Starlight Tools

Unit Price Calculator

Compare package prices by cost per ounce, gram, pound, kilogram, fluid ounce, liter, or item. All math runs locally in your browser.

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Ranked Comparison

Rank Item Package Unit price Difference
Enter items and calculate to compare unit prices.

Mass, volume, and item counts are compared separately. Fluid ounces are volume; ounces are weight.

Formula and Assumptions

Unit price is calculated as package price / normalized package quantity. For example, a $6.99 package weighing 12 oz has a unit price of 6.99 / 12 = $0.5825 per oz.

The calculator converts compatible units before comparing. Mass conversions use 1 oz = 28.349523125 g and 1 lb = 16 oz. Volume conversions use US customary volume units, including 1 fl oz = 29.5735295625 ml and 1 cup = 8 fl oz. Count comparisons use item counts only.

It does not judge quality, freshness, coupons that apply at checkout, shipping, deposits, or taxes. Add those costs into the package price first if they affect your decision.

How to Use Unit Price When Shopping

Unit pricing makes different package sizes comparable. A large bag is not automatically the better value: the only fair comparison is the price divided by the amount you actually receive. Use the same comparison unit for every compatible item, then pick the lowest unit price when quality and expiration are acceptable.

Be careful with similar-looking labels. "Ounce" usually means weight, while "fluid ounce" means volume. A 16 oz bag of coffee and a 16 fl oz bottle of cleaner are not interchangeable measurements. This tool blocks mixed unit families so the ranking stays meaningful.

FAQs

What if the shelf tag already shows unit price?

Use this tool when shelf tags use different units, when you want to include coupons, or when online listings omit unit price.

Should I include tax, shipping, or bottle deposits?

Include them in the package price only if they change the final cost you are comparing.

Why can I not compare ounces and fluid ounces?

Ounces measure mass and fluid ounces measure volume. They only convert for a specific substance density, which is not assumed here.

Can I compare price per serving?

Yes, if each package lists the same serving definition. Use "item" for count-like servings or enter the serving quantity as the package amount.

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