A recipe written as two parts, one part and one part describes relative volumes. It does not mean two whole bags of the first ingredient and one whole bag of each of the others unless those bags all contain the same usable volume.
The Potting Mix Ratio Calculator keeps the recipe and the purchase list together. Each ingredient has a volume part, package size in litres and package price. You can add or remove rows when your chosen medium uses a different number of ingredients.
A 120 litre batch with three ingredients
Consider a volume ratio of two parts cocopeat, one part compost and one part perlite. There are four parts altogether, so a 120 litre target assigns 60 litres to cocopeat and 30 litres each to compost and perlite.
The package order depends on the sizes you enter. With 20 litre cocopeat bags, 20 litre compost bags and 10 litre perlite bags, the calculator calls for three, two and three packages respectively.
| Ingredient | Litres in mix | Whole packages | Example cost |
|---|---|---|---|
| Cocopeat | 60 | 3 | PKR 1,200 |
| Compost | 30 | 2 | PKR 700 |
| Perlite | 30 | 3 | PKR 1,500 |
Those sample package prices produce a purchase cost of PKR 3,400. You still mix only 30 litres of the purchased compost. The second compost bag creates a leftover; it does not change the recipe to two parts compost.
A part needs a consistent measuring container
Use the same bucket, scoop or other volume measure for every ingredient. Weighing equal kilograms would create a different blend because the ingredients do not necessarily have the same bulk density.
For compressed products, confirm whether the package litres refer to the expanded material. A block weight is not a litre figure, and adding its kilograms to the package volume field would make the purchase calculation meaningless. The tool expects comparable, usable volume figures throughout.
The mixture is a chosen example rather than a recommendation for every crop or container. Water retention, aeration, ingredient quality and the plant's needs still matter. Changing the parts updates the litres allocated to each ingredient without choosing those horticultural properties for you.
Keep the batch size tied to real containers
Find the usable capacity first with Pot Volume Calculator or the bed fill with Raised Bed Soil Calculator. Then enter the litres you actually want to prepare here. If you already have an ingredient, its required volume still belongs in the recipe, while your shopping list can account for the stock you own separately.