How Much Did the Price Per Ounce Increase?
A product can get more expensive even when the shelf price change looks small. The real question is what happened to the old and new unit prices.
This guide focuses on the math: compare old price and size against new price and size, then calculate the unit-price increase. The shrinkflation calculator does this comparison for you.
📈 The Golden Rule
Do not compare only the dollar increase.
Compare the old unit price with the new unit price.
🧮 The 10-Second Formula
unit price = price / package size
unit price increase = (new unit price - old unit price) / old unit price
⚖️ The Comparison
| Version | Price | Package size | Unit price | Comparison result |
|---|---|---|---|---|
| Old package | $4.00 | 16 oz | $0.2500 per oz | Baseline |
| New package | $4.50 | 14 oz | $0.3214 per oz | About 28.6% higher per ounce |
The shelf price rose by $0.50, but the price per ounce rose much more because the package also got smaller.
How to Use the Calculator
The dedicated shrinkflation calculator compares old and new package values.
Enter:
- Old package: price $4.00, size 16 oz
- New package: price $4.50, size 14 oz
The calculator shows the unit-price increase and helps separate shelf-price changes from package-size changes.
⚠️ Common Unit Price Traps
The Shelf Price Trap
A small shelf-price change can hide a bigger unit-price change.
The Package Size Trap
A package can change size at the same time the price changes.
The Ounce vs Fluid Ounce Trap
Ounce vs fluid ounce matters: weight ounces and liquid fluid ounces are not the same unit family.
✅ Your 10-Second Price Increase Cheat Sheet
- Calculate the old unit price.
- Calculate the new unit price.
- Subtract old from new.
- Divide by the old unit price.
- Convert the result to a percentage.
Related calculators
Use these when package size, price, or unit type changed.
Next guide
If the price stayed the same but the package got smaller, this guide shows the simpler shrinkflation check.