Measuring Usability
Quantitative Usability, Statistics & Six Sigma by Jeff Sauro

zScore Calculator

Download an Excel workbook which calculates the percent of area under the normal curve from a z-score and finds the z-score from area under the curve.
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    $21.99     Now :  

If you will be making copies or distributing the product, please purchase the site license

This calculator can also be purchased for a discount as part of the zScore Package.


Features & Benefits

  • Get the exact area: No need to try and interpret hard-to-read z-score tables.
  • Calculates the area under the normal curve from a z-score.
  • Inverse Lookup: Finds the z-score from a percent of area under the normal curve.
  • Computes both 1-tailed and 2-tailed areas and z-scores with a visual reference.
  • Easily integrate the formulas into your spreadsheets

Who Should Buy

Anyone that needs a quick and easy way to convert z-scores into percentages or percentages into z-score.

Select Sample Screen Shots

zScore Calculator

zScore Calculator

Inverse Z-lookup with real-time graphs

Inverse Z-lookup with real-time graphs

Find a z-score from area under the curve. This calculator does an inverse z-lookup for 1 and 2-sided areas.

Calculator HomePage

Calculator HomePage

The two z-calculators are easily accessible from a home main page. Add links to data sets or include your data in the worksheet.

Area between two Z-scores and a real-time graph

Area between two Z-scores and a real-time graph

Finding the area between two z-scores requires several steps and is easy to make mistakes. The area-between calculator shows you with a real time graph and area from two z-scores.

Z-Scores and Area for a Sample Mean

Z-Scores and Area for a Sample Mean

Answers questions and shows the calculations for questions such as "What is the probability of 25 students scoring a 78 if the population mean is 60 and sd is 7?"

Z-Scores and Area for a Single Data-Point

Z-Scores and Area for a Single Data-Point

Answers questions and shows the calculations for questions such as "What is the probability of a 78 if the population mean is 60 and sd is 7?"

Batch z-score entry

Batch z-score entry

Includes two batch calculators which allow you to enter many rows of z-scores or percentages and get fast results, such as from copying and pasting from other data-sources.

Find the area under the normal curve with real-time graphs

Find the area under the normal curve with real-time graphs

Just enter the z-score and you can find the 1 and 2-sided area under the curve. The results are precise to over 8 decimal points.

Z-Score Calculations

  • Percent of Area from Z-score
  • Z-Score from Percent of Area (Inverse Lookup)

What Customers are Saying:

We are very impressed with the zScore Calculator tool.

Dr. Ann-Margaret Esnard
Director, Visual Planning Technology Lab
Florida Atlantic University
This is a great product, it is a lot faster than looking through the table and you know you won't make mistakes looking the scores up. Highly recommended.

Dr. Hassan Ramadan
Residency Program Director
Head & Neck Surgery
West Virginia University
The ZScore calculator not only simplifies the statistical process of using z-scores but it makes evaluation results easier to explain.

Dr. Jim Kimes
Prof. Emeritus, University of Missouri-St. Louis and Cross-word Puzzle maven


    $21.99     Now :  

If you will be making copies or distributing the product, please purchase the site license All major credit cards, debit cards and PayPal Accepted.
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