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Paired Samples T-Test Calculator

Test whether the mean difference between two related measurements is zero, for pre-post designs and matched pairs.

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

Paired samples statistics

MeasurementnMSDSE
Post_Score9065.0911.051.16
Pre_Score9060.188.750.92

Note. Correlation between measurements: r = .820.

Table 2

Paired samples t-test

PairMean differenceSDSE95% CItdfpCohen’s dz
Post_Score − Pre_Score4.916.340.67[3.58, 6.24]7.3589< .0010.78

Means with 95% CI

Interpretation

Post_Score (M = 65.09) was significantly higher than Pre_Score (M = 60.18). The average change of 4.91 is a medium effect.

t(89) = 7.35, p < .001, dz = 0.78, mean difference = 4.91, 95% CI [3.58, 6.24].

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). Paired Samples T-Test Calculator [Web application]. FreeStatisticalTools.com. https://freestatisticaltools.com/paired-t-test-calculator/

BibTeX 

@software{xavier_pairedttest_2026,
  author = {Xavier, Bibin},
  title = {Paired Samples T-Test Calculator},
  publisher = {FreeStatisticalTools.com},
  year = {2026},
  url = {https://freestatisticaltools.com/paired-t-test-calculator/},
  note = {Web application}
}

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

What is a paired samples t-test?

The paired samples t-test checks whether the average difference between two related measurements is zero, as in before-and-after designs or matched pairs. Put each measurement in its own column and the calculator does the rest.

When to use a paired samples t-test

Use it when the same participants are measured twice, or when cases are matched in pairs.

Assumptions

  • Paired observations.
  • The differences are approximately normal. If not, use the Wilcoxon signed-rank test.

How to set up your data

Wide format: one column per measurement, with each row holding one participant.

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 measurement 1 (e.g. after) and measurement 2 (e.g. before).
  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 a paired samples t-test in APA style

“Scores rose from pre-test (M = 59.7) to post-test (M = 64.4), t(89) = 6.21, p < .001, dz = 0.65.”

Frequently asked questions

What is the difference between a paired and an independent t-test?

A paired test is for two measurements from the same people (or matched pairs), so it analyses the differences within each pair. An independent test compares two separate groups of people.

What is Cohen’s dz?

dz is the mean difference divided by the standard deviation of the differences. It is the standardized effect size that matches the paired t-test.

What if the differences are not normal?

Use the Wilcoxon signed-rank test, the nonparametric alternative for paired data.

Related tools

One-Sample T-Test CalculatorTest whether a sample mean differs from a known or hypothesized value.Independent Samples T-Test CalculatorCompare the means of two independent groups, with Levene’s test, Welch correction and Cohen’s d.One-Way ANOVA CalculatorCompare three or more group means, with Levene’s test, Welch’s F and Tukey HSD post-hoc tests.Two-Way ANOVA CalculatorMain effects and the interaction of two factors, with Type III sums of squares and partial eta squared.Repeated Measures ANOVA CalculatorCompare three or more measurements from the same subjects, with Mauchly’s test and Greenhouse-Geisser correction.ANCOVA CalculatorCompare group means while controlling for covariates, with adjusted means and a homogeneity-of-slopes check.

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