Price Per 100g Calculator
Comparing grocery prices across pack sizes is much easier when everything is reduced to a single standard amount, and 100 grams is the common reference on unit-price labels and nutrition panels. This calculator finds the price per 100 grams by dividing the total price by the weight in grams to get the price per gram, then scaling up to 100 grams. The result lets you line up two products of different sizes and see which truly costs less for the same quantity. Enter the price and the gram weight for one item, then repeat for a competitor, and compare directly. The weight is printed on the package as the net weight, and the calculator handles the scaling. A price per 100 grams cannot be compared straight to a price per ounce, since an ounce is about 28.35 grams, so keep both items in the same unit. The lowest price per 100 grams is normally the better buy, but only if you will use the whole pack before it spoils. Every figure here is computed deterministically from the standard unit-price formula, shown in full below, with a worked example that reconciles exactly to the calculator so you can follow each step.
Price per 100 grams is the price divided by the weight in hundreds of grams: per 100g = price / (grams / 100). A $6.50 pack of 500 grams costs $1.30 per 100 grams.
Price per 100g formula
Price per 100g = price / (grams / 100)
price = total shelf price ($)
grams = net weight (g)
Equivalently: (price / grams) x 100
Dividing the price by the weight in hundreds of grams gives a unit price tied to a standard 100 gram amount, comparable across pack sizes.
Worked example
A pack priced at 6.50 dollars weighing 500 grams.
- Hundreds of grams = 500 / 100 = 5
- Divide the price: 6.50 / 5 = 1.30
- Price per 100g = $1.30
The unit price is 1.30 dollars per 100 grams. These are the calculator's default inputs, so the result above matches the widget exactly.
Price per 100g for a 6.50 dollar pack
A heavier pack at the same price has a lower price per 100 grams.
| Weight (g) | Price per 100g |
|---|---|
| 250 | $2.60 |
| 500 | $1.30 |
| 650 | $1.00 |
| 1,000 | $0.65 |
Weights, measures and unit-pricing standards: US National Institute of Standards and Technology (NIST).
Price per 100g calculator: frequently asked questions
What is price per 100g?
Price per 100 grams is a unit price: the total price divided by the weight in grams, then scaled to a standard 100 gram amount. It lets you compare products of different pack sizes on the same basis. A 6.50 dollar pack of 500 grams works out at 1.30 dollars per 100 grams.
How is it calculated?
Divide the price by the weight in grams to get the price per gram, then multiply by 100. Equivalently, divide the price by the weight expressed in hundreds of grams. For 6.50 dollars and 500 grams, that is 6.50 divided by 5, which is 1.30 dollars per 100 grams.
Why use 100 grams as the standard?
Per 100 grams is the common unit-pricing standard on many grocery labels outside the United States and on nutrition panels everywhere. Using a fixed 100 gram reference makes prices directly comparable between brands and pack sizes at a glance.
Can I compare this with a price per ounce?
Only after converting to the same unit. One ounce is about 28.35 grams, so a price per ounce is not directly comparable to a price per 100 grams. Convert both to the same basis, or use whichever unit both labels share.
Is the cheapest per 100g always best?
Usually it is the better value, but consider whether you will use the whole pack before it spoils and whether you have storage. For perishable food, a lower price per 100 grams in a large pack is no saving if part of it is wasted.
Official sources
- Weights, measures and unit-pricing standards: US National Institute of Standards and Technology (NIST). As at 25 June 2026.
Reviewed by the CalculatorHub team, edited by James Graham, 25 June 2026. See our methodology. This is general information, not financial, tax, legal or investment advice.