A 500-gram coffee bag costs €4.50 and a one-kilogram bag costs €8.00. Both packages contain the same product and use weight, so kilograms provide a compatible baseline. The example ignores brand and quality differences to focus on arithmetic.
Enter the printed labels
Option A uses price €4.50, quantity 500, unit grams, and multipack one. Option B uses price €8.00, quantity one, unit kilograms, and multipack one. The currency label is €, which labels results but performs no exchange-rate conversion.
Normalize both quantities to kilograms
Five hundred grams becomes 0.5 kilogram because each gram is 0.001 kilogram. Option A therefore costs €4.50 ÷ 0.5 = €9.00 per kilogram. Option B already contains one kilogram, so its normalized unit price is €8.00 per kilogram.
Read the lowest entered price and savings
The one-kilogram bag has the lowest entered unit price by €1.00 per normalized kilogram. Relative to the €9.00 runner-up, 1 ÷ 9 × 100 is displayed as 11.11% after rounding. Buying it still requires €3.50 more at checkout.