# Quartile Calculator Calculate Q1, median, Q3, interquartile range, and optional outlier fences for a numeric dataset > Canonical page: https://elysiatools.com/en/tools/quartile-calculator - **Category:** Math & Numbers - **Keywords:** quartile, q1, q2, q3, interquartile range, iqr, box plot, outliers ## Overview Calculate quartiles for a numeric dataset. Quartiles split sorted data into four parts: Q1 = 25th percentile, Q2 = median, Q3 = 75th percentile Use this tool to summarize distribution shape, build box-plot statistics, compute IQR, and flag possible outliers with the 1.5 x IQR rule. ## Inputs - **Dataset** (textarea): e.g. 7, 15, 36, 39, 40, 41 - **Quartile Method** (select) - **Decimal Places** (number) - **Include Outlier Fences** (checkbox) - **Include Summary Statistics** (checkbox) ## When to use - Summarizing the spread and central tendency of a dataset without being skewed by extreme values. - Calculating the necessary statistical values to construct an accurate box-and-whisker plot. - Detecting statistical outliers in experimental, financial, or survey data using the 1.5 x IQR rule. ## How it works - Paste or type your numeric dataset into the input field, separating numbers with commas, spaces, or newlines. - Select your preferred quartile calculation method, such as linear interpolation, exclusive percentile, or median of halves. - Choose whether to include outlier fences and summary statistics, and set your desired decimal precision. - The tool automatically sorts the data and outputs the Q1, median, Q3, and IQR in a structured format. ## Use cases - Data analysts evaluating salary distributions to find the median and middle 50% earning range. - Students and researchers calculating five-number summaries for academic statistics assignments. - Quality control engineers identifying defective product measurements that fall outside standard outlier fences. ## Frequently asked questions ### What is the interquartile range (IQR)? The IQR is the difference between the third quartile (Q3) and the first quartile (Q1). It represents the middle 50% of your data and measures statistical dispersion. ### How does the tool identify outliers? If you enable outlier fences, the tool uses the 1.5 x IQR rule. Values below Q1 - (1.5 x IQR) or above Q3 + (1.5 x IQR) are flagged as potential outliers. ### What is the difference between the quartile calculation methods? Linear interpolation estimates values between data points, exclusive percentile excludes the median when splitting halves, and median of halves simply splits the dataset into two equal parts to find quartiles. ### Can I paste data directly from Excel or CSV? Yes, you can paste raw numeric data directly from spreadsheets. The tool will automatically parse numbers separated by commas, spaces, or newlines. ### What do Q1, Q2, and Q3 mean? Q1 is the 25th percentile, Q2 is the 50th percentile (the median), and Q3 is the 75th percentile. 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