You may use this calculator to answer the question “To dilute bourbon of proof x in order to achieve proof y, how much water must I add?”

Note that the calculator is non-dimensional — the value returned by the calculator will be in terms of the units used. Ounces can be used as easily as ml, liters, gallons, or what have you. For example, in order to reduce 750 milliliters of 142.7 proof bourbon to 90 proof, you would need to dilute the original volume with 439.17 milliliters of water.