Start from measurements or stated assumptions
The calculator requires a user-supplied extraction fraction. It does not assign a universal apple yield. Distinguish a measured fraction from an early design assumption before using the output.
Track pressed and finished juice separately
Pressed juice equals fruit input multiplied by the stated extraction fraction. Finishing losses are applied to that juice stream, not silently included in the fruit quantity.
Add a concentration calculation only when relevant
For a simplified soluble-solids balance, concentrate mass equals finished-juice mass times inlet concentration divided by outlet concentration. The difference is the calculated removed-water mass.
Understand the limits
The preliminary model assumes comparable mass-based soluble-solids measurements, no solids loss in evaporation and no added mass. Brix is used only as an approximation for compatible juice measurements. Aroma streams, chemical changes, fouling and equipment design require a more complete assessment.
Take the question into the route, equipment and enquiry pages. The useful outcome is a clearer brief, not a longer reading list.