A bet builder calculator shows how far a bet builder price sits below its parts. Take over 2.5 goals at 1.80, both teams to score at 1.85 and Saka to score anytime at 2.75. Multiply them like an acca and you get 9.16. The bet builder offers 7.00. That’s 23.6% less, and on a £10 stake £70 back instead of £91.58.
The gap isn’t always a rip-off. Enter your legs and the offered price in the free calculator above and it shows the difference, the implied chance and your return.
Bet builder calculator: why the price is lower
An acca’s legs come from different games, so they’re independent. A bet builder’s legs come from the same match, and they tend to happen together. If Saka scores, over 2.5 goals gets more likely. If both teams score, there are at least two goals already. Multiplying the prices would treat those as separate events and overpay, so bookmakers price the link in.
Then they add their margin, and it’s usually bigger than on a single market. A cut of 15% to 30% below the multiplied price is normal for three linked legs. Over 40% is worth a second look, either because the legs are almost the same bet or because the price is mean.
When the builder pays more
Occasionally the builder price is above the multiplied odds. That happens when the selections work against each other, like under 2.5 goals with both teams to score and a winner, which leaves only 2–1 or 1–2. It also happens with price boosts. The calculator flags it in green.
Comparing bookmakers
Bet builder prices vary more between bookmakers than single prices do, because each uses its own model for how the legs link. Put the same three legs into two bet builders and the prices can differ by 20% or more. The quickest check is the “How much lower” figure: lower is better. For bets across different matches, use the acca calculator, and for the chance hidden in any single price, the implied probability calculator.
Bet builders are easy to add to. Decide the stake before you start picking. BeGambleAware.org is free and confidential if it stops being fun.