How Betting Odds Work
Betting odds do two jobs at once: they tell you the payout on a winning stake, and they encode the bookmaker's estimated probability of an outcome. In South Africa, odds are almost always shown in decimal format — 2.50, 1.65, 4.00 — so a R100 stake at 2.50 returns R250 (your R100 back plus R150 profit). The number you don't see printed anywhere is the margin the bookmaker builds into those prices. Across a 238-selection sample, Betway held the best available price 90.8% of the time at an average margin of 6.49%, while 10bet averaged a tighter 4.78% margin over 27 selections. Understanding how that margin works is the difference between a fair price and an overpriced one.
Decimal odds and what a price actually pays
Decimal odds represent the total return per R1 staked, inclusive of your stake. The formula is simple:
- Return = Stake × Decimal odds
- Profit = Stake × (Decimal odds − 1)
At 1.80, a R200 stake returns R360 (R160 profit). At 3.20, that same R200 returns R640 (R440 profit). Odds below 2.00 mean the outcome is judged more likely than not — you risk more than you stand to win in profit terms. Odds above 2.00 are the reverse.
South African books like Betway, Hollywoodbets and Supabets display decimal odds by default, which makes payout maths quick: no fractional conversions, no plus/minus American lines. This is the format used throughout this guide.
Implied probability: reading the number behind the price
Every decimal price converts directly into an implied probability:
- Implied probability = 1 ÷ decimal odds
A price of 2.00 implies 50% (1 ÷ 2.00). A price of 1.50 implies 66.7%. A price of 5.00 implies 20%. This is the bookmaker's assessment of how often the outcome should occur — adjusted for their margin.
This single calculation is the most useful skill for a bettor. If you believe Mamelodi Sundowns should win a PSL fixture around 60% of the time, the fair price is 1 ÷ 0.60 = 1.67. If a book is offering 1.85 on that outcome (implied 54.1%), the price is in your favour. If it's offering 1.50 (implied 66.7%), you're being asked to accept worse-than-fair odds.
Odds Converter
The bookmaker margin — why the probabilities add up to more than 100%
In a fair, margin-free market the implied probabilities of all outcomes would sum to exactly 100%. They never do. The excess is the bookmaker's margin (also called the overround or vig), and it is how the book builds in profit.
Take a two-way market — say a tennis match on the ATP Tour priced 1.90 / 1.90:
- Player A implied: 1 ÷ 1.90 = 52.63%
- Player B implied: 1 ÷ 1.90 = 52.63%
- Total: 105.26%
The 5.26% above 100% is the margin. The tighter that number, the more value stays with the bettor. In BETAXIO's sampling, 10bet averaged a 4.78% margin, Betway 6.49% and Sportingbet 8.63% — meaning that, on average, Sportingbet extracted roughly 1.8× the margin 10bet did on comparable selections.
Worked example: comparing two prices on the same match
Consider a Premier League match where the home win is offered at two prices:
- Book X: 2.10 → implied 47.62%
- Book Y: 2.30 → implied 43.48%
On a R500 stake:
- Book X returns R1,050 (R550 profit)
- Book Y returns R1,150 (R650 profit)
Same bet, same outcome, R100 more profit simply for taking the better price. Over a season of 200 such bets, consistently taking the higher price is worth thousands of rand — with no change to how well you actually predict.
This is why best-price share matters. In the sampled data, Betway offered the top available price on 90.8% of 238 selections, and 10bet on 85.2% of 27. Sportingbet led on only 28.2% of its 39 sampled selections. If you only ever bet at one book, the best-price share tells you how often you're leaving money on the table.
Margin, best-price share and how they rank operators
Two metrics drive price quality in the BETAXIO data:
- **Average margin** — how much overround is baked into prices. Lower is better for the bettor.
- **Best-price share** — how often that operator holds the highest available price across sampled selections.
On margin, the sampled ranking is:
- 10bet — 4.78% (27 selections)
- Betway — 6.49% (238 selections)
- Sportingbet — 8.63% (39 selections)
On best-price share:
- Betway — 90.8%
- 10bet — 85.2%
- Sportingbet — 28.2%
Note the sample sizes differ substantially: Betway's figures rest on 238 selections, 10bet's on 27. A tighter average margin from a smaller sample carries more uncertainty. Operators without odds_metrics in the dataset — Hollywoodbets, Supabets, Sunbet, World Sports Betting, BetXchange, LulaBet, Easybets — are not price-ranked here because no sampled margin data is available for them. Their editorial ratings (Betway odds 7.9, Sportingbet 7.6, 10bet 7.5, World Sports Betting 7.1, Sunbet 7.0) reflect a broader assessment, not the sampled margin figures above.
Odds move — and why the line changes
The price you see is not fixed. Odds shift between the opening line and kick-off as money comes in and as new information arrives — a confirmed injury, a change in expected conditions, or heavy stakes on one side. When a large share of money lands on the favourite, the book shortens that price (odds fall) and lengthens the other side to balance the book.
For the bettor, this creates two practical points. First, the opening line is often the least efficient — it reflects the book's model before the market has weighed in. Second, tracking how a price has moved tells you where the money is going. Our market movers tool tracks these shifts, and the odds pages show live prices across operators so you can compare rather than accept the first number you see.
Cash Out, Bet Builder and how odds apply live
In live (in-play) betting, prices update continuously as the match state changes — a goal, a red card, or a wicket instantly repriced. Every operator in this list offers Live Betting.
Cash Out lets you settle a bet before the event ends, at a value derived from the current live odds versus your original price. Betway, Sportingbet and 10bet list Cash Out among their features; Hollywoodbets, Supabets, Sunbet, World Sports Betting, BetXchange, LulaBet and Easybets do not list it.
Bet Builder combines several selections within one match into a single price. Betway lists Bet Builder among its features. Combined-selection prices multiply the individual decimal odds, and margin compounds across each leg — so a four-leg builder carries considerably more overround than a single. That's the trade-off for the convenience of one ticket.
Legal context for odds in South Africa
Betting in South Africa is regulated at provincial level under the National Gambling Board framework, with each operator licensed by a provincial authority. In this list, Betway, Sportingbet, Sunbet, LulaBet and 10bet are licensed by the Western Cape Gambling & Racing Board; Hollywoodbets by the KZN Gaming & Betting Board; Supabets, World Sports Betting and BetXchange by the Gauteng Gambling Board; and Easybets by the Mpumalanga Economic Regulator. The minimum betting age is 18.
All operators covered here are licensed. Deposits start from R10 at most (Easybets lists R5), typically via Instant EFT, Ozow, 1Voucher, Capitec Pay or Visa. Withdrawal windows range from 0–24h at several books to 24–72h at Hollywoodbets and Supabets. See legal betting sites South Africa for the full licensing picture.
FAQ
How do I convert decimal odds to a probability?
Divide 1 by the decimal odds. A price of 2.50 implies a 40% chance (1 ÷ 2.50). A price of 1.40 implies 71.4%. This gives you the bookmaker's estimated probability, inflated slightly by their margin.
What does a bookmaker margin of 6% actually cost me?
It means the implied probabilities across a market sum to roughly 106% instead of a fair 100%. That 6% excess is the book's built-in edge. On a two-way market priced fairly, lower margin leaves more of the value with you — which is why 10bet's sampled 4.78% average is more favourable than Sportingbet's 8.63%.
Why are the odds different at each bookmaker for the same match?
Each book prices independently using its own model, its own margin and its own exposure. On the sampled data, Betway held the highest available price 90.8% of the time. Comparing prices before you bet — rather than accepting the first one — is the single easiest way to improve returns without improving your predictions.
Does decimal odds include my stake in the payout?
Yes. Decimal odds show the total return per R1 staked, including your stake. At 3.00, a R100 bet returns R300 total — your R100 plus R200 profit. To find profit only, multiply your stake by (odds − 1).
What is 'best-price share'?
It's how often an operator holds the highest available price across a sample of selections. Betway's best-price share was 90.8% over 238 selections and 10bet's was 85.2% over 27. A higher share means you leave less money on the table by betting there.
Why do odds move before kick-off?
Prices adjust as money arrives and as new information (injuries, line-ups, conditions) emerges. Heavy backing on one side shortens that price and lengthens the other so the book stays balanced. The opening line is usually the least efficient, before the market has weighed in.