Why Price Per Tub Misleads

Two fibre supplements can look similarly priced on the shelf and still cost very differently per gram of actual fibre. A cheaper tub with fewer serves, or less fibre per serve, can end up costing more per gram than a pricier one that delivers more fibre per serve. This is the same problem Australia's unit pricing rules exist to solve for groceries generally, comparing by weight or volume rather than sticker price, but unit pricing compares pack size, not the specific nutrient you're actually buying the product for. Price per tub, or even price per serve, skips the number that actually matters here.

The Formula

Cost per gram of fibre = price ÷ (number of serves × grams of fibre per serve). The result tells you what one gram of fibre actually costs from that product, which is the only like-for-like comparison between two different supplements.

Where to Find Each Number on an Australian Label

The pack price is on the shelf or online listing. Serves per pack and fibre per serve both come from the nutrition information panel, specifically the "servings per pack" line and the "Dietary Fibre" row. See our guide to reading the Australian nutrition information panel for what else is on there and why fibre is sometimes missing entirely.

A Worked Example

Say a supplement costs $30 for a tub of 30 serves, with 5g of fibre per serve. That's 30 × 5 = 150g of total fibre in the tub, so $30 ÷ 150g = $0.20 per gram of fibre. A second product costs $22 for 20 serves at 4g of fibre per serve: 20 × 4 = 80g of fibre, so $22 ÷ 80g = $0.275 per gram. The first product looks more expensive on the shelf but is actually the better value per gram of fibre. (These are invented, round numbers for illustration, not any real product's figures.)

Calculator

Enter a price, the number of serves in the pack, and the grams of fibre per serve, to get the cost per gram of fibre.

Cost per gram of fibre: —

Sources

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