How to Read and Calculate Decimal Odds

The three calculations

DraftKings' terminology guide is one current operator reference for decimal odds. The arithmetic is independent of the operator:

• Gross return = stake x decimal odds
• Profit = stake x (decimal odds - 1)
• Raw implied probability = 1 / decimal odds x 100

For a 20-unit stake at 2.40, gross return is 20 x 2.40 = 48 units and profit is 48 - 20 = 28 units. The raw implied probability is 1 / 2.40 x 100 = 41.67%.

Reference table

What the probability does and does not mean

The reciprocal is a break-even conversion for that price. It is not automatically the true chance of the selection. In a multi-selection market, the reciprocals commonly sum to more than 100%, so comparisons should either retain that margin or use a stated normalization method. OpenStax provides the underlying probability terminology.

Common reading errors

1. Treating gross return as profit. At 2.40, the return includes the original stake.
2. Reading 1.20 as a 20% chance. Its raw break-even probability is 83.33%.
3. Comparing prices from different settlement rules. A 90-minute result and a to-qualify market are different products even when the team label matches.

Reconstruct a price from a receipt

A useful receipt check starts with four fields: accepted stake, accepted decimal price, settlement status and paid return. If a 16-unit winning stake at 2.75 is accepted in full, the expected gross return is 16 x 2.75 = 44 units and the expected profit is 44 - 16 = 28 units. If the receipt shows a different amount, look for a partial acceptance, void leg, dead-heat reduction, deduction or promotional condition before assuming the multiplication is wrong.

Keep full precision during a conversion and round only the displayed result. For example, 1 / 3.30 x 100 is 30.3030...%, normally shown as 30.30%. Reversing the rounded percentage gives 1 / 0.3030 = 3.3003, not exactly 3.30. That small difference is display rounding rather than a price change.

A compact reading routine

1. Confirm that the number is a decimal price rather than a probability or handicap line.
2. Multiply by stake for gross return.
3. Subtract stake once for profit.
4. Use the reciprocal only when a raw break-even percentage is useful.
5. Read the market and settlement wording before comparing another quote.

This sequence keeps payoff arithmetic separate from probability judgement. A price can be calculated perfectly while the underlying selection, time period or settlement rule is misunderstood.

Related resources

Use the odds conversion guide when another format is displayed, or the overround guide to compare complete markets.

Continue learning

• Next guide: How to Read and Calculate Fractional Odds
• Related guide: Lay Odds
• Definition: Decimal Odds

Assumptions and limitations

All examples assume the bet is accepted in full, settles as a win, and has no deduction, commission, boost condition or void leg. Operator settlement rules control the actual return. Raw implied probability is a price conversion, not an independently validated forecast.