What is in this guide
Work out the cost per feeding day, not the price on the shelf sticker. A larger bag usually costs less per kilogram, but only checking a per-kilogram or per-day figure tells you whether the saving is real for your household.
Why the sticker price misleads
Retailers price larger packs to look attractively different from smaller ones, and a bigger number on the shelf does not automatically mean better value. The only reliable comparison is cost against a fixed amount, either weight or feeding days, calculated the same way every time.
Work out cost per kilogram first
Cost per kilogram = pack price divided by pack weight in kilograms.
Use this for a first pass across pack sizes of the food you already feed. Keep both figures in the same unit, and use the current shelf or online price rather than a remembered one, since pricing changes.
Then work out cost per feeding day
Cost per kilogram alone still misses how long a pack actually lasts your specific pet, because feeding amounts vary by weight, life stage and activity level.
Cost per feeding day = cost per kilogram multiplied by your pet’s daily feeding amount in kilograms.
Find the daily feeding amount from the pack’s own feeding guide for your pet’s current weight, not a guess. If your pet’s weight has changed recently, use the current weight rather than an older figure.
This single number, cost per feeding day, is the one that is genuinely comparable between two pack sizes of the same food. A larger bag with a slightly lower cost per kilogram is not better value if it will spoil, go stale or sit unused before you get through it.
Check what else changes the real cost
- Storage life. A large bag opened and left in humid conditions can lose freshness before it is finished. If you cannot store a large bag airtight, the saving may not survive to the last feed.
- Multi-buy and subscription pricing. Recalculate cost per kilogram using the actual price paid under the offer, not the single-pack price, and only count the saving if you would have bought that quantity anyway.
- Wastage and portion accuracy. An inaccurate scoop measurement changes how long a pack actually lasts compared with the stated feeding guide, which affects your real cost per day more than a small price difference between two pack sizes.
- Wet and dry mixed feeding. Compare each format separately using its own cost-per-day figure, then add them together, rather than averaging the two.
Keep the comparison within one food
This method compares pack sizes of the food your pet already eats. It is not a way to judge whether one brand of food is better than another, which depends on ingredients, suitability and your vet’s advice rather than price. Reading an Australian pet food label covers what to check on the label itself if you are considering a genuine change.
If portion accuracy or kitchen space is the real issue rather than pack size, sorting out where and how food is measured changes the maths more than a bigger bag does; see feeding station setup for a small kitchen.
Your next step: calculate the cost per feeding day for your current pack size before deciding whether the next size up is genuinely cheaper.
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