Unit Price Calculator: Which Is the Better Deal?

Enter the price and size of up to four products to see each one's price per unit, which is cheapest, and how much more the others cost.

Runs in your browserFree, no sign-upLast reviewed October 13, 2026

Settings

Item 1 price

Item 1 quantity in the pack

How many units the price buys, such as 6 for a six-pack. Leave at 1 for a single item.

Item 1 size of each unit

The weight, volume or length of one unit. Enter 1 when comparing by count.

Item 1 unit

Item 2 price

Item 2 quantity in the pack

Item 2 size of each unit

Item 2 unit

Item 3 price (optional)

Item 3 quantity in the pack

Item 3 size of each unit

Item 3 unit

Item 4 price (optional)

Item 4 quantity in the pack

Item 4 size of each unit

Item 4 unit

Show unit price per

Results update automatically as you type.

Best value

Cheapest per unit: Item 2
Lowest price per 100 g: 0.599
Highest price per 100 g: 0.698
Cheapest vs dearest: 14.18% less; per unit

Price per 100 g

Item	Price	Contents	Price per 100 g	Compared with cheapest	Extra paid at this price
Item 1	3.49	500 g	0.698	+16.53%	0.49
Item 2	5.99	1 kg	0.599	Cheapest	—

The same unit prices in other units

Item	Per 100 g	Per kg	Per oz	Per lb
Item 1	0.698	6.98	0.1979	3.1661
Item 2	0.599	5.99	0.1698	2.717

Item 2 is the better deal. Item 1 costs 16.53% more per 100 g (0.698 against 0.599). Buying Item 1's contents at the cheapest rate would cost 3.00 instead of 3.49.

Summary

Item 1: 3.49 for 500 g = 0.698 per 100 g Item 2: 5.99 for 1 kg = 0.599 per 100 g (cheapest)

Quick answers

How do I calculate unit price?: Divide the price by the quantity. A 12 oz jar for 3.99 costs 3.99 ÷ 12 = 0.3325 per oz. For a multipack, multiply the count by the size first: six 330 ml cans for 4.50 hold 1,980 ml, which is 0.2273 per 100 ml.
How do I work out which product is the better deal?: Work out the price per unit for each one in the same unit, then pick the lowest. 18 oz for 2.89 is 0.1606 per oz and 30 oz for 4.19 is 0.1397 per oz, so the 30 oz pack is cheaper per ounce by 13.01%.
How do I calculate price per 100 g?: Divide the price by the weight in grams and multiply by 100. A 400 g pack for 1.20 costs 1.20 ÷ 400 × 100 = 0.30 per 100 g. A 1 kg pack for 2.75 costs 0.275 per 100 g.
Is the bigger pack always cheaper per unit?: No. Larger packs often cost less per unit, but not always, and promotions on small packs can reverse it. The only reliable check is to compare the unit prices. A lower unit price also only saves money if you use all of what you buy.
Can I compare ounces with grams or pounds with kilograms?: Yes. Weights are converted using 1 oz = 28.349523125 g and 1 lb = 453.59237 g, so a 12 oz jar, a 1 lb bag and a 200 g pouch can be ranked together. You cannot compare a weight with a volume, because that depends on the product's density.
How do I find the price per item in a multipack?: Divide the pack price by the number of items. A 12-pack for 6.99 is 0.5825 per item and a 24-pack for 10.49 is 0.4371 per item. In the calculator, enter the count as the quantity, 1 as the size and choose each as the unit.

How Unit Price Calculator works

Unit price is the price divided by how much you get. A 500 g pack for 3.49 costs 0.698 per 100 g; a 1 kg pack for 5.99 costs 0.599 per 100 g, so the larger pack is the better deal and the smaller one costs 16.53% more for the same amount. This unit price calculator compares up to four products at once and converts between units for you, so a pack in grams can be set against one in pounds, or millilitres against US fluid ounces. It marks the cheapest, shows the percent difference for the rest, and restates every unit price per 100 g, kg, oz and lb or the volume equivalents.

Worked unit price comparisons

Two pack sizes of the same product, grams against kilograms

Item 1: price 3.49, quantity 1, size 500 g. Item 2: price 5.99, quantity 1, size 1 kg

Item 2 is cheapest at 0.599 per 100 g. Item 1 is 0.698 per 100 g, +16.53%, an extra 0.49 for its 500 g. Cheapest vs dearest: 14.18% less

The same prices per kg are 6.98 and 5.99; per lb they are 3.1661 and 2.717.

Cans, a large bottle and a small bottle

Item 1: price 4.50, quantity 6, size 330 ml. Item 2: price 2.19, quantity 1, size 2 L. Item 3: price 1.05, quantity 1, size 500 ml

Item 2 is cheapest at 0.1095 per 100 ml. Item 1 is 0.2273 per 100 ml (+107.56%) and Item 3 is 0.21 per 100 ml (+91.78%)

The six-pack's 1,980 ml would cost 2.17 at the 2 L bottle's rate, so it carries 2.33 extra.

Four packs in ounces, pounds and grams

Item 1: 3.99 for 12 oz. Item 2: 5.49 for 1 lb. Item 3: 8.99 for 2 lb. Item 4: 2.50 for 200 g

Item 3 is cheapest at 0.2809 per oz. Item 1 is 0.3325 per oz (+18.35%), Item 2 is 0.3431 per oz (+22.14%) and Item 4 is 0.3544 per oz (+26.14%)

Rolls with different sheet counts

Item 1: price 7.99, quantity 9, size 200, unit each. Item 2: price 5.49, quantity 6, size 220, unit each

Item 2 is cheapest at 0.004159 per item (1,320 sheets). Item 1 is 0.004439 per item (1,800 sheets), +6.73%, an extra 0.50

Putting sheets per roll in the size box compares price per sheet rather than price per roll.

A US gallon against a 32 fl oz bottle, shown per litre

Item 1: 3.79 for 1 US gal. Item 2: 1.29 for 32 US fl oz. Show unit price per: litre

Item 1 is cheapest at 1.0012 per litre. Item 2 is 1.3631 per litre, +36.15%

Unit price formula and how the percent difference is worked out

Total contents = Quantity in the pack × Size of each unit Unit price = Price ÷ Total contents Compared with cheapest % = (Unit price ÷ Lowest unit price − 1) × 100 Extra paid = Price − Lowest unit price × Total contents Cheapest vs dearest % = (1 − Lowest unit price ÷ Highest unit price) × 100

Before dividing, every size is converted to one base unit: grams for weight, millilitres for volume, metres for length. The two percentages answer different questions and are not the same number. In the first example the smaller pack costs 16.53% more than the cheapest, while the cheapest costs 14.18% less than the smaller pack. Extra paid is in money: what you pay above the cheapest rate for the amount that pack contains.

Price per 100 g to price per kg, oz and lb

The same unit price written the four ways the calculator shows it. Useful when one label quotes per 100 g and another per ounce or pound.

Per 100 g	Per kg	Per oz	Per lb
0.25	2.50	0.0709	1.134
0.50	5.00	0.1417	2.268
0.75	7.50	0.2126	3.4019
1.00	10.00	0.2835	4.5359
1.25	12.50	0.3544	5.6699
1.50	15.00	0.4252	6.8039
2.00	20.00	0.567	9.0718
2.50	25.00	0.7087	11.3398
3.00	30.00	0.8505	13.6078
5.00	50.00	1.4175	22.6796

Price per ounce to price per pound, 100 g and kg

Per oz	Per lb	Per 100 g	Per kg
0.10	1.60	0.3527	3.5274
0.15	2.40	0.5291	5.2911
0.20	3.20	0.7055	7.0548
0.25	4.00	0.8818	8.8185
0.30	4.80	1.0582	10.5822
0.40	6.40	1.411	14.1096
0.50	8.00	1.7637	17.637
0.75	12.00	2.6455	26.4555
1.00	16.00	3.5274	35.274

A pound is exactly 16 ounces, so the per lb figure is always 16 times the per oz figure.

Price per 100 ml to price per litre, US fluid ounce and US gallon

Per 100 ml	Per litre	Per US fl oz	Per US gal
0.05	0.50	0.0148	1.8927
0.10	1.00	0.0296	3.7854
0.15	1.50	0.0444	5.6781
0.20	2.00	0.0591	7.5708
0.25	2.50	0.0739	9.4635
0.50	5.00	0.1479	18.9271
0.75	7.50	0.2218	28.3906
1.00	10.00	0.2957	37.8541
2.00	20.00	0.5915	75.7082

Volume conversions use US customary sizes: 1 US fl oz = 29.5735295625 ml and 1 US gal = 3,785.411784 ml. UK imperial fluid ounces and gallons are different sizes and are not offered; enter UK products in ml or litres.

What the calculator does not account for

Quality, concentration and waste. A concentrated detergent or a product you will not finish before it spoils can be worse value at a lower unit price.
Weight against volume. Grams cannot be compared with millilitres, so every item must use the same kind of unit. Mixing them returns an error naming the two items.
UK imperial fluid ounces, pints and gallons. Only US fluid ounces and US gallons are available for volume.
Tax, deposits, delivery charges, loyalty prices and coupons, unless you include them in the price you type.
Product names. Items are labelled Item 1 to Item 4, so note which is which.
Currency. Prices are plain numbers with no symbol, and all items are assumed to be in the same currency.

Using Unit Price Calculator

1
For Item 1, enter the price, then the quantity in the pack: 1 for a single item, 6 for a six-pack.
2
Enter the size of each unit and choose its unit: weight (g, kg, oz, lb), volume (ml, L, US fl oz, US gal), length (m, ft, yd) or each for a plain count.
3
Do the same for Item 2, and for Item 3 and Item 4 if you have them. Leave the price and size of an unused item blank.
4
Leave Show unit price per on Automatic, or pick the unit you want every price expressed in, such as 100 g, oz or litre.
5
Read the Best value box, then the table showing each item's unit price, how far it is above the cheapest and the extra paid at that price.

Common questions

What is a unit price?

It is the cost of one standard measure of a product, such as one ounce, 100 grams, one litre or one item. Shops often print it in small type on the shelf label. It lets you compare packs of different sizes on equal terms.

What do I enter for quantity and size?

Quantity is how many units the price buys, and size is how big each unit is. Six 330 ml cans are quantity 6 and size 330 ml. One 2 L bottle is quantity 1 and size 2 L. The two are multiplied to get the total contents.

Which unit does the result use?

On Automatic, it follows Item 1: grams give a price per 100 g, millilitres a price per 100 ml, and kg, oz, lb, L, US fl oz, US gal, m, ft and yd a price per one of that unit. Change Show unit price per to override it. A second table lists the other units of the same kind.

Why are some unit prices shown with four or six decimals?

Unit prices are often fractions of the smallest coin, and rounding them to two decimals would hide real differences. Prices under 100 are shown with up to four decimals, and prices under 0.01, such as a price per sheet, with up to six. Amounts of money, like the extra paid, are rounded to two.

What does Extra paid at this price mean?

It is how much more that pack costs than the same amount would at the cheapest unit price. For a 500 g pack at 3.49 against a rate of 0.599 per 100 g, the 500 g would cost 3.00, so the extra is 0.49.

Can I use it for things that are not groceries?

Yes. It works for anything sold by weight, volume, length or count: paint by the litre, cable or fabric by the metre or yard, screws or tablets by count. Length units are metres, feet and yards.

What happens if two items have the same unit price?

They are both marked as cheapest and the Best value box reports a tie. If every item has the same unit price, the result says there is no difference and each row is marked Same.

How is this different from a discount calculator?

A discount calculator takes a percentage off one price. This page compares several products by what you get for the money. To compare a discounted item, work out its sale price first and enter that as the price here.