Price Per 100g Calculator
Turn any pack price and size into a price per 100 g and per kilogram (or per 100 mL and per litre), including multipacks and 2-for-1 or 3-for-2 deals, and compare up to three products to see which is the better buy.
How it works
Price per 100 g = price paid ÷ (size × items) × 100 · Price per kg = the same × 1,000 · With an offer, price paid = pack price × (packs you pay for ÷ packs you take): 2 for 1 = 0.5, 3 for 2 = 0.667, 4 for 3 = 0.75, 2nd half price = 0.75, 2nd 70% off = 0.65
Shelf prices come in awkward pack sizes — 350 g here, 500 g there, a 6 × 120 g multipack next to them — which makes comparing value hard. Dividing the price by the total weight gives a price per gram, and multiplying by 100 restates it as a price per 100 g, the unit on most European shelf labels; × 1,000 gives the price per kilogram. Drinks, oils and cleaning products work the same way per 100 mL and per litre. Multi-buy offers change the real price: “buy 3, pay for 2” means each pack costs two thirds of its price, and “2nd item half price” cuts the average to 75%, so the calculator works out the price per 100 g you actually pay — as long as you buy the whole offer. Compare up to three products side by side and the calculator names the cheapest per 100 g, shows how much cheaper it is than the next best, and what a recipe-sized amount costs. If your shop labels in ounces and pounds, switch the size unit to oz or lb and turn on the per-ounce and per-pound prices.
Worked example
A $4.50 pack weighing 350 g costs 4.50 ÷ 350 = $0.01286 per gram: about $1.29 per 100 g, or $12.86 per kilogram. A $6.00 500 g pack is $1.20 per 100 g, so it is 6.7% cheaper per gram. With a “buy 3, pay for 2” offer on the small pack, you pay $3.00 per pack and $0.86 per 100 g, which beats the big pack — if you can use 1,050 g before it goes stale. A 6 × 120 g multipack at $5.40 is 720 g in all: $0.75 per 100 g and $0.90 per item.
Frequently asked questions
Why compare by price per 100 g instead of pack price?
Pack prices hide value because sizes differ. A $4.50 / 350 g pack and a $6.00 / 500 g pack look different, but at $1.29 and $1.20 per 100 g the bigger one is slightly cheaper per gram. Choose Compare 2 or Compare 3 to see this side by side.
How do I convert price per 100 g to price per kilogram?
Multiply by 10, since a kilogram is 1,000 g. $1.29 per 100 g is $12.86 per kg. The calculator shows both, plus the price per ounce and per pound if you turn that on.
How do 3-for-2 and second-item-half-price offers change the price per 100 g?
With 3 for 2 you pay for two packs and take three, so the real price is two thirds of the shelf price. With the 2nd item half price you pay 1.5 prices for two packs, or 75% each. Choose the offer in More options and the calculator applies it — it only counts if you buy the full offer and use it all.
Does it work for liquids?
Yes. Choose Volume and enter the size in mL or L; the results become price per 100 mL and per litre. For water-like liquids 1 mL weighs about 1 g, so a per-100 mL price is directly comparable with a per-100 g one.
Does a lower price per 100 g always mean better value?
For the same product, yes. Across different qualities or brands, weigh the per-100 g price against quality and how much you will actually use before it spoils — food you throw away is not a saving.
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This calculator is for educational purposes. Double-check important results before acting on them.