How To Calculate Z Score From Percentage?

By A2Z Calculators | Last update: 27 December 2023

Understanding statistical measures like the Z score can be crucial in various fields, including physics. In this article, we’ll delve into the process of calculating the Z score from a percentage, breaking down the steps and providing examples for clarity.

Calculating Z Score from Percentage

Step 1: Convert Percentage to Decimal To start, convert the given percentage to a decimal. For instance, if you have 25%, convert it to 0.25.

Step 2: Determine Positive or Negative Z Value

  • If the decimal is greater than 0.5, expect a positive Z value.
  • If it’s less than 0.5, expect a negative Z value.

Step 3: Find the Corresponding Z Value Use a standard Z score table to find the Z value corresponding to the calculated decimal. If you encounter multiple close values, choose the one closer to a specific point (e.g., 0.25) or interpolate for better precision.


  1. If given 25%, convert to 0.25. Since 0.25 < 0.5, expect a negative Z value. From the table, the Z score is approximately -0.67.
  2. For 5%, convert to 0.05. Since 0.05 < 0.5, expect a negative Z value. The corresponding Z score from the table might be around -1.64.

FAQs on Z Score from Percentage:

What is the Z-score of 25%?

The Z score of 25% is approximately -0.67.

How do you find the Z-score of 5%?

The Z score of 5% is around -1.64.

How do you find the Z-score from a percentile?

Follow the steps mentioned earlier, converting the percentile to a decimal and finding the Z score from a standard table.