Price Comparison Tool

What is unit price comparison and why does it matter?

Unit price comparison divides the total price of a product by its quantity (grams, ml, items, etc.) to find the price per unit. This makes it easy to identify the best value when comparing different package sizes. For example, a 500g box of cereal at $4.00 costs $0.80 per 100g, while a 750g box at $5.25 costs $0.70 per 100g — the larger box is cheaper per unit even though the total price is higher. Supermarkets often use this technique to make bulk sizes appear cheaper, but the unit price reveals the real value.

How many items can I compare at once?

You can compare up to 6 products simultaneously. The cheapest option per unit is highlighted automatically, so you can see at a glance which package size offers the best value without doing mental math in the aisle.

Why is the bigger package not always cheaper per unit?

Contrary to popular belief, larger packages sometimes cost more per unit than smaller ones. This happens when manufacturers know shoppers assume bulk is cheaper and price accordingly — a practice called "size premium pricing." A 2023 study of US supermarkets found that in roughly 25% of cases, the smaller package had a lower unit price. Always check the unit price rather than assuming the biggest box is the best deal.

How do I compare products sold in different units?

The calculator normalises all quantities to the same unit before computing the unit price. For example, if one product is sold per 100g and another per 1kg, the calculator converts both to a common unit (grams, kilograms, or whatever you choose) so the comparison is fair. This handles the common supermarket trick of listing some products per 100g and others per kilogram to make direct comparison harder.

Does the price comparison tool account for sales tax or VAT?

The calculator works with the prices you enter. If you enter the shelf price (pre-tax), the unit prices are pre-tax. If you enter the final price including tax, the unit prices include tax. For a fair comparison, make sure all products use the same basis — either all pre-tax or all tax-inclusive. In most countries, shelf prices already include VAT or sales tax, so entering the shelf price is correct.

Can I use this to compare products across different stores?

Yes. Enter the price and quantity from each store for the same product, and the calculator shows which store offers the best unit price. This is particularly useful for bulk purchases where a small per-unit difference adds up — a $0.02 per unit difference on a 500-unit purchase saves $10.

Input: Product A: 500 g for $4.00 vs Product B: 750 g for $5.50

Result: Product A: $0.008/g. Product B: $0.00733/g. Product B is 8.3% cheaper per gram.