Money & everyday · 3 min read
Unit Price Comparison: How to Tell Which Pack Is Cheaper
The method
Pick a common unit (per 100 g, per litre, per sheet). Divide each price by its quantity in that unit and compare.
| Pack | Price | Per 100 g |
|---|---|---|
| 500 g | 3.20 | 0.64 |
| 750 g | 4.35 | 0.58 |
| 1 kg | 6.20 | 0.62 |
Bigger is not always cheaper
The 1 kg pack costs 0.62 per 100 g, more than the 750 g pack at 0.58. Always compute rather than assume.
Use ratios
This is a ratio problem; see ratio and proportion and the ratio calculator. For unit conversions use the unit converter.
The 1 kg pack costs this much more per 100 g (percent change)
- That is a percent increase.
Step-by-step working 3 steps
- 1Find the change
0.62 − 0.58 = 0.04
- 2Divide the change by the old value
0.04 ÷ 0.58 = 0.06896552
- 3Multiply by 100
0.06896552 × 100 = 6.896552%
Frequently asked questions
How do I compare packs in different units?
Convert both to the same unit first, then compare unit prices.
Does cheaper per unit always mean better value?
Not if you will waste some — consider how much you will actually use.
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