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Expiration Date Calculator

Created by Joanna Michałowska, PhD
Reviewed by Dominik Czernia, PhD and Jack Bowater
Based on research by
Food Product Dating; US Department of Agriculture; Oct 02, 2019
Last updated: Jan 18, 2024

This expiration date calculator helps you determine how long your product is good to use. In the article below, you will find out how to calculate the expiration date and how to use our expiration calculator (or shelf life calculator, if you prefer).

Do you find it confusing to calculate dates and add/subtract days? 📅 Check out our other time tools:

How to read expiration dates - is the sell-by date the expiration date?

There are a few phrases used on products for date-labeling. They include:

  • "Best if Used By/Before" — The product will have the best flavor or quality within this date. It is not a purchase or safety date.

  • "Sell-By" — This date tells the store how long to display the product for sale, helping with inventory management. So, is the sell-by date the expiration date? No, it isn't.

  • “Use-By" — This date is the last date recommended for the use of the product while at peak quality. It is not a safety date (except for when used on infant formula).

  • Expiration date (EXP) — According to Cambridge Dictionary this is "the last day on which a product or service can be used". However, according to USDA, foods are still safe for consumption after expiration dates pass. A consumer should make sure to look out for an off odor, flavor, or texture that means the food has spoiled and should not be eaten. To learn about the cosmetic expiration date, check the section below.

The regulations regarding date labeling may differ depending on the country. Please, check your local regulations.

Shelf life and cosmetic expiration dates

A product’s “shelf life” means the length of time you can expect a product to look and act as expected and to be safe for use. This time can vary depending on the type of product, how it is used, and how it is stored.

Cosmetics, like most products, start to degrade over time. It can be caused by the preservatives breaking down, exposure to bacteria and fungi while using (e.g., mascaras), exposure to moisture, separation of emulsions, etc. In the U.S., there are no laws or regulations that require cosmetics to have specific shelf lives or expiration dates on their labels.

Don't worry if you can't see a specific date on a product; manufacturers are responsible for making sure their products are safe. Remember that the length of time you can safely use your cosmetics also depends on you. Store them properly, keep containers and applicators clean, and try not to share makeup.

How to use the expiration date calculator?

Using the expiration calculator is really easy. Just follow these steps:

  1. Enter the starting date, e.g., production date or the date of first use.
  2. What is the shelf life of the product? Enter the number of days, weeks, months, years, or years and months.
  3. That's it! You will see the final date your product is still valid and good to use.


How do I calculate the expiration date?

Suppose you have the date a product was manufactured, and the label shows the following information: "Best before 10 months from manufacture date."

  1. Write down the date the product was manufactured.
  2. Add the best-before period to the date the product was manufactured.

There you go! Now you know the expiration date.

How do I know the expiration date of a product?

A product's expiration date is usually written on the outside of the container. However, date labeling is voluntary except for products meant for consumption by infants.

Are eggs good after the expiration date?

Yes. Eggs are usually good after the best before date. However, the quality of your eggs after this date, as with most things, is often dependent on how they are stored.

You should check the egg for any change in color, taste, or texture if you intend to use it after this date. Additionally, eggs used after this date should be well-cooked to avoid health risks.

What is the expiration date of a product with a best before date of 36 months?

Assuming that the date of manufacture is December 01, 2022, the expiration date is December 01, 2025.

To calculate this, add 36 months to the date the product was manufactured. This is exactly three years from the date the product was manufactured.

Joanna Michałowska, PhD
Date of production
Shelf life
Expiration date
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