The tool says the small pack costs 15.79% more per kilo: how do I turn that into what I would actually save in a year?

Example: oil, rice or sugar you use every week

A 1 kg pack at 22 and a 5 kg pack at 95. The tool shows:

• The big pack: 19 per kg, the Best value.
• The small pack: 22 per kg, 15.79% more expensive.
• The gap per kilo: 22 − 19 = 3.

If you use 60 kg a year, at home or in a small food business kitchen, switching to the big pack saves 3 × 60 = 180 a year. That is a number you can decide on.

Why the percentage alone is not enough

Compare that with something you buy rarely. In another comparison, a 400 g pack at 14 costs 35 per kg while a 1 kg pack at 25 costs 25 per kg, so the small one is 40% more expensive. A much bigger percentage, but if you only use 3 kg a year, the saving is 10 × 3 = 30. The large percentage on a rare purchase saved less than a sixth of what the small percentage on a staple did.

Steps

1. In the Unit-price comparison tool, enter both options and choose per kg under Show cost, or per litre for liquids.
2. Subtract the best option's price per kilo from the other's.
3. Estimate your yearly use in kilos, from past receipts if you can, or monthly use × 12.
4. Multiply the gap by the yearly use. Log your purchases in the Expense summary generator if you want a more accurate figure next time.

What you give up for the saving

• Cash up front: 95 in one go instead of 22 at a time. If cash is tight, that money may do more elsewhere.
• Shelf life: 5 kg saves nothing if part of it spoils before you use it.
• Space: the big pack needs somewhere suitable to store it.

If the small pack has a temporary discount, work out its price after the discount with the Discount calculator and compare again; the gap may vanish for as long as the offer lasts.