What this calculation means
Required-purchase estimation works backward from a usable target and a measured yield. It answers how much starting material is needed before the stated preparation loss.
A zero yield cannot supply a positive usable target. Confirm the preparation and measured yield instead of replacing a missing yield with a default.
How to use this calculator
Enter the target usable quantity and a positive yield percentage. Keep the target and purchase record on the same named quantity unit.
Formula and variables
Required purchase quantity = Target usable quantity ÷ (Yield percentage ÷ 100)
- Target usable quantitysame unit
- Usable quantity required.
- Yield percentage%
- Usable proportion, such as 75 for 75%.
Quantity results display up to two decimal places. The calculation retains the underlying quantity; the display does not impose a whole-portion policy.
Understand your result
The result is a continuous as-purchased quantity. It does not round to supplier packs.
Worked example
Need 12 lb usable at 75% yield.
Target usable quantity: 12 same unit
Yield percentage: 75 %
- Express 75% yield as 0.75.
- 12 usable lb ÷ 0.75 = 16 purchased lb.
Example result: 16 purchase units
Frequently asked questions
Why do I divide by yield instead of multiply?
A target is the amount after loss. Dividing 12 usable pounds by 0.75 gives 16 purchased pounds, of which 75% is the required 12 pounds.
Does the answer round up to cases?
No. Convert the continuous requirement to a stated pack size in the package planner when cases are indivisible.