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Nonparametric tests

Mann-Whitney U Test Calculator

Compare two independent groups when the outcome is ordinal or not normally distributed. Small samples without ties get an exact p-value.

Free · No sign-upReplaces SPSS · PrismWorks with your data
Updated · By Bibin Xavier

Data 90 × 12

Paste from Excel, or drop a CSV, TSV or Excel file here.
Example data 90 rows, 12 variables. Data stays in this browser tab.
IDtext · 90 levelsGrouptext · 3 levelsGendertext · 2 levelsAgenumericHours_StudynumericAnxietynumericMotivationnumericPre_ScorenumericPost_ScorenumericExam_ScorenumericPassednumeric · codedSatisfactionnumeric · coded
S001ControlMale2311.2294.660626712
S002WorkshopFemale233.9283.554705402
S003OnlineFemale1810.132455576603
S004ControlMale2613.6413.552555903
S005WorkshopFemale229.7273.656636504
S006OnlineFemale207.9323.865826502
S007ControlFemale206.328372836103
S008WorkshopMale228293.164726213

Variables and options

Results update automatically when you change an option.

Results

90 rows · example data
Table 1

Ranks

GroupnMedianMean rankSum of ranks
Control303.0020.85625.5
Workshop304.0040.151204.5
Table 2

Test statistics

Mann-Whitney UWilcoxon WzpEffect size r
160.5625.5-4.47< .001.577

Note. Asymptotic p with tie and continuity corrections.

Medians by group

Interpretation

Satisfaction was significantly lower in Control than in Workshop (effect size r = .577, strong).

A Mann-Whitney U test indicated a significant difference between Control (Mdn = 3.00) and Workshop (Mdn = 4.00), U = 160.5, z = -4.47, p < .001, r = .577.

How to cite this tool

Using these results in a thesis, journal article, report or class assignment? Please cite this free tool so others can find it. It keeps the site free.

APA 7

Xavier, B. (2026). Mann-Whitney U Test Calculator [Web application]. FreeStatisticalTools.com. https://freestatisticaltools.com/mann-whitney-u-test-calculator/

BibTeX 

@software{xavier_mannwhitneyutest_2026,
  author = {Xavier, Bibin},
  title = {Mann-Whitney U Test Calculator},
  publisher = {FreeStatisticalTools.com},
  year = {2026},
  url = {https://freestatisticaltools.com/mann-whitney-u-test-calculator/},
  note = {Web application}
}

Suggested sentence for your methods section: “The analysis was carried out with the free Mann-Whitney U Test Calculator tool on FreeStatisticalTools.com (Xavier, 2026).”

What is the Mann-Whitney U test?

The Mann-Whitney U test compares two independent groups using ranks instead of raw values. It is the nonparametric alternative to the independent t-test and suits Likert ratings and skewed data.

When to use the Mann-Whitney U test

Use it instead of the independent t-test for ordinal outcomes such as Likert ratings, or when the outcome is clearly non-normal with small groups.

Assumptions

  • Independent observations.
  • An ordinal or continuous outcome. To compare medians, the two distributions should have a similar shape.

How to use this tool

  1. Enter your data. Paste columns from Excel, Google Sheets or SPSS with variable names in the first row, or upload a CSV or Excel file. The example data shows the expected layout.
  2. Choose the variables. Select the dependent variable, grouping variable, group 1 and group 2.
  3. Read the results. Results update automatically. Read the plain-English interpretation, then use Copy table to paste APA-style tables into Word and Copy for the results sentence.

How to report the Mann-Whitney U test in APA style

“Satisfaction was higher in the Workshop group (Mdn = 4) than Control (Mdn = 3), U = 271, z = −2.68, p = .007, r = .35.”

Frequently asked questions

When should I use a Mann-Whitney U test?

Use it to compare two independent groups when the outcome is ordinal or clearly non-normal with small samples.

Is the Mann-Whitney test the same as the Wilcoxon rank-sum test?

Yes. They are equivalent tests with different statistics; this tool reports both U and W.

How is the effect size r calculated?

r = |z| / √N. Values of .1, .3 and .5 are usually read as small, medium and large.

Related tools

Wilcoxon Signed-Rank Test CalculatorNonparametric test for two related measurements, the alternative to the paired t-test.Kruskal-Wallis H Test CalculatorNonparametric comparison of three or more groups, with Dunn’s post-hoc tests.Friedman Test CalculatorNonparametric test for three or more related measurements, with Kendall’s W.

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