Beta To Cohen's D Calculator - Calculator Academy

Calculate Cohen’s d from beta, means and SDs, t and df, or raw group data, with Hedges’ g, Glass’ Δ, r, plus confidence intervals.

Beta to Cohen’s d Calculator

Choose a method, enter the known values, then calculate.

β to d

Means/SD

t / df

Raw data

β coefficient / mean difference

Units

Pooled SD of outcome

Units

Cohen’s d

Group 1 n, optional

Group 2 n

Confidence coefficient

Group 1 mean

Group 2 mean

Group 1 SD

Group 2 SD

Confidence coefficient

Glass’ Δ uses Group 2 SD as the control-group SD.

Mode of testing

t value

n1 or paired n, optional

Pre-post correlation for paired mode, optional Confidence coefficient

Group 1 data Group 2 data Confidence coefficient

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Beta to Cohen's d Formula

The following relationship can be used to calculate Cohen’s d from a regression coefficient β that represents a two-group mean difference (e.g., from a linear regression with a binary predictor coded 0/1, where β equals the difference in group means) and the pooled standard deviation of the outcome.

d = (β) / (s₍pooled))

Variables:

d is Cohen’s d (unitless)
β is the two-group mean difference (often the unstandardized regression coefficient for a 0/1 group indicator), in outcome units
s_pooled is the pooled standard deviation of the outcome, in the same outcome units as β

To calculate Cohen’s d in this two-group setting, divide the mean difference (β) by the pooled standard deviation of the outcome.

Beta to Cohen’s d Conversion Table (Assumes pooled outcome SD = 1.0)
β (mean difference, outcome units)	Cohen’s d (unitless)
0.10	0.10
0.20	0.20
0.30	0.30
0.40	0.40
0.50	0.50
0.60	0.60
0.70	0.70
0.80	0.80
0.90	0.90
1.00	1.00
1.10	1.10
1.20	1.20
1.30	1.30
1.40	1.40
1.50	1.50
1.60	1.60
1.70	1.70
1.80	1.80
1.90	1.90
2.00	2.00
*Assumes pooled outcome SD (s_pooled) = 1.0. Formula: d = β ÷ s_pooled.

What is Cohen's d?

Cohen’s d is a measure of effect size used in statistics to indicate the standardized difference between two means. In the common two-independent-groups case, it is calculated as the difference between the group means divided by the pooled standard deviation of the outcome. Cohen’s d is useful for comparing effect sizes across different studies and contexts because it is standardized (unitless).

How to Calculate Cohen's d?

The following steps outline how to calculate Cohen’s d for two independent groups (and how it connects to β in a simple regression with a 0/1 group indicator).

Define the two groups you are comparing.
Find the mean difference between the groups (M₁ − M₀). In a linear regression with a binary predictor coded 0/1, this mean difference is the unstandardized coefficient β for the group indicator.
Compute the pooled standard deviation of the outcome (s_pooled).
Calculate Cohen’s d: d = β ÷ s_pooled.
Optionally, verify your result using the calculator above.

Example Problem :

Use the following variables as an example problem to test your knowledge.

Regression coefficient / mean difference (β) = 0.5

Pooled standard deviation of the outcome (s_pooled) = 2

Cohen’s d = β ÷ s_pooled = 0.5 ÷ 2 = 0.25