Expiration Date Calculator
A product made on March 15, 2026 with an 18-month shelf life expires on September 15, 2027. This expiration date calculator adds a shelf life to a production or purchase date and tells you the expiry date, how many days remain, and whether it has already passed. It handles days, weeks, months, and years, including the month-end edge cases like January 31 plus one month.
Quick answer
Expiration date = production date + shelf life.
Expiration
Expires January 15, 2028 (549 days left)
Expiration date
2028-01-15
Days remaining
549
What this tells you
- •Expiration date = production date + shelf life.
- •Days and weeks add exact day counts. Months and years move the calendar date forward.
- •When the target month is shorter, the date clamps to the month's last day, so January 31 plus 1 month is February 28.
- •The days-remaining count compares the expiry against today.
How to Use
- 1Enter the production, packaging, or purchase date.
- 2Enter the shelf life and pick its unit.
- 3Read the expiration date and the days remaining.
- 4An expired item shows how many days past expiry it is instead.
How It Works
Formula
expiration date = start date + shelf lifeFor day and week shelf lives, the calculator adds the exact number of days. For months and years it moves the calendar forward the stated number of months, keeping the same day of month where possible. A 6-month shelf life from March 15 lands on September 15, while one month from January 31 clamps to February 28 because February has no 31st.
Calculation note: values are processed in the order shown above, using the current input units.
Worked Examples
Canned food with an 18-month shelf life
18 calendar months forward, keeping the 15th.
Fresh milk, 14 days from packaging
Exact day count, no calendar month rules involved.
Medication bought January 31 with a 1-month supply window
February has no 31st, so the date clamps to the last day of the month.
Typical Shelf Lives
Common products and how long they usually keep, unopened and stored properly.
| Product | Typical shelf life |
|---|---|
| Fresh milk | 5-14 days |
| Eggs (refrigerated) | 3-5 weeks |
| Bread | 5-7 days |
| Canned vegetables | 1-5 years |
| Dried pasta | 1-2 years |
| Most medications | 1-5 years |
| Sunscreen | 3 years |
Common mistakes
- Counting from the purchase date when the label counts from production. Weeks can pass between the two for shelf-stable goods.
- Treating best-before as unsafe-after. Best-before marks peak quality, while use-by on perishables is the actual safety line.
- Ignoring the opened clock. Many products switch to a much shorter life once opened, whatever the printed date says.