How the calculation works
Days = bag weight in grams ÷ (daily grams × dogs); 1 lb = 453.592 g; cost a day = bag price ÷ days
A worked example
A 30 lb bag holds 13,608 g. At 300 g a day for one dog it lasts 45 days; at $59.99 that is $1.32 a day and about $40.26 a month.
Bigger bags, fewer trips, fresher food?
A larger bag usually costs less per kg, but once opened, kibble slowly loses aroma and fats can go stale. Many makers suggest finishing an opened bag within about six weeks; keep it closed, cool and dry.
Compare by price per kg
The cost per day only depends on the price per kg and the daily amount. Two bags at the same price per kg cost the same per day, whatever their size; the catalog ranks every bag by price per kg for that reason.
Common questions
How many cups are in a 30 lb bag?
About 120–150, at roughly 90–110 g per cup of kibble. Weigh a level cup of your own food: kibble size and density change the figure.
How long does an opened bag stay fresh?
Check the date on the bag; many makers advise using an opened bag within four to six weeks. A smaller bag can be the better buy if a large one would go stale.
Method: arithmetic from the label values you enter. Reviewed .