How betting odds work
South African bookmakers show decimal odds: multiply your stake by the odds to get your total return, so R100 at 2.50 returns R250, including your R100 stake. Divide 1 by the odds to get the implied probability (2.50 means 40%), and add up a market's probabilities to see the bookmaker's margin.
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Odds tell you two things at once: how much you’ll be paid if a bet wins, and how likely the bookmaker thinks it is to win. Once you can read both, you can compare bookmakers properly and spot when a price is poor. This guide uses the decimal odds every South African betting site shows.
Decimal odds: the basics
Total return = stake × odds Profit = total return − stake
| Odds | R100 stake returns | Profit | Implied probability |
|---|---|---|---|
| 1.25 | R125 | R25 | 80% |
| 1.50 | R150 | R50 | 67% |
| 2.00 (evens) | R200 | R100 | 50% |
| 2.50 | R250 | R150 | 40% |
| 3.40 | R340 | R240 | 29% |
| 5.00 | R500 | R400 | 20% |
| 11.00 | R1,100 | R1,000 | 9% |
Decimal odds always include your stake. That’s why odds of 1.01 still return slightly more than you bet, and why odds can never be below 1.
Implied probability
Implied probability = 1 ÷ decimal odds
If Mamelodi Sundowns are 1.50 to win, the price implies a 67% chance. If you think they win more often than that, the price looks good to you; if less, it doesn’t. This is the core of judging value: you’re comparing your own estimate with the bookmaker’s.
Fractional and American odds
You’ll mostly see decimals on SA betting sites, but fractional odds still appear in horse racing and in older guides.
- Fractional: 5/2 means R5 profit for every R2 staked. To convert, divide and add 1: 5 ÷ 2 + 1 = 3.50.
- American: +250 means R250 profit on a R100 stake (decimal 3.50); −200 means you stake R200 to win R100 (decimal 1.50).
Our odds converter switches between all three and shows the implied probability.
The bookmaker’s margin
Bookmakers don’t offer fair odds. They shade every price a little, so that the implied probabilities in a market add up to more than 100%. The excess is their margin (also called the overround or vig).
Here’s a typical PSL match result market:
| Outcome | Odds | Implied probability |
|---|---|---|
| Home win | 2.10 | 47.6% |
| Draw | 3.10 | 32.3% |
| Away win | 3.60 | 27.8% |
| Total | 107.7% |
The total is 107.7%, so the margin is roughly 7%. Remove it and the fair odds would be about 2.26, 3.34 and 3.88. Every bet you place in that market pays a little less than it should, which is how bookmakers earn over time, just like the house edge in a casino.
Margins vary a lot:
- Big football matches (EPL, Champions League): often 3% to 6%.
- PSL and smaller leagues: often 6% to 10%.
- Player props, correct score and specials: often much higher.
- Accumulators: the margin compounds with every leg (see below).
Comparing the same market across bookmakers is the easiest way to get better value. Our compare page puts bookmakers side by side, and these are the top-rated betting sites in our data:
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Accumulators
An accumulator (acca or multibet) combines several selections into one bet. All must win, and the odds multiply:
Combined odds = odds of leg 1 × odds of leg 2 × odds of leg 3 …
Three legs at 1.80, 1.65 and 2.20 give 1.80 × 1.65 × 2.20 = 6.53. A R20 acca returns about R130.
The big returns come with two costs. First, the chance of all legs winning falls fast: if those legs really had 55%, 60% and 45% chances, the acca wins about 15% of the time. Second, each leg carries its own margin, so a 7% margin per leg becomes roughly 20% on a three-leg acca and far more on ten legs. That’s why bookmakers love accas and offer acca boosts, insurance and Hollywoodbets-style “money back” deals on them.
Our bet calculator works out the returns on singles, accas and system bets.
Common market types and their odds
- 1X2 (match result): home, draw or away. The draw is often the longest price in an even match.
- Double chance: two of the three outcomes (1X, X2 or 12). Shorter odds, fewer losing results.
- Draw no bet: your stake comes back if the match is drawn.
- Over/under goals: for example over 2.5 goals. PSL matches are often low scoring, so “under” prices are shorter than in many European leagues.
- Both teams to score (BTTS): yes or no.
- Handicaps: one team starts with a goal or point deficit to even the market.
See how these apply in our PSL betting guide.
How odds move
Odds change as the bookmaker takes bets and as news comes in: a key player injured, a change of coach, the weather at a cricket ground. If lots of money comes in on one side, its price shortens and the other side drifts. Live betting odds move second by second as the game unfolds, and the margin on live markets is usually higher. A cash-out offer is simply the bookmaker pricing your open bet at the current odds, with a margin.
Odds on other sports and bet types
The same maths applies everywhere, but each sport has its quirks.
- Rugby and cricket: draws are rare (in rugby) or common (in Test cricket), which changes how two-way and three-way markets are priced. Springboks and Proteas matches draw heavy local interest, so prices can shorten on the home side.
- Horse racing: SA racing offers both fixed odds from bookmakers and tote betting, where all the money in a pool is shared among winners after a deduction. Tote dividends aren’t known until the race is run. Fixed odds lock in your price when you bet.
- Lucky Numbers: bookmakers offer fixed odds on lottery-style draws, for example picking one number correctly. These odds are set well below the true chance, so the margin is large.
- Live betting: odds update constantly, and suspended markets during big moments (a penalty, a wicket) are normal.
Value betting, explained honestly
A “value bet” is one where the odds are longer than the true chance of the outcome. If you think a team wins 50% of the time and the bookmaker offers 2.30 (an implied 43%), that’s value by your estimate. Over many bets, only value bets can be profitable.
The hard part is the estimate. Bookmakers employ traders and models, and their prices are usually close to right before the margin. Most bettors who think they’ve found value haven’t. Use the idea to avoid obviously poor prices, not as a promise of profit, and keep stakes small enough that being wrong doesn’t hurt.
Odds and free bets
When you use a free bet, the stake usually isn’t returned. A R50 free bet at 3.00 pays R100, not R150. That’s why free bets are worth more at higher odds, and why bookmakers set minimum odds on them. Read our guide to wagering requirements for how betting bonus terms work.
Quick reference
- Return: stake × odds.
- Profit: return − stake.
- Implied probability: 1 ÷ odds.
- Fractional to decimal: (a ÷ b) + 1.
- Margin: sum of 1 ÷ odds across a market, minus 100%.
- Acca odds: multiply all legs.
Bet with a plan
Understanding odds helps you make better-informed bets, but it doesn’t remove the margin. Decide your stake before you bet, never chase losses, and use your account’s deposit limits. If betting stops being fun, call the National Responsible Gambling Programme on 0800 006 008.
Frequently asked questions
How do betting odds work in South Africa?
SA bookmakers use decimal odds. Your total return is your stake times the odds, and your profit is that return minus the stake. R50 on odds of 3.00 returns R150, which is R100 profit plus your R50 back.
What does odds of 1.50 mean?
It means a R100 bet returns R150 if it wins: R50 profit plus your stake. The implied probability is 1 ÷ 1.50, or about 67%.
How do I convert fractional odds to decimal?
Divide the first number by the second and add 1. Odds of 5/2 become 2.5 + 1 = 3.50, and 1/4 becomes 0.25 + 1 = 1.25. Our odds converter does it for you.
What is the bookmaker's margin?
It's the bookmaker's built-in edge. Add up 1 ÷ odds for every outcome in a market: if the total is 107%, the margin is about 7%. Lower margins mean better value for you.
How are accumulator odds calculated?
Multiply the odds of every leg. Three legs at 1.80, 1.65 and 2.20 give combined odds of about 6.53, so R20 would return about R130.68 if all three win.
What does 'odds on' mean?
Odds on means the decimal odds are below 2.00, so the bookmaker thinks the outcome is more likely than not. Odds of 2.00 are 'evens'.
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Mark has been writing about online gaming since 2007, covering everything from sportsbooks to casino and slot reviews, offering insights for players of all levels.