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Effect Size Calculator (Cohen's d)

Math Calculators

Cohen's d · pooled SD · small/medium/large

Quick Answer

Effect Size Calculator (Cohen's d): Cohen's d · pooled SD · small/medium/large. Effect Size Calculator (Cohen's d) uses standard math formulas to compute accurate results instantly.

How it works

  1. 1d=(x̄₁−x̄₂)/s_pooled — the gap in SD units
  2. 2s_pooled pools both groups
  3. 3Bands: 0.2 small / 0.5 medium / 0.8 large (Cohen 1988)
  4. 4Report effect size alongside the p-value

Group statistics

Cohen's d0.67Medium (0.5-0.8)
Pooled SD：15.00
Mean gap (SD units)：0.67 σ
d=0.5 means the average member of one group sits 0.5 SD above the other's — about 20% of the other group exceeds that line. Being unit-free, d is comparable across studies and meta-analyzable. Huge n yields tiny significant d (p<0.05 at d=0.05 means nothing practical): read d before p. Band cut-offs are conventions, not laws — prefer field-specific norms when they exist.

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How to Use

  1. Enter values or expressions: type directly into the Effect Size Calculator (Cohen's d) — keyboard friendly.
  2. Instant results: everything computes live as you type, no button needed.
  3. Follow the steps: the result panel shows full working and formula substitution.
  4. Copy or recompute: one-click copy; change any input to recalculate instantly.

Key Points

  • Effect Size Calculator (Cohen's d) is a free online math tool — open and use, no sign-up.
  • All calculations run locally in your browser; your data never leaves the device.
  • Key capability: Cohen's d · pooled SD · small/medium/large.
  • Results come with formulas and reference tables so you can verify every number.

Formula & How It Works

Effect Size Calculator (Cohen's d) formula

Effect Size Calculator (Cohen's d) uses standard math formulas to compute accurate results instantly.

FAQ

How do I use the Effect Size Calculator (Cohen's d)?
Open the page and fill in the input fields — results update automatically. Cohen's d · pooled SD · small/medium/large.
Are the results accurate?
Yes. All calculations use standard mathematical formulas and are verified for accuracy.
Is it free? Do I need to sign up?
Completely free. No registration, login or download required — just open and use.
Does it work on mobile?
Yes. The responsive design works on phones, tablets and desktops.
Is my data saved?
No. All calculations run locally in your browser. Nothing is uploaded or stored.

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Source & Updates

Standard mathematical formulas. All logic verified. Last updated: 2025-07

Last updated:

Formulas and content on this page are reviewed by the YiJianSuan team. For reference only — official sources prevail.

Maintained and periodically reviewed by the YiJianSuan editorial team — review process in ourEditorial Policy.

Cite this page: YiJianSuan. Effect Size Calculator (Cohen's d)[EB/OL]. https://www.yijiansuan.com/en/c/math/effect-size

Results provided by this tool are for reference only and do not constitute professional advice.