To find the best value between two or more products, calculate the unit price for each — the cost per gram, per litre or per item. Whichever option has the lowest unit price is the best buy, even if its total price is higher.
Example 1: Brand A: 400 g for £1.20. Brand B: 650 g for £1.95. Which is better value?
Step 1
Brand A: \(£1.20 \div 400 = £0.003\) per gram (0.3p/g)
Step 2
Brand B: \(£1.95 \div 650 = £0.003\) per gram (0.3p/g)
Step 3
Both cost the same per gram — equal value.
Example 2: Orange juice: 1 litre for £1.08 or 1.5 litres for £1.50. Best value?
Step 1
Small: \(£1.08 \div 1 = £1.08\) per litre
Step 2
Large: \(£1.50 \div 1.5 = £1.00\) per litre
Step 3
Large bottle is better value (£1.00/litre vs £1.08/litre).
⚠️ Always compare the same unit. If one price is per 100 g and another is per kg, convert first.
✓ Quick Check 1 — The Unit Price Method
Question 1 of 10
Multipack vs Individual
Example 3: 3 for £2.40 vs 5 for £3.75. Which is cheaper per item?
Step 1
Option A: \(£2.40 \div 3 = 80\text{p}\) per item
Step 2
Option B: \(£3.75 \div 5 = 75\text{p}\) per item
Step 3
Option B is better value at 75p per item.
✓ Quick Check 2 — Multipacks & Comparing Value
Question 1 of 10
Unit Price Calculator
Enter details for two products to compare their unit prices side by side.
Compare Two Products
Fill in both products above to compare unit prices.
✓ Quick Check 3 — Mixed Best Buys
Question 1 of 10
Practice: Unit Pricing
Unit price = total price ÷ quantity, then ×100 to get a price per 100 g/ml. Give answers in pence. Type your answer, then click Check.
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Question
Answer
Result
1
Brand A: 500 g for £1.50. Price per 100 g (pence)?
2
Brand B: 750 g for £2.10. Price per 100 g (pence)?
3
250 ml for £0.90. Price per 100 ml (pence)?
4
3 items for £2.40. Price per item (pence)?
5
5 items for £3.75. Price per item (pence)?
6
A 2-litre bottle costs £1.60. Price per 100 ml (pence)?
7
A 330 ml can costs 55p. Price per 100 ml (pence, 2 d.p.)?
8
A 4-pack of 125 g pots costs £2.00 in total. Price per 100 g (pence)?
9
A single 500 g tub costs £1.80. Price per 100 g (pence)?
10
Rice: 2.5 kg costs £2.75. Price per 100 g (pence)?
⚠ Things to Watch Out For
Comparing the total price, not the unit price: A larger pack is not automatically better value. Calculate price per gram (or per ml, per unit) for each option before comparing.
Dividing in the wrong order: Unit price = total price ÷ quantity. NOT quantity ÷ price. Getting this backwards gives a nonsensical answer.
Not using the same units: Compare price per gram with price per gram — not one per kg and one per g. Convert to the same unit first.
Assuming bigger is better: Sometimes the smaller pack is better value (e.g. if the large pack has a "luxury tax" or is part of a bundle). Always calculate both.
Rounding too early: Keep full decimal precision during calculation. Round only the final unit price for comparison. Early rounding can reverse the result.