THE SHORT ANSWER
For the same product, 20% off beats 20% extra
When both offers start with the same regular price and package size, getting 20% extra product is equivalent to about 16.67% off. A 20% discount lowers the unit price by the full 20%. If the starting prices or sizes differ, compare the actual unit prices instead.
Why the labels are hard to compare
Imagine that one package says “20% more free” while the regular package next to it is marked “20% off.” The numbers look identical, but they change different parts of the purchase: one adds product, while the other reduces the price.
The easiest comparison is to put both offers on the same basis: the price for the same amount of product.
A $10, 10 oz example
These are hypothetical prices and sizes. Both offers apply to the same regular package.
Scroll sideways to see the full table.
| Offer | Price | Amount | Price per oz |
|---|---|---|---|
| Regular | $10.00 | 10 oz | $1.00 |
| 20% extra | $10.00 | 12 oz | About $0.83 |
| 20% off | $8.00 | 10 oz | $0.80 |
The discounted package costs about three cents less per ounce. The gap may look small on one purchase, but the percentage relationship stays the same at any regular price or package size.
How 20% extra becomes 16.67% off
With 20% extra, the new amount is 1.2 times the original. Dividing the price by 1.2 makes the unit price about 83.33% of the original. The remaining 16.67% is the effective discount.
For comparison, 25% extra is equivalent to 20% off, because dividing by 1.25 produces a unit price of 80%.
When the lower unit price is not the whole story
- You may not use the extra amount. Food that expires or a product you rarely use can turn “extra” into waste.
- The products may not be identical. Different ingredients, brands, or package formats can make unit price only one part of the choice.
- The regular prices or sizes may differ. Enter each offer's final price and amount in the Unit Price Calculator instead of comparing percentages alone.
If you might leave some unused, see the worked example of how much of a larger package you need to use before its lower unit price pays off.