Unit Price Calculator,
find the best grocery deal instantly.

Shopping guide

How to always buy the best value, every time.

The unit price illusion

Supermarkets are expertly designed to make price comparison difficult. Products are packaged in irregular sizes — 325g, 410g, 750g, 1.1kg — specifically to prevent mental arithmetic. Fonts for unit prices on shelf labels are often legally permitted to be smaller than price tags. Multi-buy promotions ("3 for $5") create artificial urgency that discourages careful comparison.

The unit price cuts through all of this. A single number — the cost per 100g, per 100ml, or per piece — tells you everything you need to make the right choice, regardless of package size, brand, or promotional framing.

When bulk isn't cheaper

The assumption that "bigger is cheaper per unit" fails more often than most shoppers realize:

• Sales on standard sizes: A 400g jar on promotion can undercut the unit price of a 1kg jar at full price. This is especially common for condiments, canned goods, and cleaning products.
• Store brands vs. name brands: A 300g store-brand product frequently has a lower unit price than a 1kg name-brand item, even accounting for the size difference.
• Shrinkflation: Manufacturers reduce package weight while keeping the price stable or slightly lower, raising the effective unit price. The 500g version of a product from three years ago might now be 450g.
• Perishables: The cheapest unit price on a 2kg bag of salad is irrelevant if half of it goes to waste. Factor in your realistic consumption rate for perishable items.

How unit conversion works

When comparing items measured in different units, you must normalize to a common base before dividing. This calculator converts all weight units (grams, kilograms, ounces, pounds) to grams before computing the per-unit price. Volume units (milliliters, liters, fluid ounces) are converted to milliliters. The result is always displayed as a standardized cost per 100g or per 100ml, making the comparison intuitive regardless of what units are printed on the packaging.

Weight and volume units cannot be directly compared — 100g of olive oil occupies a different volume than 100ml, and their densities differ. If you need to compare products sold by weight against products sold by volume (which sometimes happens with liquids), you would need the density of the product to convert — beyond the scope of a unit price tool.

Reading shelf labels correctly

In jurisdictions that require unit pricing, the unit price typically appears on the shelf label below or beside the product price, in a smaller font. Look for the words "per 100g," "per kg," or "per unit." If the units on two items differ (one in per 100g, another in per kg), multiply or divide to bring them to the same basis — or simply use this calculator instead.