Typically, you can expect a yield of about 80% when converting butter to ghee, meaning you'll lose approximately 20% of the original butter's weight due to water evaporation and milk solid removal.
When making ghee, you're essentially removing the water and milk solids from butter. Butter is composed of fat, water, and milk solids. The process of making ghee involves heating the butter slowly, allowing the water to evaporate and the milk solids to separate and eventually brown. These browned milk solids are then strained out, leaving behind pure butterfat, which is ghee.
The exact yield can vary slightly depending on the butter's original moisture content and the efficiency of your straining process. Butter with a higher water content will naturally result in a lower ghee yield. Similarly, if you don't strain out all the milk solids, the final weight of the ghee will be slightly higher, but the quality might be compromised.
For example, if you start with 1000 grams of butter, you can generally expect to end up with around 800 grams of ghee. The remaining 200 grams represents the water and milk solids that were removed during the process.
Use unsalted butter for making ghee to avoid any salty taste in the final product. Salt can also interfere with the separation of milk solids.