How to use the pet food bag duration calculator
- Enter the bag size.
- Enter the grams you feed each pet a day.
- Enter how many pets share the bag.
- Press Calculate.
Worked example
A 15 kg bag fed to one dog at 300 g a day.
- Bag size
- 15 kg
- Amount fed per pet per day (g)
- 300
- Number of pets eating it
- 1
- Weeks
- about 7.1
- Daily total
- 300 g
- Pets
- 1
Opened bags go stale: follow the storage advice on the pack.
Example values are illustrative; this result is produced by the same calculator above.
How we calculate it
Sources: Pure arithmetic / unit conversion on user inputs (no external constant)
Understanding your result
How long a bag lasts is its weight divided by what you feed each day. A 15 kg bag is 15,000 g, so feeding 300 g a day empties it in 50 days, about seven weeks. With two pets eating 300 g each, the same bag lasts 25 days.
The calculator does this for any bag size and daily amount, in kilograms or pounds, and for up to twenty pets sharing the bag.
Use it to plan when to reorder, to compare bag sizes, and to check that a bag is lasting about as long as it should. If a bag runs out much faster than expected, the scoop may be bigger than you think.
Common mistakes
- Using cups instead of grams. Cups vary a lot from food to food.
- Forgetting that several pets eat from the same bag.
- Not counting treats and toppers that come from the same stock.
- Entering the bag size in pounds while the toggle is set to kilograms.
- Ignoring the best-before date and storage advice on opened bags.
Good to know
- The Dog Food Calculator and Cat Food Calculator give a calorie-based daily amount to enter here.
- Weigh a level scoop once so you know how many grams it holds.
- Buying a bag that lasts longer than the storage advice allows can waste food.
Frequently asked questions
How long will a bag of dog food last?
Divide the bag size in grams by the daily grams you feed. A 15 kg bag fed at 300 g a day lasts 50 days.
How do I find the daily grams?
Use the Dog Food Calculator or Cat Food Calculator for a calorie-based amount, or weigh what you actually scoop.
What if I feed wet and dry food?
Run the calculation once for each food using the grams of that food you feed each day.
What should I do if my bag runs out faster than the answer?
The scoop may hold more than you think, or treats and toppers may be coming from the same bag. Weigh a level scoop to check.
Does the calculator allow for different foods?
Run it once per food using the grams of that food you feed each day.
Can I use pounds?
Yes. Switch the unit toggle to imperial and enter the bag size in pounds. The daily amount is always in grams.
Sources
- Pure arithmetic / unit conversion on user inputs (no external constant)
Related calculators
- Dog Food CalculatorFind out how many calories your dog needs each day and how many grams or cups of your dog's food that is — using the same energy formula vets use.
- Dog Food Cost CalculatorSee what it costs per day, month and year to feed your dog, from its calorie need and the price of the bag.
- Dog Food Cups to Grams CalculatorConvert cups of dog food to grams (and back) using the energy values printed on your bag.
- Cat Food CalculatorWork out your cat's daily calories and how to split them between wet and dry food.
Estimates only. Every pet is different — confirm with your veterinarian.