Comprehensive Calculator Guide
To see which of two packs is the better deal, divide each price by its quantity to get the price per kilo, litre or item, then compare. A 5 kg bag of rice for SAR 42 costs SAR 8.40 a kilo; a 10 kg bag for SAR 79 costs SAR 7.90 a kilo, about 6% less. Enter both packs and the comparison appears instantly.
Compare the unit, not the pack
Shelf prices alone tell you little because packs come in different sizes. Unit price turns each pack into the cost of one unit of product. The only rule is to measure both packs in the same unit: kilos with kilos, grams with grams, items with items.
Bigger is usually cheaper per unit, but not always: a promotion on the small pack can beat the large one. And a large pack only saves money if you use it before it expires.
Pricing multi-buy offers
Divide what you pay by the number of items you take. In a buy-2-get-1 offer on an SAR 15 item you pay 30 for three, so each costs SAR 10, a third off. In a second-at-half-price offer each item costs 75% of its price.
How to Use
- 01Enter the price and quantity of the first pack.
- 02Enter the price and quantity of the second pack, in the same unit.
- 03Compare the two unit prices; the lower one is the better deal.
- 04For a multi-buy offer, enter the total you pay and the number of items you get.
Formula Used
Unit price = pack price ÷ quantity | Saving = (higher unit price − lower) ÷ higher × 100Practical Examples
Example 1: rice
5 kg for SAR 42 is SAR 8.40/kg; 10 kg for SAR 79 is SAR 7.90/kg. The large bag saves SAR 0.50 per kilo.
Example 2: nappies by count
40 for SAR 45 is SAR 1.125 each; 64 for SAR 68 is SAR 1.0625 each, about 5.6% cheaper.
Example 3: milk
1 litre for SAR 6.25 against 2 litres for SAR 11.75, which is SAR 5.875 a litre.
Important Tips
- Convert kilos to grams (× 1,000) before comparing a pack labelled in grams.
- Compare brands by unit price too; the gap between brands is often larger than between sizes.
Common Mistakes to Avoid
- Comparing a pack in grams with one in kilos without converting.
- Dividing quantity by price instead of price by quantity, which flips the comparison.
Frequently Asked Questions
- How do I work out the price per kilo?
- Divide the pack price by its weight in kilos: 2.5 kg for SAR 30 is SAR 12 a kilo.
- Is the bigger pack always cheaper?
- Usually, but not always. Promotions can make the smaller pack cheaper per unit, so it is worth checking.
- How do I price a buy-2-get-1 offer?
- Divide what you pay by the items you take. An SAR 15 item in that offer costs you SAR 10.
- How do I find the percentage saved?
- Subtract the cheaper unit price from the dearer one, divide by the dearer one and multiply by 100.