Unit Price Comparison Calculator
Compare packages of different sizes and units by price per unit, including multi-buys, to see which is actually cheaper.
Result
Cheapest option: Box
Compares price per unit only. Whether the larger pack gets used before it spoils is not something arithmetic can answer.
- Price per unit
- Box: 4.5704, Bag: 4.8355
- Saving against the next cheapest
- 5.48%
https://calcgallery.com/shopping/unit-price-comparison-calculator/
Results are arithmetic from the amounts and rates you enter. The site publishes no tax rate, threshold or tipping convention, and rates vary by jurisdiction and change. Check the rate on your receipt, invoice or tax authority guidance, and confirm anything that matters with a qualified adviser. Read the full disclaimer
How to use the Unit Price Comparison Calculator
- Add a row for each package, with its price and how much is in it.
- Enter the unit each quantity is measured in — they can differ between rows.
- Use the offer column for a multi-buy, so "3 for 10" is three units at ten.
- Read the price per unit for each, and which is cheapest.
How it is calculated
effective quantity = quantity × offer countunit price = price ÷ effective quantityEverything is converted to one SI base first — kilograms for mass, litres for volume, metres for length, or a plain count — so packages labelled in different units can sit in the same list.
The answer does not depend on the unit you typed. A 24 oz bag and a 680.4 g bag are the same package and get the same price per kilogram. That invariance is tested.
Worked comparisons
| A | B | Cheaper |
|---|---|---|
| 1.42 kg box at 6.49 | 24 oz bag at 3.29 | A, 4.57/kg against 4.84/kg |
| 2 L at 3.00 | 1 US gallon at 5.50 | B, 1.45/L against 1.50/L |
| 500 g at 2.00 | 1 kg at 3.80 | B, 3.80/kg against 4.00/kg |
| 12 items at 6.00 | 3 for 1.60 | A, 0.50 each against 0.53 |
The gallon case is the one worth noticing: the bigger container is cheaper per litre, but only by 3%, which is not what the size difference suggests.
When the comparison is refused
A mass against a volume has no common basis. A litre of one product and a kilogram of another are simply different quantities, and converting between them needs a density the page does not have and should not guess.
When the rows do not share a dimension, the page says so and still reports each unit price, so you can see the figures without being given a winner that would not mean anything.
Practical tips
Shelf labels are not always comparable. Shops sometimes quote per 100 g on one item and per kilogram on another, which is exactly the confusion this page removes.
Multi-buys are often worse than they look. Put the offer in and compare it against the plain pack; “3 for 10” against 3.20 each is a saving of about 4%.
The bigger pack usually wins on unit price, and not always by much. Whether that justifies buying it is a different question.
Waste turns a good unit price into a bad one. Half a large pack thrown away doubles the effective cost of what you used.
With your numbers
- Priced per unit: Box: 4.5704, Bag: 4.8355
- That is 5.48% cheaper than the next best
- The cheapest is Box
Quick reference
Compares price per unit only. Whether the larger pack gets used before it spoils is not something arithmetic can answer.
| Example | Cheapest option |
|---|---|
| 1.42 kg box against a 24 oz bag | Box |
| 2 L against 1 US gallon | Jug |
| 12 items against 3 for 1.60 | Dozen |
| A kilogram against a litre | |
| 500 g against 1 kg | Large |
| Three packs in a multi-buy | Three for 6 |
| Three sizes at once | Large |
| 750 ml against 1 L | Big |
Common questions about the Unit Price Comparison Calculator
- Can I compare a package in ounces with one in kilograms?
- Yes. Every quantity is converted to one common base before the comparison, so a 24 oz bag and a 1.42 kg box are priced against each other directly. The answer does not depend on which unit you typed; entering the same package in grams or in ounces gives the same price per kilogram.
- Why will it not compare a kilogram with a litre?
- Because there is no conversion between them that holds for all products. A litre of oil and a litre of syrup weigh different amounts, so a price per litre and a price per kilogram are not comparable without knowing the density. Rather than invent a conversion, the page reports the mismatch and still shows each unit price.
- How do multi-buy offers work?
- The offer column multiplies the quantity. "3 for 10" is a quantity of one pack with an offer count of three, or equivalently the total across three packs — either way the page divides the price by the total quantity you receive. That is what makes a multi-buy comparable against a single large pack.
- Is the cheapest per unit always the best buy?
- No, and the page only answers the arithmetic. A larger pack is cheaper per unit and worse value if half of it spoils before you use it, or if you do not have the space, or if the cash matters now. Unit price is one input to the decision rather than the decision.
- What does `each` mean?
- A plain count, for things sold by the item rather than by weight or volume. Twelve items at 6.00 is 0.50 each. A count is its own kind of unit, so the page will not compare a per-item price against a per-kilogram one, for the same reason it will not compare mass with volume.