An accumulator bet combines multiple selections into one, requiring all selections to be correct for a payout. It offers higher potential payouts but carries greater risk. Odds are calculated by multiplying the odds (decimal) of each bet together to make one big bet. An accumulator bet combines multiple selections into one, requiring all selections to be correct for a payout. It offers higher potential payouts but carries greater risk. Odds are calculated by multiplying the odds (decimal) of each bet together to make one big bet.