Terms & conditions

Agreement

These terms govern your use of onlinepvaluecalculator.com and everything served from it ("the site"). By using the site you accept them. If you do not, please do not use it. There is no account to close and nothing to uninstall — closing the tab is sufficient.

What you may do

The site is free to use, with no sign-up, for personal, academic, and commercial purposes alike. In particular, you may:

• use results in coursework, theses, papers, reports, and internal business documents, without attribution and without a licence fee;
• share links to a calculator, including links that carry your inputs in the URL;
• reference the methodology page when you need to state how a number was produced.

The output of a calculation — the p-value, the effect size, the interval, the APA string — is not claimed as our property. A number computed from your data is yours.

What you may not do

• Republish the site's editorial content — the explanatory articles, interpretation prose, and page copy — as your own. Quote it with attribution instead.
• Present the calculators as your own product, or frame them inside another site in a way that implies that.
• Attempt to disrupt the site or the infrastructure serving it, or use automated requests at a volume that degrades it for others. The calculators run in your browser, so scraping the site is a poor way to compute in bulk anyway — use SciPy, R, or another library directly.
• Use the site in a way that breaks the law where you are.

Not professional advice

This is a calculator, not a statistician, and nothing here is professional advice — statistical, medical, financial, legal, or otherwise. The site cannot know whether your study design is sound, whether your data satisfy a test's assumptions, whether you have controlled for the right variables, or how many other tests you ran before this one. Those judgements determine whether a p-value means anything, and they remain yours.

For consequential work — clinical research, regulatory submissions, safety analysis, anything where a wrong answer causes real harm — treat this site as a check on your arithmetic and not as a substitute for expertise. Verify results against your primary analysis software before you rely on them.

Accuracy, and its limits

Considerable effort goes into correctness. Every distribution is implemented from published numerical methods and validated against SciPy to a relative error below 1 × 10⁻¹³; the algorithms, reference values, and known limits are published on the methodology page, and the validation suite is public.

That is a strong statement about the implementation, and it is deliberately not a warranty. Floating-point arithmetic has finite precision; extreme inputs reach documented limits; software has bugs. The site does not warrant that results are error-free or fit for any particular purpose, and a validated implementation cannot rescue a misapplied test. If you find a discrepancy with R, SciPy, SAS, or Stata beyond floating-point noise, tell us — that is a bug, and it gets fixed.

No warranty

The site is provided "as is" and "as available", without warranties of any kind, express or implied, including but not limited to warranties of merchantability, fitness for a particular purpose, accuracy, and non-infringement. There is no guarantee that the site will be available, uninterrupted, or free of defects.

Limitation of liability

To the fullest extent permitted by law, the site's operators are not liable for any indirect, incidental, special, consequential, or punitive damages, or for any loss of profits, data, research outcomes, or opportunity, arising out of your use of or inability to use the site — including any decision made on the basis of a result it produced. Because the site is provided free of charge, total aggregate liability is limited to zero.

Some jurisdictions do not allow the exclusion of certain warranties or the limitation of certain liabilities, so parts of the two sections above may not apply to you. Nothing here excludes liability that cannot lawfully be excluded.

Third-party services and links

Web fonts are requested from Google Fonts, and pages viewed in a language other than English are machine-translated by Google Translate. Those services are governed by their own terms and privacy policies, not by these. Machine translation is unreviewed: numbers are held out of the translation pass deliberately, but translated prose may not carry the precision of the English original, which is authoritative.

The site links to external references and comparisons. Those pages are not under our control and linking to them is not an endorsement.

Privacy

Calculations run entirely in your browser and nothing you enter is transmitted to us — a structural property of a static site with no backend, not merely a policy. The privacy policy sets out the full detail, including the one item stored locally and the third-party requests above, and forms part of these terms.

Availability and changes

The site is offered without any commitment to keep it running, and pages, calculators, and URLs may change or be withdrawn. These terms may also be updated; the date below records the current version, and continued use after a change means you accept it. Material changes to the privacy commitments will be noted on that page rather than made silently.

Governing law

These terms are governed by the laws of the United States, without regard to conflict-of-law rules. This does not deprive you of the protection of mandatory consumer-law provisions in your country of residence.

Questions

Questions about these terms, and corrections to anything on the site, go to the contact page.

Last updated: 10 August 2026