Unit Price Calculator

What is unit price comparison?

Unit price comparison is the practice of calculating the cost per standard unit of measurement (per 100 grams, per liter, per piece) to objectively compare products of different sizes, brands, and package formats. The unit price strips away packaging differences and marketing claims to reveal which product is genuinely the best value.

Many stores display unit prices on shelf labels, but they are often in tiny print and may use different units for different products (price per ounce for one brand, price per pound for another), making direct comparison difficult. This calculator standardizes everything to the same unit so you can compare instantly.

How to calculate unit price

Divide the total price by the total quantity, then multiply by the standard unit size. For price per 100g: (price divided by weight in grams) multiplied by 100. For price per liter: (price divided by volume in milliliters) multiplied by 1000. The product with the lowest unit price offers the best value, assuming equal quality.

How to use this tool

Enter the price and quantity for each product you want to compare. Select the appropriate unit type (weight, volume, or count). The calculator normalizes all products to the same standard unit (per 100g, per 100ml, or per piece) and highlights the best value option.

Common supermarket pricing tricks

• Family size is not always cheaper. Sometimes the medium pack has a lower unit price than the "value" or "bulk" size.
• Different unit labels make comparison harder. One brand shows weight in grams, another in ounces — convert to the same unit before comparing.
• Shrinkflation: The price stays the same but the package gets smaller. Always check the weight, not just the price.
• Eye-level placement. Stores place higher-margin products at eye level. Check top and bottom shelves for better-value alternatives.

Supported units

• Weight: grams (g), kilograms (kg), ounces (oz), pounds (lb) — all compared per 100g.
• Volume: milliliters (ml), liters (L) — compared per 100ml.
• Count: pieces (pcs) — compared per piece.

Worked example

A 500 g jar of coffee costs $8.00 and a 750 g jar costs $11.40. Divide price by quantity: 8.00 ÷ 500 = $0.016 per gram versus 11.40 ÷ 750 = $0.0152 per gram. The larger jar is cheaper per gram, saving about 5%. Converting to a familiar unit — $16.00 vs $15.20 per kilogram — makes the comparison easier to read at a glance.

Common mistakes

The most common mistake is comparing prices in different units — dollars per pound against dollars per kilogram, or per sheet against per roll. Always convert to the same unit first. Shoppers also assume the biggest package is always cheaper per unit, which is not guaranteed. Finally, factor in waste: a lower unit price is no bargain if the product spoils before you use it.

Frequently asked questions

Is the cheapest unit price always the best buy?

Not necessarily. A lower unit price only saves money if you will actually use the product before it expires or goes stale. Buying 5 kg of rice at a great unit price is a good deal if your family eats rice regularly. Buying 5 kg of salad greens at a great unit price is wasteful if half of it wilts before you can eat it.

Why do organic products have higher unit prices?

Organic farming has higher production costs due to more labor-intensive practices, lower yields per acre, more expensive certification requirements, and smaller economies of scale. Whether the premium is worth paying depends on your personal priorities regarding pesticide exposure, environmental impact, and taste preferences.

Is the largest size always the best value?

No. While bulk sizes are often cheaper per unit, retailers sometimes price them higher, so always compare the unit price directly. Buying more than you can use before it expires also erases any saving.