Shrinkflation Calculator

How it works

old unit price = old price ÷ old size · new unit price = new price ÷ new size · real price change = (new unit price ÷ old unit price − 1) × 100 · fair price for the new size = new size × old unit price · extra per pack = new price − fair price

Shrinkflation is when a product gets smaller while its shelf price stays the same or rises, so the price per gram, ounce, sheet or piece goes up without a visible price change. Statistical agencies such as the US Bureau of Labor Statistics treat a smaller package at the same price as a price increase in the consumer price index, and this calculator does the same: it compares price per unit before and after. A package that shrinks 12.5% at an unchanged price is a 14.29% price rise per unit, because the same money now buys less.

Worked example

A snack that used to be 16 oz for $4.99 is now 14 oz for the same $4.99. The old unit price is $0.3119 and the new one $0.3564, a real price change of +14.29% per unit even though the shelf price changed 0.00% and the pack shrank -12.50%. At the old unit price the 14 oz pack should cost $4.37, so you pay $0.62 extra per pack.

Sources: US BLS — Quality adjustment in the CPI · Wikipedia — Shrinkflation

Frequently asked questions