Compare two products by price per unit and find the real bargain. Bigger packs are not always cheaper — check the unit price before you buy. Free, no signup, works with any currency.
Unit price is the cost of one unit of a product — for example, the price per kilogram of rice, per liter of milk, or per piece of soap. Supermarkets print it on shelf labels, but online and market shopping often hide it. This calculator reveals it in seconds.
Why the bigger pack is not always cheaper
Stores price products to move stock, not to be fair. A small pack on promotion can beat a bulk pack's per-unit price. Brands also add a "bulk premium" knowing shoppers assume bigger means cheaper. The only number that tells the truth is the unit price.
How to use this calculator
Enter each product's total price and the quantity in the pack.
Pick the unit (grams, liters, pieces...) so both products use the same one.
The tool shows each unit price and marks the cheaper deal with the savings percentage.
Unit price, explained
What is unit price?
Unit price is the cost of one unit of a product — for example, the price per kilogram, per liter, or per piece. It lets you compare products fairly even when pack sizes differ.
How do I find the cheaper product?
Enter the price and quantity of each product. The calculator divides price by quantity to get the unit price — the product with the lower unit price is the cheaper deal, regardless of pack size.
Why is the bigger pack not always cheaper?
Stores often price smaller packs with a better per-unit deal to clear stock, or add premiums to bulk packs. Always compare the unit price, not the pack price.
Is this unit price calculator free?
Yes. It is 100% free with no signup and works in any country with any currency.
What is shrinkflation?
When a manufacturer quietly reduces the pack size — 500 g becomes 450 g — while keeping the price the same. The shelf price never moves, but the unit price jumps about 11%. Checking unit price is the only reliable way to spot it.
How do I compare products sold in different units?
Convert to a common unit first: 1 kg = 1,000 g, 1 litre = 1,000 ml. Then divide each price by its quantity in that unit. Never compare “price per 100 g” directly against “price per kg” — the kg figure will always look 10× larger.
Does unit price work for non-food items too?
Yes — detergent per ml, paper towels per sheet, trash bags per bag. The method is identical: price ÷ quantity in a consistent unit. It even works for services, like comparing mobile plans by cost per GB.
How unit price comparison works
Unit price = total price ÷ quantity, expressed per gram, per millilitre, per sheet — whatever unit fits. It strips away package sizes and marketing so two products compete on one number: the lower unit price is the cheaper buy, provided the units match. Comparing “per 100 g” against “per kg” without converting is the classic shelf-label trap.
Worked examples
Coffee: a 500 g bag at SAR 18 → 18 ÷ 500 = SAR 0.036/g; a 1 kg bag at SAR 32 → 32 ÷ 1000 = SAR 0.032/g. The bigger bag wins by about 11%. But bigger is not always cheaper: a 250 ml shampoo at SAR 9 → 9 ÷ 250 = SAR 0.036/ml, versus a 400 ml bottle at SAR 16 → 16 ÷ 400 = SAR 0.040/ml — here the smaller bottle is 10% cheaper per ml. Brands count on shoppers assuming bulk always wins; the arithmetic says check every time.
Practical tips and limits
Convert to common units first (1 kg = 1,000 g; 1 L = 1,000 ml) before comparing. Watch shrinkflation: when a pack quietly drops from 500 g to 450 g at the same price, the unit price jumps 11% while the shelf price never moves — unit pricing is the only thing that exposes it. And apply judgment to perishables: the cheapest per-unit milk is no bargain if half of it expires before you finish it.
The bulk-buy break-even, with spoilage
The real bulk question is not “cheaper per unit?” but “cheaper per unit actually consumed?” The formula: effective unit price = price ÷ (quantity × share you will use). A 5 kg rice bag at SAR 30 (SAR 6/kg) of which you will realistically cook 4 kg before it stales: effective price = 30 ÷ 4 = SAR 7.50/kg — suddenly the 2 kg bag at SAR 14 (SAR 7/kg) wins. The break-even rule: bulk wins only if (bulk unit price) < (small unit price) × (share you will use). For non-perishables with storage space (detergent, rice, canned goods), the share is ~100% and bulk almost always wins; for fresh produce, dairy, and bakery, be brutally honest about waste before supersizing.