What this calculator does
Enter a manufacture or purchase date and a shelf life, and this tool works out the expiry date, then tells you how many days remain, or how many days have passed since it expired. It is the same arithmetic whether you are tracking a bag of flour, a bottle of sunscreen or a batch of medication, once you know when it started and how long it is meant to last.
The shelf life on a label is not always given in the same unit, so this lets you enter it in days, weeks, months or years and converts internally. Months are handled calendar-style, so 6 months from 15 January lands on 15 July, not a fixed count of 180 days, which matters when months vary in length.
The formula
The expiry date is the start date plus the shelf life, added in whichever unit you chose. Days remaining is the gap between that expiry date and today, counted from midnight to midnight. A negative gap means the item is already past its date.
| Term | Meaning |
|---|---|
| Start date | The manufacture date, purchase date, or the date the item was opened, whichever the shelf life is measured from. |
| Shelf life | How long the item is expected to stay usable from the start date, in the unit printed on the label or packaging. |
| Status | A plain read of the days-remaining figure: expired, expiring soon (within a week), or fresh. |
The inputs explained
| Field | What to enter |
|---|---|
| Manufacture / purchase date | The date printed as the manufacture or purchase date, or the date you opened the item. |
| Shelf life | The length of the shelf life, in the unit selected next to it. |
| Shelf life unit | Whether the shelf life figure above is in days, weeks, months or years. |
When to use it
Pantry and fridge stock
Packaged food often gives a "best before" duration from the packing date rather than a printed expiry date. Entering the packing date and that duration gives a concrete date to write on the container.
Skincare and cosmetics
Many cosmetics list a shelf life in months from first opening rather than manufacture, often marked with a small jar icon and a number like 12M. Using the date you opened it as the start date gives the real expiry, not the printed manufacture date.
Medication and supplements
A pharmacy label sometimes gives a shorter in-use shelf life once opened than the original packaging expiry. Checking both dates against today catches whichever one comes first.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How many days are left at different shelf-life lengths?
The same purchase date, 30 days back, checked against a range of common shelf-life lengths.
| Shelf life | Expiry date | Status |
|---|---|---|
| 7 days | 24 Feb 2027 | Fresh, 185 day(s) left |
| 14 days | 24 Sep 2027 | Fresh, 397 day(s) left |
| 30 days | 24 Jan 2029 | Fresh, 885 day(s) left |
| 90 days | 24 Jan 2034 | Fresh, 2,711 day(s) left |
| 180 days | 24 Jul 2041 | Fresh, 5,449 day(s) left |
| 365 days | 24 Dec 2056 | Fresh, 11,081 day(s) left |
Questions
What counts as expiring soon?
This tool flags anything expiring within 7 days as expiring soon, and anything beyond that as fresh. It is a reasonable general cutoff, not a food-safety standard, so always follow the specific guidance on the product itself.
Is a best-before date the same as an expiry date?
Not quite. A best-before date is about quality, the food may still be safe to eat slightly past it. An expiry or use-by date is about safety, and the product should not be used after it. Enter whichever date or duration is printed on your item.
Why does the expiry date land on a different day than I expected for months?
Months are not a fixed number of days, so adding "6 months" moves the calendar month forward by 6 and keeps the same day of the month where possible, rather than adding a flat 180 days. This matches how most shelf-life labelling works.
Can I use this for a warranty or subscription instead of a product?
Yes. The maths is identical for anything with a start date and a fixed duration, such as a product warranty or a membership period, not just perishable goods.
For counting the days to or from any other specific date, see the days until a date calculator.