Shrinkflation checker
Same price, smaller bar? Enter the old pack and the new one to see how much more you really pay for every gram or millilitre.
The real change
Shrinkflation
The pack got smaller and you pay more for each gram, millilitre or item.
- Size −10%
- Shelf price +5.4%
| Unit price | Before (200 g) | Now (180 g) |
|---|---|---|
| per 100 g | £0.925 | £1.08 |
| per kg | £9.25 | £10.83 |
| per oz | £0.262 | £0.307 |
| per lb | £4.20 | £4.91 |
At the old unit price the new pack would cost £1.67, so you pay £0.28 more for it. The old 200 g pack would cost £2.17 at today's unit price.
Size and price, together
Shrinkflation is when a product gets smaller while its price stays the same, or falls by less than the size did. The shelf price hides it; the unit price shows it. Official statisticians look at it the same way: the UK's Office for National Statistics adjusts for changes in a product's weight or volume when it measures inflation, so a smaller pack at the same price counts as a price rise.
Real change = (new price ÷ new size) ÷ (old price ÷ old size) − 1
In the example, a 200 g bar at £1.85 became a 180 g bar at £1.95. The shelf price went up 5.4%, but you get 10% less, so every gram costs 17.1% more.
Finding the old size
Look for an old wrapper or receipt, a photo on your phone, or your online order history, which usually lists the pack size. Make sure it's the same product: a "new recipe" can change more than the size.
Sources
- Office for National Statistics, Shrinkflation: how many of our products are getting smaller? (21 January 2019): how size changes are adjusted for in consumer price statistics.
- NIST, Guide to the SI, Appendix B.9: unit conversion factors.
Questions
Why does a small size cut make such a big difference?
The price is spread over less. A pack that is 10% smaller at the same price costs 11.1% more per gram, because 1 ÷ 0.9 = 1.111.
Can I compare a pack in grams with one in ounces?
Yes. Pick each pack's own unit and the checker converts them. It can't compare a weight with a volume.
What if the new pack is better value?
The checker says so. A pack can shrink and still be better value if its price fell by more than its size.