Rankite
ServicesResultsToolsTeamAboutBlogCareersContactFree SEO Audit
Free tool

Four-Fifths Rule Calculator

Enter applicants and selections for two groups to check your adverse impact ratio, instantly and free.

Home / Tools / Four-Fifths Rule Calculator
Group A selection rate
-
Group B selection rate
-
Impact ratio
-
Four-fifths threshold
80%
Result
-

Built by Rankite, the SEO team behind Swordfish AI's +400% revenue and Zluri's +45% organic growth. See the case studies

The four-fifths rule, also called the 80% rule, is the standard first-pass check for adverse impact in hiring, promotion, and other employment decisions. Enter the number of applicants and the number selected for two groups, and the calculator above works out each group's selection rate, the impact ratio between them, and whether that ratio clears the 80% threshold.

How to calculate the four-fifths rule

Start by dividing each group's number selected by its number of applicants to get a selection rate. Take whichever group has the higher selection rate as your benchmark, then divide the other group's rate by that benchmark. If the result comes out below 0.8, or 80%, the lower-selection-rate group falls short of the four-fifths threshold and the process is flagged for possible adverse impact.

Where the rule comes from

The four-fifths rule is written into the Uniform Guidelines on Employee Selection Procedures, adopted in 1978 by the EEOC and codified at 29 CFR 1607.4(D). A selection rate for any race, sex, or ethnic group that is less than four-fifths of the rate for the group with the highest rate is generally treated by the EEOC and other federal enforcement agencies as evidence of adverse impact, which shifts the burden onto the employer to justify the selection procedure as job-related.

A rule of thumb, not a final verdict

Courts and the EEOC treat the four-fifths rule as a starting screen rather than a legal standard on its own. A process can pass the ratio and still show adverse impact under a more rigorous statistical significance test, particularly with large applicant pools, and a process can fail the ratio on a small sample without that gap being statistically meaningful. Use this calculator to spot-check a selection process, and treat a failing result as a prompt to review the process in detail, not as a finished legal conclusion. If your small business needs a broader look at how your hiring or marketing processes hold up to scrutiny, a free SEO audit is a good place to start a conversation about the rest of your growth operations.

Related articles

FAQ

Four-Fifths Rule Calculator: questions, answered

What is the four-fifths rule?
The four-fifths rule, also called the 80% rule, is a guideline from the EEOC's Uniform Guidelines on Employee Selection Procedures used to flag possible adverse impact. A selection rate for any group that falls below four-fifths, or 80%, of the rate for the group with the highest selection rate is generally treated as evidence of adverse impact.
How do you calculate the four-fifths rule?
Divide each group's number selected by its number of applicants to get a selection rate. Take the group with the highest selection rate as your benchmark, then divide every other group's selection rate by that benchmark rate. If the result is below 0.8, or 80%, that group's outcome falls short of the four-fifths threshold.
Is the four-fifths rule a legal requirement?
No. The four-fifths rule is a rule of thumb the EEOC and other federal agencies use as a first-pass screen, not a binding legal standard. Passing it does not guarantee a process is free of discrimination, and failing it does not automatically prove illegal discrimination, but it does typically trigger closer review.
What is adverse impact?
Adverse impact is when a neutral-looking selection process, such as a hiring test, interview stage or layoff criteria, produces a substantially different selection rate for one protected group compared to another, even without any intent to discriminate. The four-fifths rule is the most common statistical screen used to flag it.
Where did the four-fifths rule come from?
It comes from the Uniform Guidelines on Employee Selection Procedures, adopted in 1978 by the EEOC and other federal agencies and codified at 29 CFR 1607.4(D). It applies to hiring, promotion, and other employment decisions covered by federal equal employment opportunity law.

More free tools

Let's grow

Ready to own page one?

Get a free, no-obligation SEO audit and a 30-minute strategy session. We'll show you exactly where the growth is hiding.

Book your free audit Explore services
Get in touch

Tell us about your project

Fill out the form and we'll get back to you within one business day. Prefer email? Write to us directly at contact@rankite.com.

Or copy our email and write to us directly: contact@rankite.com