Unit Price Calculator - Per Ounce, Gram & Count

The unit price calculator compares two products by the cost of a single standardized unit so you can see which package is the better value. Enter the shelf price and the package size for each product, pick the unit, and the calculator returns the cost per ounce, gram, milliliter, or item for both products, plus how much you save by choosing the cheaper one.

• • Grocery shopping: Pick the cheaper cereal, pasta, rice, or canned good when two boxes show the same brand in different sizes, and stop assuming that a bigger box is always a better deal.
• • Household staples and cleaning supplies: Compare paper towels, trash bags, laundry detergent, and dish soap across brands and sizes, then commit to the option that costs the least per roll, sheet, fluid ounce, or load.
• • Bulk and club-store trips: Decide whether the warehouse-size package is really a better value per unit than the grocery-store size, especially for items you might not finish before they expire.
• • Multi-pack vs single items: Compare a multi-pack of beverages, snacks, or travel-size toiletries against buying the same number of items separately to see if the bundle actually saves money per unit.

The result panel reports the cheaper product by name along with the savings per unit and the percent difference, so the next decision at the register takes seconds instead of guesswork.

When a sale tag shows a percentage off instead of a per-ounce price, switch to the Percent Off Calculator to convert the discount into the actual final price before comparing it with the other product.

The calculator reads both product entries, converts each package size into a single base unit, and divides the shelf price by that base size to produce a per-unit cost that is directly comparable.

• productAPrice / productBPrice: The shelf price you pay for each package, in the same currency. Prices must be positive numbers.
• productASize / productBSize: The package size in the unit you select. The calculator converts oz, lb, g, kg, mL, L, fl oz, and gal into a common base unit before dividing.
• productAUnit / productBUnit: The unit selector supports US customary, metric, fluid volume, and count, so 18 oz and 510 g can be compared without retyping the price.

When one product is in ounces and the other in grams, the calculator converts both to grams using the NIST factor 1 oz = 28.349523125 g before dividing.

The same approach is used in real estate when comparing rent or sale price per square foot: normalize the size to a single unit first, then divide the price by that size. The math is the same even when the unit is floor area instead of weight or volume.

According to US Federal Trade Commission, the FTC Unit Pricing Rule (16 CFR Part 245) requires retailers to display the price per unit of measure so consumers can compare value across package sizes and brands.

According to Consumer.gov, comparing unit prices is the standard way to find the best value among similar products because shelf prices reflect package size as well as brand.

The same per-unit formula is used in real estate when comparing rent or sale price per square foot and per square meter, and the Price Per Square Foot Calculator runs that comparison for floor area instead of weight or volume.

Four short concepts cover the math, the conversions, and the shelf-reference price that most grocers print on the price tag.

When the unit systems match (oz versus oz, g versus g, mL versus mL), no conversion is needed and the unit prices are read straight off the shelf.

Tracking which groceries cost the least per unit is a useful input for the Monthly Budget Calculator because it shows how the savings add up across an entire month of recurring shopping trips.

Five short steps take you from a confused aisle to a confident pick.

1. 1 Name each product: Type a short label for each option such as 'Brand A 12 oz' so the results panel tells you which is which.
2. 2 Enter the shelf price: Put the total price you pay for the package in the price field. Use the same currency for both products.
3. 3 Enter the package size and unit: Type the package size as it appears on the label and pick the unit. Ounces, pounds, grams, kilograms, milliliters, liters, fluid ounces, gallons, and count are all supported.
4. 4 Read the better-value answer: Look at the big result tile. It shows the name of the cheaper product, the savings per unit, and the percent savings so the decision is one glance.
5. 5 Use the per-100 reference to verify: Match the per-100-gram or per-100-mL row to the shelf tag when one is printed. If the shelf tag disagrees, double-check the package size or the unit.

A shopper compares a 4.99 dollar 12 oz box of pasta with a 6.49 dollar 18 oz box. The calculator reports Product B as the better value with 13.29 percent saved over the smaller box.

After picking the cheaper box, plug the chosen brand and size into the Grocery Calculator to estimate the total grocery spend for the week, then compare that total against your planned grocery budget.

The calculator removes the mental math that pushes most shoppers to grab the bigger box or the brand they trust.

• • Compare any two packages fairly: Mix ounces and grams, pounds and kilograms, fluid ounces and milliliters, and gallons and liters, and the calculator normalizes everything to a single base unit before dividing the price.
• • Catch inflated 'bigger value' claims: Bulk and club-store packages sometimes cost more per unit than the grocery-store size. A two-product comparison surfaces the gap so you stop paying extra for packaging that looks like a deal.
• • Match the shelf tag: The per-100-gram and per-100-mL outputs mirror the standard shelf-reference price most US retailers print, so you can sanity-check the calculator against the in-store sign.
• • Plan shopping lists and shared grocery runs: Use the per-item cost as the cleanest input for shared grocery math, so each housemate can pay a fair share of the bulk savings.

Because the calculator handles both weight and fluid volume in the same form, the same workflow works for cereal, rice, juice, and detergent, with only the unit selector changing.

When the bulk box is shared between roommates or family members, the per-item cost from this calculator becomes the input for the Split Bill Calculator so each person owes a fair share of the bulk savings.

The package size, the unit you pick, and the precision of the shelf price all change the answer in small but real ways.

• • The calculator does not convert between currencies. Use the same currency for both products, or convert one price first.
• • It does not account for waste, spoilage, or items you will not finish. A bulk package that is cheaper per unit can still cost more overall if half of it goes unused before the best-by date.
• • Unit price ignores quality and dietary fit. The cheapest per ounce is not always the right choice if the lower-priced product is lower in protein or active ingredient.

The same NIST conversion factors used here for the unit math also apply to other per-unit comparisons, such as ingredient cost in a recipe.

According to NIST, NIST Special Publication 811 defines the international avoirdupois ounce as exactly 28.349523125 grams, the pound as exactly 0.45359237 kilograms, the US fluid ounce as exactly 29.5735295625 milliliters, and the US liquid gallon as exactly 3.785411784 liters.

Once the cheaper brand is picked, the per-ounce or per-gram cost from this calculator becomes one of the direct inputs of the Recipe Cost Calculator for the per-serving cost of a recipe.