A pantry inventory and food-waste log with a fixed weighing rule

Goal

Know what food is in the house and what leaves it uneaten, in numbers that a second household could produce the same way.

Prerequisites

A kitchen scale, a list on paper, in a spreadsheet or in a plain-text file, and one place where discarded food is weighed before it goes to compost or bin. The FAO platform on food loss and waste defines food waste as the decrease in the quantity or quality of food resulting from decisions and actions by retailers, food service providers and consumers; a household log covers the last of these three.

Steps

1. Inventory once: for every item, the name as on the package, the quantity as printed (count, mass or volume), the printed date copied verbatim together with its label ("best before", "use by", or none), the storage location (shelf, fridge, freezer) and the date of entry. The log copies the printed date; it does not interpret it.
2. Purchases: add each item on the day it enters the house with the same fields. A receipt is the easiest source for names and counts.
3. Discards: every time food is thrown away, weigh it, edible and inedible parts separately where practical (peel versus flesh), and log the mass in grams, the item, the reason from a fixed list (judged spoiled by you, past printed date, leftover not eaten, cooked too much, other), and the printed date if any.
4. Weekly, reconcile the list against the shelf: an item that vanished without a purchase or discard entry gets an "unlogged" row rather than a silently corrected count.
5. Monthly, total the discarded mass by reason and list the ten items with the largest discarded mass, with the month's purchase count next to them. Keep the raw rows.
6. Report the definitions used (the reason list, the edible-versus-inedible rule), the scale's resolution and how many discards were estimated instead of weighed.

Expected result

A month's discard total in grams with reasons, beside an inventory whose accuracy is known from the weekly reconciliation.

Limits and test basis

Proposed protocol; no household figure is claimed. The protocol says nothing about whether food is safe to eat: the "judged spoiled" reason records your judgement, not a fact about the food. Liquids poured away are hard to weigh; note them by volume. Mass includes water, so comparing bread with soup by grams compares mass and nothing else.