500 g for 3, or four packs for 10.80?
3 ÷ 0.5 = 6 per kg
10.80 ÷ 2 = 5.40 per kg
The multipack costs 10% less per kilogram. Its total price is still higher, so the better purchase depends on how much you need.
Shopping and quantities
Unit Price Calculator
Compare different pack sizes on the same basis, including multipacks.
Compare two unit prices
Unit price comparison
Enter both offers, then select Compare.
- Offer A unit price
- Offer B unit price
- Offer A total quantity
- Offer B total quantity
Compare prices for the same quantity
- A's quantity priced at B's unit rate
- B's quantity priced at A's unit rate
All price amounts use your input currency. Unit prices, quantities, and savings percentages display 4 decimal places; equivalent prices display 2. ≈ marks rounding. The winner is determined before rounding.
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Examples you can check
750 mL for 4.50, or 1 L for 5?
4.50 ÷ 0.75 = 6 per L
5 ÷ 1 = 5 per L
The 1 L offer has the lower unit price, about 16.6667% less. At its rate, 750 mL would cost 3.75.
12 items for 3, or 20 items for 4?
3 ÷ 12 = 0.25 per item
4 ÷ 20 = 0.20 per item
The 20-item offer costs 20% less per item. For a single pack, leave the number of packs at 1.
Formula, units, and comparison rules
Total quantity = quantity in one pack × number of packs × unit conversion factor. Unit price is the total offer price divided by that quantity in kilograms, liters, or items.
The saving percentage is (higher unit price − lower unit price) ÷ higher unit price × 100. A zero price is allowed. If both prices are zero, both offers have the same unit price and no saving percentage is calculated.
Ounces and pounds here are avoirdupois mass: 1 lb = 0.45359237 kg and 1 oz = 0.028349523125 kg. US fluid ounces and Imperial fluid ounces measure volume: 1 US fl oz = 0.0295735295625 L; 1 Imperial fl oz = 0.0284130625 L. The two fluid ounces are different sizes.
Prices are compared by cross multiplication at 100 significant digits, which preserves the full comparison products within the stated input limits. Unit price division uses the same precision. Display rounding happens last, with exact halfway values rounded away from zero. Matching displayed prices can still have a different winner.
A lower unit price does not automatically mean the lowest checkout price or the best product. Differences in concentration, quality, waste, delivery, and taxes can affect the decision; enter final prices on a consistent basis.
References: NIST Unit Pricing Guide (2025), NIST Handbook 44 conversion tables (2026), and Measurement Canada unit definitions.
Common questions
Do I enter the price of one pack or the whole multipack?
Enter the total price for all the packs in that offer. For six 330 mL cans sold for 4.80, enter price 4.80, number of packs 6, quantity 330, and unit mL. You can also enter one pack with total quantity 1,980 mL; the result is the same.
Can I compare ounces with fluid ounces?
No. Ounces in the weight category measure mass, while fluid ounces measure volume. Converting between them requires the product's density. Select the same category for both offers.
Does the calculator add discounts, tax, or shipping?
No. Enter the prices you want compared in one currency. If an offer includes extra charges, include them consistently. The Discount Calculator can help find a discounted price first.
Why are two matching prices not always a tie?
The displayed unit prices have four decimal places, but the comparison uses the original inputs. A difference smaller than the displayed precision is still a difference. The result identifies a tiny percentage saving when needed.