"125% More" Feels Like "25% More"

Customers believe that:

150% more than [number] = 150% of [number]

But these variations are different:

• 150% of 100 = 150
• 150% more than 100 = 250

Customers equate these statements, but they differ by a full 100 percent. That’s why it’s called the Off by 100% Bias (Fisher & Mormann, 2022).

Therefore, be careful with percentages that depict a relative change. Suppose that you increased a product’s battery life from 4 hours to 9 hours.

• Don’t say: Battery lasts 125% longer.
• Say: You doubled the battery life.

The latter is technically smaller, but it sounds bigger.

• Fisher, M., & Mormann, M. (2022). The off by 100% bias: the effects of percentage changes greater than 100% on magnitude judgments and consumer choice. Journal of Consumer Research, 49(4), 561-573.