Sat, 04 Jul 2026

How We Measure Bookmaker Margins

Every price a bookmaker publishes carries a built-in cost. Here's how OddsBash measures it from real published odds, and how the SA betting sites compare.

Every bookmaker builds a cost into the prices it shows you. We call that cost the margin, and here’s the thing: you can measure it straight from the odds sitting right there on their site. No inside information needed, no secret formula.

What a Margin Actually Is

Take every price in a market, convert each to implied probability (that’s 1 ÷ price), and add them up. A home/draw/away market has three prices, so you’re adding three numbers. A perfectly fair market, one with no house edge at all, would land on exactly 100%. Real markets never do. Every betting site’s total sits above 100%, and whatever’s sitting above that 100% is the margin, also called the overround. That’s the built-in cost of betting that market, whichever side you end up backing. Want the fuller walkthrough on implied probability? Read how betting odds work.

Why We Only Count Complete Markets

A margin only means something once every outcome in a market actually has a price. Miss one outcome and the sum understates the real cost, so we just leave that market out of the calculation entirely rather than guess. We’d rather measure fewer markets properly than more markets on shaky numbers. A betting site pricing too few complete markets doesn’t get ranked at all, the sample’s just too thin. See the current cut-off on our methodology page if you want the exact number.

We also average this over time instead of trusting a single snapshot. A betting site’s margin can drift from market to market, hour to hour, so one match on its own barely tells you anything. It’s the average across plenty of matches, over time, that’s actually worth trusting.

What a Margin Costs You

Say one betting site’s market sums to 104%, another’s to 109%. Neither number tells you who’s going to win. What it tells you is how much of your stake ends up with the house over time if you keep betting that market. Spread your bets randomly across enough of them, and a market averaging 4% margin costs you a bit under R4 for every R100 you put down, purely from the pricing. A 9% market costs a bit over R8. Do that all season and the gap adds up, even if your picks are exactly as good either way.

Margin isn’t everything, obviously. Deposit and withdrawal speed, how fast FICA clears, how many markets they actually cover, all of that matters too. It’s just the one number nobody publishes and almost nobody thinks to ask about. So we measure it.

Reading the Best-Value Ranking

Our best-value page ranks licensed South African betting sites by measured average margin, lowest first. Lower means the pricing costs you less, over time. It doesn’t mean that site has the best price on the exact match you’re looking at right now, or the fastest payouts, or the slickest app. For that, check the live odds grid for your match. Treat the ranking as the longer-run signal, not a substitute for comparing today’s actual price.

The full calculation is on the methodology page, and it won’t change without that page changing too.