Pet Food Bag Duration Calculator (How Long a Bag of Kibble Lasts)
How many days a bag of dry food lasts for one or more pets, and what that costs per day, per month and per year, from the bag size and the daily ration.
Results
The dashed line marks the value you entered.
What this tool does
A bag lasts its weight divided by what the pets eat each day, so a 12 kg bag for one dog fed 250 g a day lasts 48 days. Take the daily ration from the feeding guide on the bag or your vet, adjusted to the animal's weight and activity — the pet food portion calculator can work it out — and count every pet that eats from the bag. The price per day is the fair way to compare bag sizes and brands, since a cheaper bag with a bigger ration can cost more. Manufacturers usually advise using an opened bag within roughly a month or two, so a very large bag for a small pet may not stay at its best to the end.
Formula
days = bag weight (g) ÷ (daily grams per pet × number of pets) · cost per day = price ÷ days
Variables
| Symbol | Meaning | Unit |
|---|---|---|
bg | Size of the bag | kg |
dr | Daily food per pet | g |
pt | Number of pets eating it | — |
pr | Price of the bag | — |
DY | Days the bag lasts | d |
CD | Cost of food per day | — |
CM | Cost of food per month | — |
BY | Bags a year | — |
CY | Cost of food per year | — |
FR | Compared with the usual advice for an open bag | — |
Worked example
- Size of the bag12 kg
- Daily food per pet250 g
- Number of pets eating it1
- Price of the bag40
- Days the bag lasts48 d
- Cost of food per day0.83
- Cost of food per month25.36
- Bags a year7.6
- Cost of food per year304
- Compared with the usual advice for an open bagLonger than that — a smaller bag may stay fresher
Limitations
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.
- The tool works with whatever currency you use for the inputs; it does not convert between currencies.