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    Standard Deviation Calculator

    Calculate standard deviation, variance, mean, median, mode and quartiles online free. Free online standard deviation calculator for sample or population data.

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    How to use Standard Deviation Calculator

    1. 1Paste or type your numbers separated by commas, spaces or new lines (a column copied from Excel or Google Sheets works)
    2. 2Choose Sample if your data is a sample of a larger group, or Population if it includes every value
    3. 3Read the standard deviation with its formula, plus mean, median, mode, variance, range, quartiles and more; click Copy results to save them

    Frequently asked questions

    How do you calculate standard deviation?▾

    Find the mean, subtract it from each value and square the result, add the squares, divide by n − 1 (sample) or N (population), then take the square root.

    Should I use sample or population standard deviation?▾

    Use population (divide by N) when your data includes every member of the group. Use sample (divide by n − 1) when the data is a subset used to estimate a larger group — this is the usual case in surveys, experiments and homework.

    What is the difference between mean, median and mode?▾

    The mean is the average (sum ÷ count), the median is the middle value when sorted, and the mode is the value that appears most often. The median is less affected by outliers than the mean.

    What is variance?▾

    Variance is the average squared distance from the mean — the standard deviation squared. Standard deviation is easier to interpret because it is in the same units as the data.

    How are quartiles calculated?▾

    Q1 and Q3 are the medians of the lower and upper halves of the sorted data, excluding the middle value when the count is odd — the method used by TI-84 calculators and most textbooks.

    Embed Standard Deviation Calculator on your website▾

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