Relationship Age Gap Calculator

Calculate the age gap and what it means

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Frequently Asked Questions

What is the half-your-age-plus-seven rule?

An informal guideline: minimum acceptable partner age is half your age plus seven. Not a law or scientific rule.

Is this judgmental?

No. The calculator presents the mathematical result neutrally.

Is this relationship advice?

No. A fun calculator only.

Does it work in both directions?

Yes. Enter both ages and the tool calculates the result for both.

Is my data stored?

No. All calculations are browser-only.

Age Gaps in Relationships: Research and the Half-Plus-Seven Rule

The "half your age plus seven" rule is an informal guideline for the minimum age of a romantic partner that has been referenced in popular culture since at least the early 20th century. The formula: take your age, divide by two, add seven. A 40-year-old's minimum by this rule is 27. A 30-year-old's minimum is 22.

Where the rule comes from

The earliest documented reference to the rule appears in a 1901 French novel, though similar formulations appear in various European etiquette guides of the late 19th and early 20th century. It was originally framed as guidance for an older man seeking a younger wife, reflecting the gender dynamics of that era. The formula has no mathematical derivation from research — it is cultural convention that happens to produce age ranges that feel intuitively reasonable to many people in the contemporary Western context.

What age gap research actually finds

Demographic research on age gaps and relationship outcomes shows a consistent pattern: larger age gaps are associated with lower relationship satisfaction and higher dissolution rates, on average. A 2019 study found that couples with a 10-year age gap reported lower satisfaction than those closer in age, with satisfaction declining further for larger gaps. However, the effect is modest and highly variable — many age-gap relationships are highly satisfying and long-lasting.

The research also finds that age gap effects interact significantly with the direction of the gap (older woman/younger man vs older man/younger woman), the absolute ages of both partners, and the power differential in the relationship context in which it forms. A workplace relationship with a significant age gap carries different dynamics than one forming between two independent adults at equivalent life stages.

This tool's approach

This calculator presents the mathematical results without commentary on whether any particular age gap is appropriate. Age gap appropriateness is context-dependent, involves many factors this calculator cannot assess, and is ultimately a matter for the people involved.