What is dutching?
Dutching means backing more than one selection in the same event and sizing the stakes so that each one returns the same amount if it wins. The stake on each selection is proportional to 1 divided by its decimal odds.
It only makes a profit when the combined implied probability of your selections is below 100%. The calculator shows that figure, so you can see straight away whether the prices add up. Covering every outcome of an event at different bookmakers to lock in a profit is arbitrage: our arbitrage calculator is built for that.
The formula
Stake on a selection = total stake x (1 / its decimal odds) / (sum of 1 / decimal odds for every selection). With £70 on 2/1 (3.0) and 3/1 (4.0): the shares are 1/3 and 1/4, which sum to 7/12, so the stakes are £40 and £30 and either winner returns £120.