How We Calculate Expiration

Our "Freshness Calculator" and shelf-life estimates are not random guesses. They are the result of a structured algorithm that takes into account the food type, storage state (fresh, cooked, frozen), and common spoilage patterns.

The Formula

For any given food item, we determine the "Safe Window" based on:

Safe Window = (Base USDA Shelf Life) × (Condition Factor) - (Safety Margin)

1. Base USDA Shelf Life

This is the raw data provided by the USDA FoodKeeper database. For example, for "Ground Beef," the raw data might be "1-2 days" in the fridge.

2. Condition Factor

We adjust the base life based on the state of the food:

  • Unopened/Sealed: Often lasts longer than the standard estimate. We may apply a 1.2x factor for certain shelf-stable items.
  • Opened: Drastically reduces shelf life. For example, opened jarred sauce might drop from 1 year to 2 weeks.
  • Thawed: Food thawed in the fridge typically has 1-2 days of shelf life, regardless of its original "fresh" life.

3. Safety Margin

We subtract a "buffer" from the maximum safe time to account for real-world variables like:

  • Time spent in the "Danger Zone" (40°F - 140°F) during transport.
  • Home refrigerator temperature fluctuations.

"Best By" vs. "Use By"

It is crucial to understand the difference between dates on packaging:

  • "Best if Used By/Before": Indicates when a product will be of best flavor or quality. It is not a purchase or safety date.
  • "Sell-By": Tells the store how long to display the product for sale for inventory management. It is not a safety date.
  • "Use-By": The last date recommended for the use of the product while at peak quality. For infant formula, this IS a safety date.

Our calculator primarily focuses on safety ("Use By") rather than just quality.