How long will a bag of pet food last.

Worked example

A 12 kg bag fed at 250 g a day to one pet: 12,000 g ÷ 250 g = 48 days, or about 6.9 weeks. Opened on 2026-10-01 it runs out on 2026-11-18. With a 7-day cushion, reorder by 2026-11-11. At about 7.6 bags a year, that is a bag every 48 days. For two pets eating 250 g each, the same bag lasts 24 days.

How it works

Days = bag weight in grams ÷ (grams fed per pet per day × pets). Pounds and ounces convert at 1 lb = 453.59237 g and 1 oz = 28.349523125 g (the exact definitions). Cups need the grams-per-cup figure for your food, since cups of different foods weigh differently. The run-out date is the opening date plus the whole days, and the reorder date is that many days earlier.

Use the amount from the food’s feeding guide and your vet’s advice. Include treats if you want the date to reflect them. To also see what the bag costs per day, use the pet food cost per day calculator.

Sources and basis (checked 2026-10-08): arithmetic on the numbers you enter; no published price or rate data is used. Unit conversions use the exact international definitions of the pound and the ounce.

FAQ

How long will a 30 lb bag of dog food last?

Divide 30 lb (13,607.8 g) by the grams fed per day. At 250 g a day it lasts about 54 days. Enter your own numbers above.

How do I convert cups to grams?

Weigh one level cup of your food and enter the grams. It varies by food.

What if I feed several pets?

Enter the amount for one pet and the number of pets eating the same food. If their portions differ, add them together and enter 1 pet.

What does the reorder date mean?

It is the run-out date minus the days of lead time you choose, to allow for delivery or a trip to the store.

Do treats count?

Only if you add them to the daily amount.