Tool · Sports Betting · Conversion

Odds
converter.

Convert between decimal, fractional and American odds and see the implied probability for any price. Decimal odds, the format SA bookmakers use, are the default.

Calculator

Convert any odds format

Type into any field and the others update automatically.

Enter odds in any format to see conversions

How to use this tool

Type the odds into whichever format you have them in, and the converter works out the other two as you type. The implied probability at the top is the chance of this outcome that the bookmaker's price suggests. Compare it with your own estimate to spot value.

South African online bookmakers use decimal odds exclusively, so the decimal field is where most SA bettors will start. Convert to American or fractional when reading international betting analysis or comparing odds at international sites.

Quick reference: common conversions

DecimalFractionalAmericanImplied %
1.501/2−20066.67%
1.9110/11−11052.36%
2.001/1 (Evens)+10050.00%
2.503/2+15040.00%
3.002/1+20033.33%
5.004/1+40020.00%
11.0010/1+10009.09%
21.0020/1+20004.76%

The maths behind it

Every odds format is just a different display of the same underlying probability. The conversion formulas:

  • Decimal → Implied probability: 1 ÷ decimal × 100
  • Decimal → Fractional: decimal − 1, expressed as a fraction
  • Decimal → American (positive): (decimal − 1) × 100, when decimal ≥ 2.0
  • Decimal → American (negative): −100 ÷ (decimal − 1), when decimal < 2.0
  • Fractional → Decimal: (numerator ÷ denominator) + 1
  • American → Decimal (positive): (american ÷ 100) + 1
  • American → Decimal (negative): (100 ÷ |american|) + 1

Continue learning

Common Questions

You asked.

Decimal odds (used in South Africa, Europe and Australia) show your total return per rand staked, including the stake: odds of 2.50 return R2.50 for every R1 bet. Fractional odds (the UK tradition) show profit against stake: 5/2 means you win R5 for every R2 staked. American odds use a positive number for the profit on a R100 stake (+250 means R250 profit on R100) or a negative number for the stake needed to win R100 (-150 means stake R150 to win R100). All three describe the same probability in different ways.

Implied probability is the chance of an outcome that the bookmaker's odds suggest, worked out as 1 ÷ decimal odds × 100. Odds of 2.00 imply 50%, 4.00 imply 25% and 1.50 imply 66.7%. Across all the outcomes in a market, the implied probabilities add up to more than 100%. The excess is the bookmaker's margin, also called the overround or vig.

Decimal odds are the SA standard, used by Hollywoodbets, Betway, Sportingbet, Supabets and every other SA-licensed operator. Most SA players never need fractional or American formats. The converter is most useful when comparing odds across international sites or reading betting analysis written for UK/US markets.

Two reasons. First, comparing bookmakers: even when both show decimal odds, you read prices faster when you can think in probabilities. Second, understanding what the price is saying: turning 2.50 into a 40% implied probability tells you the bookmaker rates this outcome at about four times in ten, which is far more useful for finding value than the decimal on its own.