Unit Price Calculator

This calculator compares two products by what each unit actually costs. Enter each price and pack size, and it shows the price per unit for both, which one is cheaper, the percentage saving, and the cost of 1,000 units at the better price. The size boxes are labeled in grams, but any unit works as long as both products use the same one: ounces, fluid ounces, liters, sheets, rolls, tablets or loads.

Use it in the store aisle when shelf labels are missing, use different units for neighboring products, or quote a multipack price. It also replaces a dedicated price-per-ounce tool: enter the two sizes in ounces and the result is price per ounce.

The comparison assumes you will use everything you buy. A larger pack that goes stale or past its date before you finish it costs more per unit you actually use. If one product is on promotion, work out the sale price first with the discount calculator and compare that figure.

Unit pricing is the method behind the unit-price labels on supermarket shelves, standardized in the US by the NIST Uniform Unit Pricing Regulation (Handbook 130) and in the UK by the Price Marking Order 2004. Shelf labels sometimes use different units for similar products (per ounce vs per pound, per 100 g vs per kg), which is the main reason to calculate it yourself. The "cost of 1,000 units" line simply scales the lower unit price, which makes tiny per-gram figures easier to read.

Both quantities must be in the same unit before the result means anything. These are the conversions that come up most often on labels. Weight (oz) and fluid volume (fl oz) are different measures, so do not mix them unless the label gives both. For recipe-style measures such as cups and tablespoons, use the cooking measurement converter.

• Multipacks and "value" sizes: larger packs are often, but not always, cheaper per unit. Promotions on the standard size regularly beat the big pack, so check every time rather than assuming.
• Different concentrations: laundry detergent, squash and cleaning concentrate should be compared per load or per diluted liter, not per bottle volume.
• Count vs weight: compare tissues, paper towels and toilet paper by total sheets (rolls × sheets per roll), and diapers or tablets by count.
• Drained weight: for canned fruit, vegetables and fish, the drained weight on the label is the food you actually get.
• Tax and deposits: if one item carries a bottle deposit or is taxed differently, add it to the price first. The sales tax calculator gives the after-tax figure.
• Waste: a cheaper per-unit price only saves money if you use the whole pack.

In the US, unit-price labels are voluntary in many states and required in some; where they are used, the NIST Uniform Unit Pricing Regulation sets out how they should be shown. In the UK, the Price Marking Order 2004 requires most products sold by weight, volume or length to show a unit price, typically per kg, per liter or per 100 g/ml. In both countries, two neighboring products can be labeled in different units, so a quick calculation is still the safest check.