This free unit price calculator compares up to four products by cost per unit so you can see which one is genuinely the best value, not just the cheapest sticker price. Enter each pack’s price and size in any unit — grams, ounces, litres, or count — and it normalizes everything to a common cost per 100g, per 100ml, or per item. It works in any currency and settles the “is the big pack actually cheaper?” question in seconds. No signup required.
Add each product’s price and pack size to see the cost per unit and which option is the best value.
Compared the shelf, now track what you actually spend. Auritrack logs your grocery receipts and shows where your money goes each month.
Try Auritrack FreeType the price you pay for the first product and its pack size (for example, 3.99 for 500 grams). Give it an optional name like "Store brand" so the results are easy to read.
Add a second product, and up to four in total, entering the price and size of each. These are the packs sitting next to each other on the shelf that you want to compare.
Choose the unit each size is measured in (grams, kilograms, ounces, pounds, millilitres, litres, or each/count). You can mix units within the same type, such as grams and ounces.
Select your currency from the selector in the top right. The calculator works in any currency and remembers your choice for next time.
Instantly see the cost per 100g, per 100ml, or per item for every product, ranked cheapest first. The best value is highlighted, along with how much cheaper it is than the next option.
The sticker price on a shelf tells you what leaves your wallet, but it says nothing about value. To compare value you need the unit price: the cost of one standardized measure, such as 100 grams, one litre, or a single item. The method is simple. Divide the pack price by its size, then multiply so every product is expressed on the same basis. A 500g jar at $3.99 is $0.80 per 100g, while a 750g jar at $5.49 is $0.73 per 100g. The larger jar wins by 9 percent, even though it costs more at the register. Doing this by hand at the shelf is slow and error-prone, especially when pack sizes are awkward numbers like 340g or 1.36kg. That is exactly what this calculator removes: enter the numbers as printed on the label and it puts every option on a level footing instantly.
There is a widespread assumption that buying the larger size always saves money. It usually does, but retailers know shoppers believe this, and they sometimes price the family size at a higher cost per unit than the medium one. The phenomenon even has a name among consumer advocates: the “bulk penalty.” It shows up most often on promoted products, where a smaller pack on a multi-buy deal quietly beats the giant tub sitting next to it. The only way to catch this is to check the cost per unit every time rather than trusting the pack size. A larger pack is also only a saving if you use the product before it goes off. Cheaper yoghurt per 100g is no bargain if half of it ends up in the bin. Match the size to what you will realistically get through, then let the unit price decide between the sizes you would actually finish. If a promotion is in play, our discount calculator helps you work out the true post-discount price before you compare.
A fair comparison only works when you compare the same kind of measure. Weight (grams, kilograms, ounces, pounds), volume (millilitres, litres), and count (each, per item) are three separate families, and mixing them produces meaningless results. You cannot sensibly say that 100 grams of pasta is cheaper or dearer than 100 millilitres of olive oil, because the two are measured on different scales. This calculator ranks products only within a single family and flags it clearly when your entries span more than one. Within a family you can freely mix units: it converts ounces to grams and litres to millilitres for you, so a pack sold in pounds compares cleanly against one sold in grams. When you genuinely need to compare across families, the honest approach is to compare per serving or per finished dish rather than per weight, since that is what you actually consume.
Comparing unit price is one of the highest-return habits in everyday budgeting because you apply it dozens of times on a single shop. The savings on any one item are small, but they compound across every staple you buy week after week. Store brands are the clearest example: they frequently carry a materially lower cost per unit than the name-brand product sitting beside them, often for an identical or near-identical product. Multi-buy and loyalty prices are worth recomputing rather than assuming, because “3 for $5” is not always better than the single-unit price once you do the arithmetic. The goal is not to obsess over every cent but to make the cheaper choice the default on the items you buy repeatedly. To see how those shelf-level wins add up across a whole month, plan your spending with our budget planner, and if you shop or travel across borders, our currency converter lets you compare prices priced in different currencies on the same terms.
Most supermarkets are required to print a unit price on the shelf label, but the way it is displayed is not always designed to help you. A common tactic is inconsistent units: one brand is priced per 100g and the identical product next to it is priced per kg or per ounce, so the two numbers cannot be eyeballed side by side. Some labels quote the unit price in tiny type while the pack price and any “SALE” flash dominate the sign. Round-number packaging, such as 900g instead of a full kilogram, makes mental math harder and the per-unit figure less obvious. Promotional signage adds another layer, framing a multi-buy as a saving without stating the resulting cost per unit at all.
The defence is the same every time: ignore the sticker price and the sale flash, find the cost per unit, and if the store quotes two products in different units, convert them yourself. That is where a quick check on your phone pays off. Enter the two prices and sizes exactly as printed, and this calculator puts them on a single, comparable basis so the genuine best value is obvious, whatever the label is doing to disguise it. Over a year of weekly shops, consistently picking the lower unit price on your regular staples is one of the least painful ways to trim a grocery budget without giving anything up.
See the sale price and how much you save on any discount. Stack multiple discounts and add sales tax to get the true final price.
Describe your situation and let AI build a personalized monthly budget instantly. Or do it yourself with the 50/30/20 rule, custom ratios, or zero-based budgeting.
Convert any amount between 150+ currencies with live exchange rates. Fast, accurate, and always up to date.
Shop Smarter
Comparing the shelf is step one. Auritrack logs your receipts, tracks your grocery spending in real time, and shows where your money goes each month, in any currency. Free to start.
Disclaimer: This tool is provided for informational and educational purposes only. It does not constitute financial, tax, investment, or legal advice. Results are estimates based on the inputs you provide and may not reflect actual financial outcomes. Always consult a qualified financial professional before making financial decisions.
