Bigger packs are not always cheaper, and different pack sizes make comparisons hard. Bringing both prices to the same unit shows the real deal. Many stores print a unit price on the shelf label, but they don’t always use the same unit for every brand.
How to use the Unit Price Calculator
- Compare by
- Option A – size of one item
- Option A – volume of one item
- Option A – number of items
- Option A – price
- Option B – size of one item
- Option B – volume of one item
- Option B – number of items
- Option B – price
Results update as you type, and every field accepts the units shown in its menu.
How it works
Choose how the products are measured, then enter the size, number of items and price for both options.
Tips
- Use the figures from your own bills and product labels – prices and appliance ratings vary widely.
- Look at yearly totals: small daily costs add up and make it easier to compare options.
- Round quantities up to whole packs, rolls or bulbs when you shop.
- Re-check the numbers when prices change; most results scale directly with the unit price.
Common mistakes to avoid
- Confusing watts (power) with watt-hours or kilowatt-hours (energy).
- Comparing prices without bringing them to the same unit first.
- Ignoring one-off costs such as installation, delivery or replacement parts.
Inputs explained
| Field | What to enter |
|---|---|
| Compare by | Choose one: Weight, Volume, Number of items |
| Option A – size of one item | Units: lb, oz, kg, g |
| Option A – volume of one item | Units: L, fl oz, mL, US gal |
| Option A – number of items | A number |
| Option A – price | Amount in your currency |
| Option B – size of one item | Units: lb, oz, kg, g |
| Option B – volume of one item | Units: L, fl oz, mL, US gal |
| Option B – number of items | A number |
| Option B – price | Amount in your currency |
Formula
Unit price = price ÷ (quantity × size per item)Saving = (higher unit price − lower) ÷ higher unit priceWorked example
Inputs — Compare by: Weight; Option A – size of one item: 1 lb; Option A – volume of one item: 1 L; Option A – number of items: 1; Option A – price: $4.99; Option B – size of one item: 3 lb; Option B – volume of one item: 2 L; Option B – number of items: 1; Option B – price: $12.99.
Results — Option A unit price = $4.990 per lb / L / item; Option B unit price = $4.330 per lb / L / item; Better deal = Option B; Saving per unit = 13.2 %.
Frequently asked questions
How do I calculate unit price?
Divide the price by the number of units – $4.99 for 16 oz is $0.31 per oz.
Is the bigger pack always cheaper?
No – promotions and smaller "value" packs are often cheaper per unit.
What if one is in ounces and the other in grams?
Choose any unit for each item; the calculator converts both to the same unit.
What formula does the Unit Price Calculator use?
Unit price = price ÷ (quantity × size per item).