin costs when you wager a sports bonus, and why accumulators make it more expensive, is shown in euros in Sports bonus wagering: what a betting bonus is really worth in euros.

Comparing odds

Taking the best price for each outcome across sportsbooks cuts the margin more than picking any single sportsbook.

On Liverpool - Brighton the six sportsbooks charged between 4.02% and 5.20%. Taking the best price for each outcome from all six (2.14 / 3.98 / 3.30) would bring the margin down to 2.16%. Across all our football matches this cut the margin to 1.30-2.84%. That is an argument for comparing prices if you already hold more than one account. It is not worth opening new accounts for this reason.

On "arbitrage bets", where all outcomes are combined so that the total comes out positive, one sentence: they rarely stay safe. Prices move while you place the second bet, sportsbooks can settle obviously wrong prices at odds of 1.00 (Optibet's terms, 4.5.4) and can change customer limits (2.4.5.3).

If you compare prices among Latvian-licensed sportsbooks, the lowest average football margin in our measurement was at LVBet, and on Champions League matches at Betsafe (3.53%). In hockey and basketball the order was different.

Previous lesson: 1X2, double chance and regulation time.

How to use fair odds to judge whether a bet has value, and why that is harder than it sounds, is covered in the next lesson, Value bets and the Kelly criterion: the honest maths.

Play within your means

The margin means the bookmaker is always ahead in the long run, and no amount of price comparison changes that. Set a budget before you start and stop when it is spent. Our responsible gambling page collects the tools that help, and you can add yourself to the State Revenue Service's self-exclusion register at any time. The Centre for Disease Prevention and Control runs an anonymous addiction helpline on 67037333. Betting is for people aged 18 and over.