Z-Score to Percentile Calculator

Posted Comments

There are 30 Comments

December 30, 2011 | Brian R. wrote:

Thank you, Jeff, so much for making available this calculator. It is great. I have used it many times over several years. It is very handy for someone like me running a small non-proft research institute without a lot of "resources." 

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May 22, 2011 | janet wrote:

makes it easier to understand 

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May 1, 2011 | Roger Bachmann wrote:

This sure beats looking up the z-table in a book. Nice explanation as well. 

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January 20, 2011 | sean courtney wrote:

excellent resource. just what my students need. 

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December 21, 2010 | Jo wrote:

Clear and easy! 

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November 14, 2010 | Michelle Freier Raleigh wrote:

good graphic and verbal presentation 

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October 29, 2010 | anonomous wrote:

Be careful using this program. The answers are in percentages. If you want to use the results in equations or compare to probability z-score charts, you have to divide the right side result by 100. 

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October 21, 2010 | Robert Glidden Jr. wrote:

Fantastic work! 

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April 12, 2010 | saleh wrote:

Hi,
This calculation assumes a normal distibution of scores, right?
Lets say that I got a score of 404 in an exam and the mean is 271 and the SD is 50. The z-score will be 2.66 (z=x-m/sd).
Can I caluculate the percentile corresponding to the score of 404 without assuming a normal distribution of the scores?
Thank you 

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April 5, 2010 | Danielle Rice wrote:

I'd like to know what numerical method is used to calculate probabilities. Thanks 

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March 25, 2010 | anonomous wrote:

thank you very much helped a lot in my hw 

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March 8, 2010 | Aditi M Sengupta wrote:

5. The Maine Education Assessment (MEA), a test completed annually by all students in the state in select grades, has M = 250 and SD = 50. What MEA score separates the upper 30% of the cases from the lower 70%?(EDPS 621, Eastern Michigan University, Winter, 2010) 

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March 3, 2010 | Janella annabella Shontella Ivonovich wrote:

math should go die. 

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March 3, 2010 | Percepicia wrote:

is there anyway you can show us how to actually do math problems??? and not just tell us the answer???? k. thanks.
percepicia 

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January 26, 2010 | Stephanie wrote:

Thank you so much for this incredibly handy tool!It's so appreciated! 

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January 9, 2010 | anonomous wrote:

perfect. 

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November 12, 2009 | Peter Belamarich wrote:

great 

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November 6, 2009 | Kathy wrote:

The pictures are helpful--made me more certain I was using it correctly. I compared the answers to a z-table and both gave the same answer (for 1-sided), so I felt confident I was getting using the info correctly. I don't understand the statistics, just needed to be able to convert a Std Deviation Score to a Percentile for a market potential calculation. 

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September 30, 2009 | Sam wrote:

What was the formula that you used to find the area associated with each z-score? 

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May 28, 2009 | Tom wrote:

seen a couple people ask the same question, but i'm looking for an actual formula to convert the Z-scores to percentiles. can't find anywhere on the internet that has it. 

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April 17, 2009 | troy percival wrote:

i am writing a database and need to make calculations to turn z scores into percentages. I am enquiring if you can help me with the formula that operates the calculator. Many thanks 

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March 9, 2009 | Denise wrote:

for a population with a mean of 80 and standard deviation of 12, what is the z-score corresponding to x=71? 

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March 3, 2009 | Susan wrote:

6. An aptitude test has a mean of 220 and standard deviation of 10. find the corresponding z score for: a) a test score of 232 b) a test score of 212 

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January 26, 2009 | anonomous wrote:

6. An aptitude test has a mean of 220 and standard deviation of 10. find the corresponding z score for: a) a test score of 232 

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October 16, 2008 | Verena wrote:

Hi,
I have been using your tool to calculate percentiles from z-score values. Until like a week ago, it worked perfectly fine, but now, when I enter a z-score of 3, one-sided, the value under 100% should be the higher one (in fact, it should be close to 99). Now, however, the higher number is being reported under the % of area section - how can that be? 

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September 11, 2008 | Ivy wrote:

Your MS class all took the practice clinical certification exam. The following is a listing of the raw scores that you and your friends received. Compute the z scores for these raw scores where the mean is 55 and the standard deviation is 2.5. What is a “z” score? What does it tell you?

Scores: 60, 72, 48, 53, 56, 51, 50.5, 59.5
x (observation) = 8 mean = 55 standard deviation = 2.5

z = Observation - Mean
Standard Deviation

= 8 – 55 / 2.5 = - 18.8

I don't have a book to find the z score for -18.8. I am not even sure if that is possible to get a z score for -18.8. Thank you for your help. 

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June 24, 2008 | Cindy Searcy wrote:

How would I figure a z-score if the mean was 11.9, the std. deviation is .4 and I want to be 95% sure that a bag of chips did not weigh 12 Oz. as specified on bag, and I weighed 30 Bags? 

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May 15, 2008 | Alex wrote:

hey, can send me the formula that happens in the BG? 

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April 30, 2008 | Steve Kelner wrote:

I can't seem to do a negative z-score. Otherwise outstanding! 

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March 19, 2008 | Justin wrote:

I have a normal distribution of Homeruns per week with mean 8.3 and standard deviation of 1.1. My team is projected to hit 10 homeruns in a week while my opponent's team is projected to only hit 8. What is the likelyhood of my team hitting more homeruns during the coming week? I am guessing P(8

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