Pet Food Calculator
Knowing how long a bag of food lasts and what it costs each month makes pet budgeting simple. This calculator takes the daily feeding amount from your food label or veterinarian, the bag weight, and the price per bag, then returns how many days a bag lasts, how many bags you use per month, the monthly cost, and the cost per day. It never sets the portion for you, because the correct amount depends on your pet and the food, so you provide the daily grams and the tool does the rest.
Pet food formula
Days a bag lasts = bag weight / daily amount
Bags per month = (daily amount * 30.4) / bag weight
Cost per month = bags per month * price per bag
Cost per day = price per bag / days a bag lasts
The math uses 30.4 days as the average month length. Bag duration is bag weight divided by daily amount; the rest follows from your price per bag.
Feeding context
- The FDA regulates pet food labels, including feeding directions.
- Daily amount depends on weight, age, activity, and calorie density.
- Split the daily total into two or more meals as your vet advises.
- An average month is about 30.4 days, used for monthly figures.
- Weigh portions rather than using cups for the most accurate amount.
Pet food: frequently asked questions
How much should I feed my pet each day?
Feeding amount depends on your pet's species, weight, age, and activity, and the calorie density of the food. The amount on your food packaging or from your veterinarian is the right input here. This calculator does not set the portion; you enter the daily grams your vet or label recommends.
How long will a bag of food last?
Bag duration is the bag weight divided by the daily feeding amount. Enter both in the same unit (grams). The calculator returns how many days the bag lasts and how many bags you will use per month, so you can plan purchases.
How is monthly cost calculated?
Monthly cost is the number of bags used per month multiplied by the price per bag. Bags per month is derived from your daily feeding amount and the bag weight, so the cost reflects your pet's actual consumption and your supplier's price.
Should I split the daily amount into meals?
Many pets do better with two or more meals a day, but the total daily amount stays the same. To find the per-meal portion, divide the daily amount the calculator uses by the number of meals you feed. The cost and duration outputs depend only on the daily total.
Where can I find trustworthy feeding guidance?
The U.S. Food and Drug Administration regulates pet food labeling and provides guidance on reading labels. Your veterinarian and the feeding chart on the product are the most reliable sources for the daily amount to enter. This tool turns that amount into duration and cost.
Official sources
- U.S. Food and Drug Administration: Pet food labels, general.
- U.S. National Institute of Standards and Technology: Mass and time units.
Reviewed by the CalculatorHub team, edited by James Graham, 16 June 2026. See our methodology.