Expiration Date Calculator

Created by Joanna Michałowska, PhD candidate
Reviewed by Dominik Czernia, PhD and Jack Bowater
Last updated: Sep 30, 2022

This expiration date calculator helps you to find out 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 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 breakdown, 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 have 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 to calculate the expiration date? A practical example of the cosmetic expiration date

Let's imagine that you have a product manufactured on the 21st of December 2019. On the label, you can see the following information: "Best before 10 months from manufacture date." Our expiration calculator is here to help!

21/12/2019 + 10 months = 20/10/2020

There you go! Now you know you should use your product by October 20, 2020.

Joanna Michałowska, PhD candidate
Date of production
Shelf life
Expiration date
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