Double Bets Explained: Two-Leg Odds and Settlement

Two legs, one combined payoff

Betfair's current placement guide uses a double as an operator example of a multiple in which both selections must win. A void or push can shorten the bet to a single under the applicable rules.

For illustrative accepted prices 1.80 and 2.10:

Combined price = 1.80 * 2.10 = 3.78

For a GBP 10 stake:

Gross return = 10 * 3.78 = GBP 37.80

Net profit = 37.80 - 10 = GBP 27.80

Joint probability check

Suppose an illustrative model estimates probabilities 0.58 and 0.49. If and only if the events are independent:

Joint probability = 0.58 * 0.49 = 0.2842, or 28.42%

OpenStax explains the independence requirement. Two different matches are not automatically independent: shared team news, weather, competition incentives or the same model error can connect them. Same-match legs need a joint or conditional estimate.

Decision record

• Exact market and settlement period for each leg.
• Accepted price and model probability for each leg.
• Information cutoff and evidence used.
• Dependence rationale or joint model.
• Void, push and non-runner rules.
• Gross return, net result and any early settlement.

Use OpenStax's expected-value method only after the complete payoff states and probabilities have been defined.

Next step

Use Treble Betting Strategy for the next part of this topic.

Compare the double with two singles

The same two selections can create different cash outcomes depending on structure. With GBP 5 on each single at illustrative prices 1.80 and 2.10, total stake is GBP 10. If only the first selection wins, the singles return GBP 9.00. A GBP 10 double returns nothing because both legs are required. If both win, the singles return GBP 19.50 while the GBP 10 double returns GBP 37.80, but the exposures are not stake-equivalent by leg.

This is a payoff comparison, not a recommendation. To compare value, attach estimated probabilities to every outcome state and use net payoffs. Also check whether the two events share information, competition incentives or model errors; playing on different dates does not by itself prove independence.

Continue learning

• Next guide: System Bets Explained
• Related guide: Treble Bets Explained
• Definition: Double Bet

Assumptions and limitations

The example is illustrative and ignores caps, deductions, free bets, boosts, cash out and tax. A double reduces the number of required outcomes relative to a longer accumulator, but that alone does not make it positive expected value.