ClutchCalcs

Math

Price Per Unit Calculator

The bigger package isn't always cheaper. Manufacturers play games with package sizes specifically so the unit price math is harder to do in your head: 18 oz at $5.99 vs 32 oz at $8.99 — which one's actually the deal? (The 32 oz wins, at $0.281/oz vs $0.333/oz — about 16% cheaper per ounce.) This calculator takes two products' prices and quantities, returns price-per-unit for each, declares which is better, and shows the % savings. Use for groceries, supplements, batteries, paint, packaged anything — the unit you compare has to match (both in oz, both in ct, etc.) but the math works regardless.

Better deal

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Item 1 per unit
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Item 2 per unit
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% savings
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How shelf unit prices can fool you

Many stores now print unit price on the shelf tag, which is great — except they're inconsistent about the unit. The same store might list:

  • Cereal: price per ounce
  • Milk: price per pint (not per ounce)
  • Eggs: price per dozen
  • Soft drinks: price per 100 ml on the big bottle, price per ounce on the can next to it
  • Detergent: price per load (calculated from manufacturer's listed dose)

When the units don't match, the shelf tags don't help comparison. Bring your own price-per-ounce or price-per-load math — or this calculator — to actually compare.

When bulk WINS

  • Shelf-stable staples you use weekly: rice, pasta, oats, beans, cooking oil, flour, sugar. The 25-lb bag is almost always cheaper per pound and stores fine.
  • Costco-style warehouse on basics: toilet paper, paper towels, laundry pods, dish soap. Per-unit savings often 30-50%.
  • Generic / store-brand bulk: often outright cheaper than the name-brand in any size.

When bulk LOSES

  • Perishable items you can't finish: a 5-lb tub of yogurt that goes bad isn't a deal at any price.
  • Items that go stale fast: bulk chips, crackers, cereal in households of 1-2 people.
  • Specialty / occasional-use items: a 1-gallon vinegar bottle you'll use 1/8 of before forgetting.
  • "Family-size" gimmicks: sometimes the bigger box is actually more per ounce. Always check unit price; don't assume.

How to use this calculator

  1. Item 1 price + quantity: enter both in matching units (e.g., $5.99 / 16 oz).
  2. Item 2 price + quantity: same units as item 1.
  3. Output: which item is the better deal, price per unit for each, and % savings.
  4. For multi-pack vs single: total cost ÷ total count. Compare apples to apples (units must match — if one is in oz and one is in ml, convert first).

Common scenarios

Olive oil: 17 oz at $9.99 vs 33.8 oz at $16.99. Item 1 = $0.588/oz. Item 2 = $0.502/oz. Item 2 is 14.6% cheaper per ounce. Bigger bottle wins.

Toilet paper: 12 mega rolls at $14.99 vs 30 regular rolls at $14.99. Without knowing rolls' actual sheet count, this is incomplete. Mega rolls vary 300-450 sheets each; regular rolls 150-225 sheets. Convert to per-sheet for actual comparison: 12 × 400 = 4,800 sheets vs 30 × 200 = 6,000 sheets. Same price = regular wins per sheet.

Greek yogurt: 5.3 oz cup at $1.29 vs 32 oz tub at $5.99. Cup: $0.243/oz. Tub: $0.187/oz. Tub is 23% cheaper per ounce — IF you'll use it before the expiration date. For a family of 4 eating yogurt regularly, tub wins. For a single person who uses yogurt once a week, the cups don't go bad.

FAQ

What's the right unit to compare? +
The smallest meaningful unit for the product. Liquids: oz or ml. Solids: oz or g. Items: each, dozen, pack of 10. Detergent: load (use manufacturer's listed dose count). Paper goods: sheets if comparable, otherwise rolls of like type.
How do I handle different units — oz vs ml, lb vs kg? +
Convert one to match the other. 1 oz = ~29.6 ml. 1 lb = 16 oz = 454 g. 1 gallon = 128 oz = 3.785 L. Convert the smaller one to match the larger so the math is cleaner.
Does "price per use" sometimes matter more than "price per oz"? +
For products with concentration differences (laundry detergent, dish soap, fabric softener), yes. A concentrated formula uses less per load; "price per load" is a better comparison than "price per oz." Many detergent brands now print "loads per bottle" prominently.
What about per-ounce on canned goods with water? +
Read the drained weight on the label. A 15-oz can of beans labeled "15 oz" might have only 8 oz of beans + 7 oz of water. Compare drained weights, not total can weights. Same applies to canned tuna, vegetables, fruit.
Are big-box club stores actually cheaper? +
For non-perishables and predictable household consumption: usually 20-40% cheaper per unit than supermarkets. Subtract the membership fee ($50-110/year) divided by your annual purchases. Pays off for households spending $50+ per visit. Less worth it for single people in small apartments.
What about "sale price" timing? +
Most grocery items go on sale in a roughly 8-12 week cycle. If you know an item's lowest sale price, only stock up when it hits that price. Calculator's unit-price logic still applies — compare the sale price unit-rate to other sources.
Should I factor in time or driving? +
For most households: yes — driving 15 minutes extra to save $1.50 isn't a win. Stick to stores on your normal route. Online price comparison (Amazon vs grocery delivery vs warehouse) skips the driving variable entirely.
How do you spot shrinkflation? +
Compare your current package size to the same product 1-2 years ago. Famous examples: cereal boxes have shrunk from 18 oz to 12 oz at the same price; toilet paper rolls from 500 sheets to 350. The product is the same; the price-per-unit jumped 30-40% silently.