Effective unit-price change
14.3%
Package shrink
12.5%
Same-value price for new size
$4.37
Annual cost difference
$14.97
Quick answer: To detect shrinkflation, divide the old price by the old quantity and the new price by the new quantity using the same unit. If the new unit price is higher but the shelf price looks the same, the product has shrinkflated—enter both into the calculator above to see the exact effective increase.
Practical guide
How to measure shrinkflation by unit price
- 1
Record the old price and net quantity from an older receipt or package.
- 2
Enter the new price and quantity using the same unit.
- 3
Compare old and new unit prices; separate the package-size change from the total effective increase.
Worked example
Example: $4 for 16 oz is $0.25/oz. $4 for 14 oz is about $0.286/oz—an effective unit-price increase of about 14.3% even though the shelf price is unchanged.
How to read the result
The unit-price change is the meaningful measure. A smaller package is not automatically worse if its unit price also falls.
Important limits: Use comparable products and the same unit. Promotions, reformulation, quality changes, and taxes can make a simple comparison incomplete.
Evergreen method
Compare usable cost, not package price
The durable comparison is price per common unit adjusted for the share you will actually use.
Formula
usable unit cost = price ÷ (quantity × usable share)Reproducible steps
- 1.Convert every option to the same unit.
- 2.Estimate the share your household will use before spoilage.
- 3.Choose the lower usable unit cost only if storage and cash flow also work.
Data note — Evergreen model: The formula works with your own inputs and does not depend on a specific price or year.
FAQ
Questions, answered
What is shrinkflation?
Shrinkflation is a reduction in package quantity with little or no matching reduction in shelf price, which raises the price per unit.
How do I calculate the hidden price increase?
Calculate old and new price per unit, subtract the old unit price from the new one, then divide by the old unit price.
Can the package get smaller without shrinkflation?
Yes. If the price falls proportionally, the unit price may stay the same. Compare unit prices before deciding.
How do I spot shrinkflation at the grocery store?
Compare the current package's net weight or count against older receipts or photos of the same product. If the price is the same or higher but the quantity is smaller, the unit price has risen — enter both into this calculator to see the exact effective increase.
Which grocery products shrinkflate the most?
Snacks, cereals, paper goods, and personal care items have seen the most documented shrinkflation in recent years. Comparing unit prices over time using a price book is the most reliable way to catch it across any product category.
Related
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