Unit Price Calculator
Compare prices per unit to find the best value. Enter price and quantity for up to three products — find the cheapest per ounce, per gram, or per unit instantly.
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Enter your values above to see the results.
Tips & Notes
- ✓Larger packages are not always cheaper per unit — promotional pricing on smaller sizes and unit price floors at wholesale clubs can make medium sizes more economical. Always check the shelf tag unit price.
- ✓Unit price tags are required in most US supermarkets. Find the small print on the shelf label showing price per ounce, pound, or count — use this for instant comparison without a calculator.
- ✓Compare in the same unit — price per ounce for solid products, price per fluid ounce or per mL for liquids. Mixing units (comparing price per liter with price per gallon) gives misleading results.
- ✓Factor in waste when comparing — a cheaper product you use less of (concentrated cleaning products, quality ingredients) may actually cost less over time than a cheaper per-unit diluted option.
- ✓For perishables, factor in usage rate — a large package with a lower unit price is a worse value if you cannot use it before it spoils. Calculate per-serving cost based on realistic usage.
Common Mistakes
- ✗Comparing products in different units without converting — $0.30/oz vs. $4.50/lb: convert the per-pound price first (4.50/16 = $0.28/oz) to find the per-pound product is actually cheaper.
- ✗Ignoring waste factor for perishables — a 5-lb bag of salad at $0.40/oz sounds better than a 10-oz bag at $0.60/oz, but if you throw away 3 lbs, the effective cost is much higher.
- ✗Not accounting for concentration differences — a concentrated detergent at $0.25/fl oz may actually clean 3× as many loads as a diluted one at $0.15/fl oz, making the concentrated one cheaper per load.
- ✗Comparing net weight and gross weight as if equal — "12 oz net weight" means 12 oz of product; 12 oz total package weight includes packaging. Always compare net weights.
- ✗Ignoring store brand vs. name brand quality differences — unit price optimization only applies when comparing similar quality products. A lower unit price on a product you will not use is not a good deal.
Unit Price Calculator Overview
Unit price comparison is the single most effective tool for reducing grocery and household spending. Studies consistently show shoppers who compare unit prices spend 7-13% less on the same basket of goods — without changing their purchasing behavior or accepting lower quality.
Unit price formula:
Unit Price = Total Price / Quantity | Best Value = Lowest Unit Price
EX: Orange juice — 52 fl oz for $3.49 vs. 89 fl oz for $5.29. Unit price A = $3.49/52 = $0.0671/fl oz. Unit price B = $5.29/89 = $0.0594/fl oz. The larger 89 fl oz container is 11.5% cheaper per ounce → choose B (if you will use it before it expires).Common unit conversions for comparison:
| From | To | Multiply By | Example |
|---|---|---|---|
| Price per lb | Price per oz | ÷ 16 | $4.80/lb → $0.30/oz |
| Price per oz | Price per lb | × 16 | $0.30/oz → $4.80/lb |
| Price per kg | Price per 100g | ÷ 10 | $6.00/kg → $0.60/100g |
| Price per liter | Price per fl oz | ÷ 33.814 | $2.00/L → $0.059/fl oz |
| Price per gallon | Price per fl oz | ÷ 128 | $3.50/gal → $0.027/fl oz |
| Price per 100 | Price per item | ÷ 100 | $12.99/100ct → $0.13/item |
| Scenario | Small Package | Large Package | Savings Per Year |
|---|---|---|---|
| Laundry detergent | $8.99/50 loads = $0.18/load | $21.99/150 loads = $0.147/load | ~$22/year (156 loads) |
| Paper towels | $1.29/roll (60 sheets) | $14.99/12 rolls (60 sheets) | $0.04/roll savings |
| Olive oil | $8.99/16.9 fl oz = $0.53/fl oz | $19.99/51 fl oz = $0.39/fl oz | ~$16/year (100 fl oz use) |
Frequently Asked Questions
Divide the total price by the number of ounces. Example: a 28-oz jar of pasta sauce costs $3.49 → $3.49 / 28 = $0.1246 per ounce. A 14-oz jar costs $2.19 → $2.19 / 14 = $0.1564 per ounce. The 28-oz jar is cheaper at $0.125/oz vs $0.156/oz — a 20% better value. This calculation applies to any unit: price per gram, price per mL, price per count. Divide total price by total quantity in the unit you want to compare.
Not always. Promotional pricing on standard sizes, manufacturer coupons, and store brand products can make smaller sizes cheaper per unit. For example, Costco peanut butter at $0.12/oz may be beaten by a store brand 40-oz jar at $0.10/oz during a sale. Additionally, for perishables, the per-unit advantage disappears if the product spoils before use. Non-perishable pantry staples, cleaning supplies, paper products, and personal care items at warehouse clubs consistently offer the best unit price value for items with long shelf life.
Use a consistent unit within each comparison. For food products: compare solid foods in price per ounce (weight) or price per gram; compare liquids in price per fluid ounce or price per mL or per liter. Never mix weight ounces and fluid ounces — 1 weight oz of olive oil occupies about 0.96 fl oz of volume. For practical purposes: 1 fl oz of water ≈ 1 oz by weight (water density ≈ 1 g/mL), but cooking oils, juice, and most other liquids differ. When comparing unit prices on a shelf, both products should be in the same unit on the label.
Calculate cost per use, not cost per unit volume. If a concentrated cleaner costs $8 for 32 fl oz and dilutes 1:10 (1 part cleaner to 10 parts water), it makes 352 fl oz of ready-to-use solution at $0.023/fl oz of solution. A ready-to-use cleaner at $4 for 32 fl oz costs $0.125/fl oz of solution. The concentrated option is 5× cheaper per fl oz of ready-to-use product. Apply this "per use" or "per prepared serving" approach to protein powder, juice concentrate, and any other concentrated products.
In the United States, unit pricing is required by law in most states, though the specific rules vary. California, Connecticut, Maryland, Massachusetts, New Jersey, New York, and several other states require unit prices on all food products. Many major retailers (Walmart, Target, Kroger) display unit prices voluntarily nationwide. The unit price label is typically the small print on the yellow or white shelf tag below the product, showing price per ounce, per pound, per liter, or per count depending on the product type. Federal regulations under the Fair Packaging and Labeling Act require net quantity disclosure on packaging but do not mandate shelf unit pricing.
Divide total price by number of servings. Example: cereal box A: $4.99, 12 oz, serving size 1 oz (12 servings) → $4.99/12 = $0.416 per serving. Cereal box B: $3.49, 9 oz, serving size 3/4 oz (12 servings) → $3.49/12 = $0.291 per serving. Per serving, Box B is cheaper despite having fewer ounces. Per ounce: Box A $0.416/oz, Box B $0.388/oz — also Box B wins. Servings-based comparison is most relevant for packaged foods where portion size varies between products.