Expiry Date & Shelf Life Calculator
Enter a product's manufacturing date and its shelf life, and this free calculator works out the expiry date, the total shelf life in days, how many days remain, and the remaining shelf life percentage — the numbers retailers, pharmacies, and grocery stores need for FEFO rotation and near-expiry decisions.
The Expiry Date Formula
Expiry Date = Manufacturing Date + Shelf Life. If a product was manufactured on 1 January 2026 with a shelf life of 6 months, its expiry date is 1 July 2026. The reverse formulas are just as useful: Total Shelf Life = Expiry Date − Manufacturing Date, and Remaining Shelf Life % = (Days Remaining / Total Shelf Life) × 100.
How It Works
- Find the manufacturing (production) date printed on the label — often marked MFG, MFD, or Packed On.
- Find the shelf life on the label or specification (for example, "use within 12 months of manufacture").
- Enter both values above and press Calculate.
- Read the expiry date, days remaining, and remaining shelf life percentage, then act on it: sell first, mark down, or remove.
Worked Example
A pharmacy receives a vitamin batch manufactured on 1 March 2026 with a shelf life of 18 months. Expiry date = 1 March 2026 + 18 months = 1 September 2027. If today were 1 March 2027, the batch would have 184 days remaining out of 549 total — a remaining shelf life of about 34%, so it should be prioritised for sale under FEFO rotation rather than left behind newer stock.
What the Remaining Shelf Life Percentage Means
- Above 50% — healthy stock, no action needed.
- 25–50% — monitor it, sell before fresher batches, plan promotions.
- Under 25% — act now: markdown, transfer between branches, or supplier return.
- 0% or negative — expired. Remove from sale and record the write-off.
Checking one product at a time is a start; tracking every batch automatically — with alerts before dates pass — is what prevents losses at scale. See how in the guide to free expiry tracking software for small businesses and the 7-step plan to reduce expiry losses in retail.
Frequently Asked Questions
Q: How do you calculate an expiry date from the manufacturing date?
Add the shelf life to the manufacturing (production) date: Expiry Date = Manufacturing Date + Shelf Life. For example, a product manufactured on 1 January with a 24-month shelf life expires on 1 January two years later.
Q: What is the shelf life formula?
Total Shelf Life = Expiry Date − Manufacturing Date. Remaining Shelf Life = Expiry Date − Today. Remaining Shelf Life % = (Remaining Shelf Life / Total Shelf Life) × 100.
Q: What does remaining shelf life percentage mean?
It shows how much of a product's usable life is left. Above 50% is healthy stock; 25–50% should be monitored and prioritised for sale; under 25% needs action — markdown, transfer, or use first under FEFO rotation.
Q: Is the expiry date the same as the best before date?
No. An expiry (use by) date is a safety limit — do not sell or use the product after it. A best before date is a quality guide; the product may still be usable afterwards, but taste, texture, or potency can decline.