Unit Price Calculator
Compare grocery options by their true cost per unit — per 100 g, per litre, or per item — so you can spot the best value at a glance, even across different pack sizes and discounts.
Calculator
Item 2 wins
20%Item 2 works out to $0.80/100 g per 100 g — 20% cheaper than the priciest option here. Across the same amount, that's the gap between a good deal and an expensive one.
Horizontal bars ranking each option from cheapest to priciest, with each loser's overspend versus the cheapest.
- Item 2$0.80/100 g · best
- Item 1$1.00/100 g · +25% / +$0.20
Bigger packs aren't always cheaper. This compares the real cost per unit so size and on-shelf discounts don't fool you. Item names stay on your device and aren't saved in the link.
About this calculator
The "value" pack is not always the better buy. Shelf prices hide the real cost because every option comes in a different size, and a promotion on the small pack can quietly beat the big one. This calculator puts each option on the same footing — cost per 100 g, per litre, or per item — so the best value is obvious. Better still, tell it how much you actually need and it works out the cheapest way to buy that amount, then shows exactly how much every other pack overspends, in both percent and money. Punch in the price and size of each option (add a discount if one is on offer) right there in the aisle and let the numbers decide.
How to read your results
Pick what you are comparing at the top — weight, volume, or count — then add a row for each option with its price, pack size, and unit. Leave the "How much do you actually need?" box blank to simply compare the cost per unit; fill it in to switch the result into bulk-buy mode. In bulk-buy mode the headline becomes the cheapest total cost to get the amount you need, and the compare chart ranks every option from cheapest to priciest with each loser's overspend (+%, +money) versus the winner. Either way the winning row is marked with a chip and every row shows its own unit price, so even the options that did not win are easy to read off.
How it's calculated
Each option is converted to a common base unit before comparing. Weight units convert to grams (g ×1, kg ×1000, oz ×28.349523125, lb ×453.59237); volume units convert to millilitres (ml ×1, L ×1000, fl oz ×29.5735295625); count uses each (×1). The price is first reduced by any discount: effective price = price × (1 − discount% ÷ 100). The cost per base unit is the effective price ÷ size-in-base, which is then scaled to a friendly figure: per 100 g for weight, per litre for volume, per item for count. The option with the lowest scaled unit price is the best value; "cheaper than priciest" is (most expensive − cheapest) ÷ most expensive, as a percentage. When you enter a target amount, each option's cost-for-target is its per-base price × the target converted to the same base; the cheapest cost-for-target wins, and every other option's overspend is (its cost − the cheapest cost) ÷ the cheapest cost. Item names stay in your browser for the session and are never stored or put in a shared link — the link records each option's price, size, unit, and discount (plus any target amount) so the comparison reproduces exactly.
Worked example
Comparing by weight: a 500 g jar of coffee at $5.00, and a 1 kg jar at $8.00 with no discount. You need 750 g.
Per unit, the 500 g jar is $1.00 per 100 g and the 1 kg jar is $0.80 per 100 g — the big jar is 20% cheaper. For the 750 g you need, the 1 kg jar costs $6.00 while buying enough of the 500 g jars costs $7.50 — so the small pack overspends by $1.50, or +25%. The big jar wins, even though its sticker price is higher.
Frequently asked questions
How much do I actually save buying in bulk?
Enter how much you need in the "How much do you actually need?" box and the calculator works out the cheapest total cost to get that amount, then shows how much each other pack overspends in both money and percent. Bulk is not always cheaper — a smaller pack on promotion can beat the big one for the quantity you need — so this tells you the real saving for your situation rather than assuming the biggest pack wins. For example, needing 750 g of coffee, a $8 / 1 kg jar costs $6.00 while the equivalent in $5 / 500 g jars costs $7.50, a 25% ($1.50) saving for the bigger jar.
Why is the bigger pack sometimes not the better deal?
Stores often price larger packs to feel like a saving, but the cost per 100 g, per litre, or per item can be the same or even higher than a smaller pack — particularly when the smaller size is on promotion. Comparing the unit price removes the pack-size illusion so you can see the real cost and buy the genuinely cheaper option.
How do I handle an item that is on offer?
Use the discount field. Enter the percentage off and the calculator lowers that option's price before working out its unit price. For example, a 1 kg pack at $10 with 20% off is compared at its effective $8 — which lets you check whether the discounted big pack actually beats a smaller pack at full price, rather than just assuming it does.
Can I compare weight against volume, or items against grams?
No, and that is deliberate. A unit price only means something when every option shares the same base unit, so each comparison uses one measure type — weight, volume, or count. Switch the measure at the top and every row adopts that family's units. Comparing a 500 g jar to a 500 ml bottle would not give a meaningful "better value" answer.
Is the unit price a guaranteed price?
No. It is arithmetic on the price and size you type in, meant to help you compare options quickly on the shelf. Always check the store's own unit-price label too, since drained weights, pack contents, and promotions vary by store and change over time.
Sources
Reviewed by the YouCalc Team · Last reviewed
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