Enter a comma-separated list of numbers in the Data Set field and the Decile Calculator splits your data into ten equal parts. You get back all ten decile values (D1–D10), plus supporting stats like count, sorted values, minimum, maximum, mean, range, and sum — all with a step-by-step breakdown.
Deciles (D1–D10)
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Count
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Sorted Values
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Minimum Value
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Maximum Value
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Mean
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Range
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Sum of Values
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A decile is one of nine threshold values that divide a ranked dataset into ten equal groups, each containing 10% of the data. D1 marks the bottom 10%, D5 is the median (50th percentile), and D9 marks the top 10% boundary. Deciles are widely used in education, finance, and health research to understand data distribution.
The calculator sorts your input values in ascending order, then uses the percentile interpolation formula to find each decile position. For each decile Dk, the rank is computed as L = k × (n + 1) / 10, then interpolated between adjacent sorted values if L is not a whole number.
First, sort your data in ascending order. Then, for each decile k (1 through 9), compute the locator value L = k × (n + 1) / 10, where n is the count of values. If L is a whole number, the decile is that ranked value. If L is fractional, interpolate between the two surrounding values: Dk = x[floor(L)] + (L − floor(L)) × (x[ceil(L)] − x[floor(L)]).
Enter your numbers separated by commas, spaces, or a mix of both — for example: 12, 45, 7, 99, 3. Negative numbers are fully supported. The calculator automatically strips any blank entries and sorts the values before computing deciles.
All three are quantiles — they divide sorted data into equal-sized groups. Quartiles split data into 4 parts (Q1, Q2, Q3), deciles split into 10 parts (D1–D9), and percentiles split into 100 parts (P1–P99). Decile D5 equals Quartile Q2 and Percentile P50, all of which represent the median.
You need at least 10 data points to make deciles statistically meaningful, since each decile group should ideally contain at least one observation. The calculator will compute results with fewer values, but interpret them with caution as the interpolation may produce less reliable results.
Deciles help you understand how values are distributed across a dataset without being skewed by extreme outliers. In education, they rank student scores; in finance, they group income or portfolio returns; in healthcare, they assess patient metrics. They offer a more granular picture than quartiles alone.
D5 and the median are the same value — both represent the 50th percentile, the point below which exactly half the data falls. D5 is simply the decile notation for what statisticians also call the median or the second quartile (Q2).