Unit Price Calculator
What is unit price and why does it matter?
Unit price is the price of a product per standard measurement unit — per kilogram, per litre, per 100 grams, per unit. Comparing unit prices rather than pack prices lets you find genuine value regardless of packaging size. A larger pack is not always cheaper per gram, and bulk buying is not always better value — unit price comparison tells you the truth. See also: the Discount Calculator and the Percentage Calculator.
Unit Price = Total Price ÷ Total Quantity (in standard units)
Example: 500g pack for $3.99 = $0.00798/g = $0.80/100g. 1kg pack for $6.49 = $0.00649/g = $0.65/100g. The 1kg pack is 18.5% cheaper per gram.
Shrinkflation — same price, less product
Shrinkflation is when manufacturers reduce the quantity in a package while keeping the price the same. A product that was 500g for $3.99 becomes 450g for $3.99 — same shelf price, but the unit price has increased by 11%. Unit price calculation immediately exposes shrinkflation that is otherwise invisible to shoppers.
Real-world unit price comparisons: India shopping guide
Unit price comparisons are most valuable when products come in different pack sizes, units, or pricing structures. Here are practical India examples:
| Product | Option A | Option B | Unit price A | Unit price B | Better value |
|---|---|---|---|---|---|
| Atta (wheat flour) | 5 kg at ₹220 | 10 kg at ₹410 | ₹44/kg | ₹41/kg | Option B (bulk saves ₹3/kg) |
| Mobile data | 1.5 GB/day at ₹179/28 days | 2 GB/day at ₹249/28 days | ₹6.40/GB | ₹4.45/GB | Option B (lower cost per GB) |
| Olive oil | 500 ml at ₹380 | 1 litre at ₹700 | ₹760/litre | ₹700/litre | Option B (save ₹60/litre) |
| Coffee pods | 10 pods at ₹450 | 20 pods at ₹850 | ₹45/pod | ₹42.50/pod | Option B (save ₹2.50/pod) |
The unit price comparison only tells half the story: also consider shelf life (bulk flour may go stale), storage space, cash flow (spending more upfront), and quality differences between options before assuming the lower unit price is always the better choice.
Unit price for services and subscriptions
Unit price logic applies beyond physical products. Monthly vs annual subscription comparison:
- Music streaming: ₹119/month (monthly) vs ₹1,099/year (annual). Monthly unit: ₹119. Annual unit: ₹91.6/month. Annual saves ₹327 over 12 months (23% cheaper).
- Gym membership: ₹2,500/month vs ₹24,000/year. Monthly: ₹2,500. Annual: ₹2,000/month. Break-even: if you attend for more than 9.6 months, annual wins.
- Cloud storage: 100 GB at ₹130/month vs 200 GB at ₹210/month. Per-GB: ₹1.30 vs ₹1.05. The larger plan is cheaper per GB if you use more than 100 GB.
Frequently asked questions about unit pricing
Are supermarkets required to display unit prices? In the EU, Australia, and many US states, retailers above a certain size are legally required to display unit prices on shelf labels. In the UK, Trading Standards enforces unit price display. In practice, unit prices are often displayed in small print — this calculator helps when they are absent or confusing.
Should I always buy the lowest unit price? Not necessarily. Consider: expiry dates (perishables), storage space, quality differences between brands, promotional items with limited shelf life, and your actual consumption rate. Buying 3kg of a product at lower unit price creates no saving if 2kg goes to waste.
Why unit price matters — the shrinkflation problem
Shrinkflation is when manufacturers reduce the quantity in a package while keeping the same price. The product looks identical on the shelf, but you get less for your money. Without unit price comparison, this is nearly invisible to shoppers.
Real examples of shrinkflation (2022–2024): Chocolate bars reduced from 200g to 180g at the same price (11% effective price increase). Crisp/chip bags reduced from 200g to 175g. Coffee cans from 400g to 360g. Toilet paper rolls with fewer sheets per roll. Unit price comparison immediately exposes these hidden price increases.
Grocery unit price comparison guide
| Product Type | Best Unit | Common Trap |
|---|---|---|
| Breakfast cereal | Per 100g | Large boxes look better but check serving density |
| Pasta, rice, grains | Per 100g or kg | Bulk is usually cheaper — check expiry dates |
| Cooking oil | Per 100ml | Larger bottles almost always cheaper per litre |
| Cleaning products | Per 100ml post-dilution | Concentrated products dilute to 3–10× volume |
| Toilet paper | Per 100 sheets (not per roll) | Sheet count per roll varies enormously by brand |
| Nappies / diapers | Per nappy | Compare within the same size only |
Is the biggest pack always cheapest per unit?
No. Retailers sometimes price large sizes at a premium, particularly for store-brand products. Sale prices on medium sizes can undercut regular prices on large sizes. Promotional multi-packs sometimes cost more per unit than individual items. Always check the unit price on sale items and compare across all available sizes — the calculator above makes this instant.
Are supermarkets required to show unit prices? In the EU, UK, and Australia, retailers above a certain size must display unit prices on shelf labels. In many US states this is also required. In practice, unit prices are often in small print, use inconsistent base units across products, or are absent from promotional displays.
Should I always buy the lowest unit price? Unit price is the primary guide, but also consider: expiry date (a perishable at lower unit price may go to waste), storage space, quality differences between brands, and your actual usage rate. Buying the cheapest unit price only saves money if you use the full quantity before it expires.
How do I compare products sold in different units? Convert everything to a common unit. The calculator does this automatically: it converts grams, kilograms, ml, litres, ounces, and pounds to a standard 100g/100ml base for comparison. For items sold by piece (per egg, per bottle), compare by price per piece.
Sources & References
Sources: Federal Trade Commission Unit Pricing Rule, 16 CFR Part 424; Consumer Reports unit pricing research, 2023.
Unit price comparison: supermarket vs bulk buying
Unit price is the price per standard unit (per kg, per litre, per 100g). Supermarkets are required to display unit prices in the EU and UK — in India this is less consistent, making mental calculation essential. Example: 500g of rice for ₹45 vs 2kg for ₹160. Unit prices: ₹45÷500 = ₹0.090/g. ₹160÷2000 = ₹0.080/g. The 2kg pack is 11% cheaper per gram. But bulk only saves money if you will use the product before it expires — wasted food negates all unit price savings.
Price-per-use: the better metric for non-consumables
For products you use repeatedly, price-per-use is more informative than unit price. A ₹500 razor blade lasting 30 shaves costs ₹16.67/shave. A ₹150 disposable lasting 5 shaves costs ₹30/shave — nearly twice as much. Similarly, a ₹2,000 pair of running shoes lasting 800km costs ₹2.50/km. A ₹1,200 pair lasting 400km also costs ₹3.00/km — the expensive shoes are actually cheaper per km. This principle applies to: coffee pods vs ground coffee, paper towels vs cloth, fast fashion vs quality clothing. Related: Percentage Calculator.