Your purchase notes
Keep the details in one place.
Powder, tablets and ready-mixed bottles have different pack sizes. Use the mixing instructions to work out the prepared volume before comparing costs.
Write down the amount of powder or number of tablets per serving, and the volume of water stated on the label. Multiply that prepared volume by the number of servings in the pack.
Compare the cost per unit
Choose one consistent unit: pieces, kilograms, litres or prepared litres, as appropriate. Divide total cost by the quantity. Do not compare unlike product types on price alone.