Price per 100 g calculator
Enter the price and the weight, and you get the price per 100 g and per kilogram — the fastest way to compare packs that come in different sizes.
Your numbers
Use the amount you actually pay, after discounts.
Copy the weight printed on the packaging.
For multi-packs, enter how many packs you get.
Weight unit
Result
Enter your numbers and the result appears here.
How this is calculated
- The price is divided by the total weight to get a price per gram, then multiplied by 100.
- Choosing kilograms converts the weight at 1 kg = 1,000 g before the calculation.
- Setting a quantity above one uses the total weight (weight per pack x quantity), so multi-packs work too.
- For an accurate figure, enter what you actually pay after any discount rather than the shelf price.
- Everything is calculated in your browser; nothing is sent to a server or stored.
Formula
- Total weight
total weight (g) = weight per pack x quantity (x 1,000 if entered in kg)- Price per 100 g
price per 100 g = price / total weight (g) x 100Use the amount you actually pay, including any discount.
- Price per kilogram
price per kg = price per 100 g x 10
Worked example
A 400 g jar of coffee costs $18.00; a 1 kg bag of the same coffee costs $39.00.
- 400 g jar: 18.00 / 400 = $0.045 per gram, so $4.50 per 100 g
- 1 kg bag: 39.00 / 1,000 = $0.039 per gram, so $3.90 per 100 g
- Difference: $0.60 per 100 g, about 13% cheaper for the bag
The 1 kg bag is about 13% cheaper per 100 g. That only holds if the coffee stays fresh long enough for you to finish it.
Things to watch for
- Packaging weight and drained weight are not the same thing. Tinned goods often list both a total weight and a drained weight — compare like with like.
- Dried and frozen products change weight when prepared, so price per 100 g alone will not tell you which is better value for a meal.
- A lower unit price is only a saving if the product gets used before it spoils.
- For online orders, add delivery to the price before calculating, otherwise the unit price is understated.
Frequently asked questions
Why compare per 100 g rather than per pack?
Pack sizes differ, so shelf prices are not comparable on their own. Converting to a common 100 g basis puts a 300 g pack and a 1.2 kg pack on the same scale — the same logic supermarket unit-price labels use.
Which price should I enter if I have a discount code?
Enter the amount you actually pay after the code and any card discount. Using the shelf price makes the unit price look higher than it really is.
How do I handle a buy-one-get-one offer?
Enter the price you pay and the number of packs you receive. For buy one get one free, that is the price of one pack with a quantity of two.
Is the cheapest price per 100 g always the best buy?
No. Storage space, shelf life and how quickly you use the product matter. Throwing half of a large pack away costs more than paying a little extra for a smaller one.
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Last reviewed: August 25, 2026
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