Cronbach's Alpha Calculator

Figran

Paste survey responses to get Cronbach's alpha with item statistics.

  • Excel, SPSS or Qualtrics data
  • Alpha, omega and 95% CI
  • Item–total plot

Survey responses

Items

IncludeItemReverseScale
A1
A2
A3
A4
A5
Scale range
Missing values
Calculating…

Calculating…

Cronbach's alpha calculator examples

Explore simulated survey data, then replace it with your own.

Corrected item–total rα if item deleted−1−0.500.510.60.650.70.75Cronbach's αA1 (R)A1 (R)0.32A2A20.49A3A30.52A4A40.47A5A50.49

Agreeableness, one reversed item

Inspect item–total correlations for a five-item scale.

Simulated · 2,800 respondents · 5 items

A1AA1AA1A2A3A4A5C1CC1CC1C2C3C4C5E1EE1EE1E2E3E4E5N1NN1NN1N2N3N4N5O1OO1OO1O2O3O4O5−101

Five subscales

Compare several scales from the same questionnaire.

Simulated · 1,000 respondents · 25 items

Corrected item–total rα if item deleted−1−0.500.510.450.50.550.60.65Cronbach's αO1O10.40O2 (R)O2 (R)0.39O3O30.39O4O40.10O5 (R)O5 (R)0.36

Openness, a weaker scale

See why a small rise after deleting an item needs context.

Simulated · 500 respondents · 5 items

Corrected item–total rα if item deleted−1−0.500.51−1.5−1−0.500.5Cronbach's αC1C10.02C2C20.00C3C30.01C4C4−0.38C5C5−0.42

Before reverse-scoring

Find items that run against the scale.

Simulated · 500 respondents · 2 reverse-keyed items

Corrected item–total rα if item deleted−1−0.500.510.550.60.650.7Cronbach's αR1R10.43R2R20.43R3R30.43R4R40.50R5R50.37

Reasoning items scored 0 or 1

Calculate alpha for dichotomous responses.

Simulated · 700 respondents · 5 items

Corrected item–total rα if item deleted−1−0.500.510.780.80.820.84Cronbach's αQ1 (R)Q1 (R)0.59Q2Q20.63Q3Q30.59Q4Q40.63Q5Q50.62Q6Q60.58

Survey export with text labels

Map agreement labels from a Qualtrics-style export.

Simulated · 120 respondents · 6 items · Qualtrics layout

How to calculate Cronbach's alpha

From survey responses to a report-ready result.

  1. 1Paste responses

    Paste or import a table with one respondent per row.

  2. 2Choose items

    Select items, assign scales and reverse the required items.

  3. 3Inspect results

    Review alpha, the interval and item statistics.

  4. 4Copy or export

    Copy the report sentence or download the figure.

Interpreting Cronbach's alpha

Use the coefficient alongside the item statistics and the content of your scale.

Alpha summarizes internal consistency, but does not establish that a scale is unidimensional. A threshold of .70 is often used as a starting point; the required level depends on the decision and context. Very high values can indicate redundant items.

1Corrected item–total r2α if item deleted−1−0.500.510.450.50.550.60.65Cronbach's αO1O10.40O2 (R)O2 (R)0.39O3O30.39O4O40.10O5 (R)O5 (R)0.36
  1. Compare each corrected item–total correlation with zero.
  2. Compare each point with the dashed overall alpha line before considering item removal.
AlphaConsiderations
< .70A low value can reflect few items, mixed content or coding problems.
.70 to .95A commonly used starting point, depending on context.
> .95Very high values can indicate redundant items.

Alpha or omega

Alpha assumes equal factor loadings for its reliability interpretation. One-factor omega allows unequal loadings, but depends on the fitted model. Report the estimator and assess the model.

References: Tavakol & Dennick (2011) · Dunn, Baguley & Brunsden (2014)

Cronbach's alpha formula

For k items, alpha compares the sum of item variances with the variance of their total score.

Cronbach's alpha

α=kk−1⋅(1−∑σi2σtotal2)

McDonald's omega (one factor)

ω=(∑λ)2(∑λ)2+∑θ

Standardized alpha

αs=kr̄1+(k−1)r̄

After deleting an item

α−i=k−1k−2⋅(1−∑j≠iσj2σtotal−i2)

Feldt confidence limits

1−(1−α)Fpdf1=n−1,df2=df1(k−1)p=γ/2,1−γ/2γ=1−Confidence level

References: Cronbach (1951) · Feldt (1965)

Cronbach's alpha calculator FAQ

What is Cronbach's alpha?

It is an internal consistency coefficient for a set of items. It does not by itself prove unidimensionality.

What is a good Cronbach's alpha?

A value of .70 is a common starting point, but the context and consequences of a decision matter. Very high values may indicate redundant items.

Should I delete an item if alpha goes up?

Not automatically. Consider the size of the change and the content validity of the scale before removing an item.

Do I need to reverse-score items first?

Reverse-keyed items should be scored in the same direction. The calculator uses minimum plus maximum minus the original response.

Alpha or McDonald's omega?

Omega allows unequal loadings in the fitted one-factor model. Alpha and omega answer related questions under different assumptions.

How are missing values handled?

Listwise deletion excludes incomplete rows within a scale. Pairwise deletion uses available pairs and does not provide a Feldt interval.

Will my results match SPSS or R?

Use listwise deletion for the common SPSS Reliability Analysis setting or pairwise deletion for the default alpha function in the R psych package. Estimators and missing-value settings must match.

Is KR-20 the same as alpha? What about split-half reliability?

For items scored 0 or 1, alpha equals KR-20 (Kuder–Richardson Formula 20). Split-half reliability depends on the split and can use the Spearman–Brown correction 2r ÷ (1 + r).

How do I report Cronbach's alpha in APA style?

Report the number of items, alpha, confidence interval, sample size and reverse-scored items. You can also report omega and its model.

Check your scale's reliability

Turn survey responses into a clear reliability summary.

Calculate reliability