Your receipt is lying to you. According to the Washington Post and Bureau of Labor Statistics (BLS) data, grocery prices have jumped 25.8% since 2020. But that number only tracks the currency leaving your wallet. It doesn't track the physical volume vanishing from your pantry.
That’s where the "Grocery Time Machine" comes in. This visualizer scrapes historical data from the Internet Archive / Wayback Machine to overlay 2019 packaging dimensions onto 2024 models. It reveals the "ghost items"—the missing ounces and grams that $100 used to buy you just a few years ago.
Most people blame general inflation. But when you look at the data, you see a specific, repeated pattern. Brands aren't just raising prices; they are adhering to a strict biological threshold known as Weber’s Law.
The Math Behind the Theft: Weber's Law
Corporations don't shrink products at random. They use a 19th-century psychophysics formula ($K = \Delta I / I$) to calculate the "Just Noticeable Difference" (JND). This is the exact moment a size reduction becomes visible to the human eye.
The magic number sits right around 9%. If a cereal brand cuts 15% of the flakes, you notice the bag is slack. If they cut 5%, the profit margin isn't worth the retooling costs. But a cut between 8% and 10%? That slips right past your conscious radar.
ð Key Takeaways
- The Math Behind the Theft: Weber's Law
- Beyond Shrinkflation: The "Skimp" and The "Greed"
- How to Beat the Algorithm
The Grocery Time Machine visualizes this "perceptual hack." It highlights how companies use Elongation Bias—shrinking a container's depth while keeping it the same height. Your brain prioritizes vertical lines, assuming the tall, thin box holds the same amount as the old, wide one. It doesn't.
Beyond Shrinkflation: The "Skimp" and The "Greed"
While the Consumer Price Index (CPI) tracks the sticker price, it fails to capture Skimpflation. This is where the box size stays the same, but the ingredients get worse. We see brands quietly swapping sunflower oil for water or reducing the cocoa content in chocolate bars.
Edgar Dworsky, the founder of Mouse Print* and the godfather of shrinkflation tracking, warns consumers to watch for the "Net Weight vs. Drained Weight" trick. A can of beans might weigh the same in your hand, but once you pour out the extra brine, you have 10% less food than you did last year.
Why go to these lengths? Because it pays. A 2023 report from the Groundwork Collaborative found that corporate profits drove 53% of inflation during the second and third quarters of that year. Senator Bob Casey has released multiple "Greedflation" reports utilizing similar data, arguing that companies used the cover of "supply chain issues" to permanently hike margins.
The visualizer confirms what the r/shrinkflation community has been crowdsourcing for years: the "Cost-of-living crisis" is partially a design choice.
How to Beat the Algorithm
Tools like CamelCamelCamel work great for Amazon hard goods, but for groceries, you need to change how you read the shelf. Here is how to spot the JND before you pay for it.
- The "Bridge Product" Trap. Watch out when a brand introduces a "Family Size" or "Party Size" alongside the regular version. Dworsky notes this is often a setup. They anchor you to the new size, then quietly kill the original standard size, effectively resetting the price-per-ounce baseline.
- Ignore the Box, Read the Orange Tag. Marketing teams spend millions testing package shapes to fool your eye. Don't look at the box. Look strictly at the Unit Pricing (price per ounce/gram). It is the only number on the shelf that strips away the packaging manipulation.
- Check Elasticity. The Time Machine shows that "inelastic" goods (eggs, milk, baby formula) see the steepest hidden hikes because brands know you have to buy them. Luxury items (chips, soda) often shrink faster but hike prices slower to keep you buying.
ð Worth Noting: But that number only tracks the currency leaving your wallet