Double and treble bets: how the stake and return are calculated

A treble is one bet on three selections, and a double is one bet on two. Multiply the decimal odds of the legs, then multiply by the stake to get the return. Every leg must win: at 1.80, 2.50 and 1.60 the combined odds are 7.20, so KES 200 returns KES 1,440.

By BetSmart Kenya Editorial (prepared with AI tools under our editorial policy) · Last updated 2026-10-28

Single, double and treble in one table

A single is one bet on one selection. A double is one bet on two selections, and a treble is one bet on three. Longer bets of the same kind are called accumulators, and the full method is in how to calculate accumulator odds and payout.

In every case you place one stake. The bet wins only when all of its selections win, and each selection is called a leg.

The formulas

Decimal odds include the stake. A price of 2.50 means KES 2.50 comes back for each KES 1 staked, so the stake is part of the return and profit is what is left after taking it out.

Fractional prices must be converted first. The guide on decimal vs fractional odds shows the conversion, and 11/10 becomes 11 ÷ 10 + 1 = 2.10.

Why the stake rolls from leg to leg

Think of the bet as two or three singles in a chain. The whole return from leg 1 becomes the stake on leg 2, and the whole return from leg 2 becomes the stake on leg 3. Multiplying the odds gives the same answer as this chain.

The combined odds are 1.80 × 2.50 × 1.60 = 7.20. The return is 200 × 7.20 = KES 1,440, and the profit is 1,440 − 200 = KES 1,240. The first two legs on their own form a double at 1.80 × 2.50 = 4.50, which would return 200 × 4.50 = KES 900 and a profit of KES 700.

If any one leg loses, the return is KES 0 and the full KES 200 is lost. Winning the first two legs and losing the third pays nothing.

How implied probabilities multiply

Each price implies a probability of 1 ÷ decimal odds. For legs that do not affect each other, the chance that all of them win is the product of the separate chances. The guide on the chance of winning an accumulator covers the independence condition in more detail.

For the example, the implied probabilities are 1 ÷ 1.80 = 0.5556, 1 ÷ 2.50 = 0.4000 and 1 ÷ 1.60 = 0.6250. Their product is 0.5556 × 0.4000 × 0.6250 = 0.1389, or 13.89%. That equals 1 ÷ 7.20 = 0.1389, so the treble is priced as roughly a 1-in-7 event.

Notice that the chance of winning falls much faster than any single leg suggests. Legs that each look more likely than not (55.56%, 40.00% and 62.50% implied) combine to under 14%.

How the margin compounds

A bookmaker's prices carry an overround: the implied probabilities of a market add to more than 100%. The meaning is set out in what is overround. When you combine legs, the overround of each leg multiplies into the bet.

The average return per KES 1 on one leg is 0.50 × 1.9048 = 0.9524, so a single costs 4.76% of the stake on average. For a double, the chance of both winning is 0.50 × 0.50 = 0.25, and the combined odds are 1.9048 × 1.9048 = 3.6281, which is 1 ÷ (0.525 × 0.525) = 1 ÷ 0.275625. The average return is 0.25 × 3.6281 = 0.9070.

The same steps give the treble: the chance of all three is 0.125 and the combined odds are 1 ÷ (0.525 × 0.525 × 0.525) = 1 ÷ 0.144703 = 6.9107. The average return is 0.125 × 6.9107 = 0.8638. The pattern is that the implied probabilities multiply by 1.05 per leg, so n legs carry an overround of 1.05 to the power n, minus 1.

The average cost is a long-run figure over many bets of the same kind, not a prediction for one bet. The full explanation is in why accumulators carry more margin, and the table shows that the cost per shilling staked roughly triples from a single to a treble under these assumptions.

When a leg is void or cancelled

A void leg is one the operator cancels under its rules, for example because the event does not take place. A common convention is to settle that leg at decimal odds of 1.00, so it neither adds to nor removes from the combined odds. The bet then carries on with the remaining legs.

The combined odds become 1.80 × 1.00 × 1.60 = 2.88, and the return if the other two legs win is 200 × 2.88 = KES 576. A treble with one void leg is then a double. A double with one void leg becomes a single on the remaining leg, and if every leg is void the odds are 1.00 and the stake is returned.

This is only a convention. Some terms may cancel the whole bet instead, so the displayed rules decide, and the guide on void bets and pushes explains the stake maths for a single leg.

What the rules say about the stake

Section 71(1) of the Gambling Control Act, 2025 provides that a player in an online gambling activity shall not bet an amount of less than twenty shillings in a competition. A double or a treble has one stake, so the minimum is read against that stake. The minimum online stake guide covers what the section does and does not say.

Regulation 23(1) of the Gambling Control (Conduct of Gambling Operations) Regulations, 2026 requires a licensee to clearly display betting odds, rules and terms. Rules on voided legs, rounding and payout caps therefore belong in the operator's displayed terms, and your own calculation is a check on them.

Checking your own working

• Multiply, do not add. Odds of 1.80 and 2.50 combine to 4.50, not 4.30.
• Subtract the stake for profit. A return of KES 1,440 on a KES 200 stake is a profit of KES 1,240.
• Keep four decimals. Round only the final amount.
• Remember the full stake is at risk. A treble that fails on the last leg loses everything staked.

A bigger possible return does not mean a better bet. Fix the amount you can afford to lose before staking, as described in setting a betting budget and limits. Gambling is addictive. Play responsibly.