Shops price the same product in different units to make comparison hard. Convert any price to a common unit — per kilogram, per 100 g, per litre, per 100 ml or per single item — so you can compare two options fairly and see which is really cheaper.
Option A
Option B
Better value
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Compare like with like (mass vs mass, volume vs volume). Calculations run in your browser.
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Why shops price things in different units
One brand sells coffee per 500 g, another per kilogram; one juice is priced per litre, a rival per 100 ml. These mismatched units make it hard to tell at a glance which is cheaper — sometimes deliberately. Converting both to a single common unit (per kg, per litre or per item) is the only way to compare fairly, and that's exactly what this converter does in one step.
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How to compare like with like
You can only compare prices within the same measurement family: mass with mass, volume with volume, or count with count. You can't directly compare per-kilogram against per-litre, because they measure different things. Pick the matching unit for each option here, and the tool converts both to a shared base (per kg, per litre or per item) so the comparison is valid and the cheaper option is clear.
The bigger pack isn't always cheaper
Larger sizes usually have a lower unit price, but not always — promotions on smaller packs, premium 'travel' sizes and bulk items near their use-by date can flip the maths. Always run the actual numbers rather than assuming bigger is better. Once you see the per-unit price for each option side by side, the genuinely cheaper choice is obvious, regardless of pack size.
Frequently asked questions
How do I compare prices with different units?
Convert both products to the same common unit before comparing. For mass, work out the price per kilogram (or per 100 g); for liquids, the price per litre (or per 100 ml); for items, the price each. This converter does it automatically — just enter each option's price, quantity and unit, and it shows the cheaper one in a shared unit.
Can I compare price per kg against price per litre?
No — mass and volume measure different things, so a per-kilogram price can't be directly compared with a per-litre price. You can only compare within the same family: mass with mass, volume with volume, or items with items. The calculator enforces this and will prompt you if you mix unit types, so your comparison stays valid.
Is the larger size always better value?
Usually it has a lower unit price, but not always. Special offers on smaller packs, premium small 'convenience' sizes, and clearance deals can make a smaller option cheaper per unit. The only reliable way to know is to calculate the price per common unit for each, which this tool does instantly so you can buy on real value, not pack size.
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