In 2017 to 2019 CDC survey data, the mean age at first vaginal intercourse was 17.1 years for women and 17.2 for men ages 15 to 49. The survey measured vaginal intercourse between opposite-sex partners. It did not measure every meaning of sex or virginity, and 17 is not a recommended age or a deadline.
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What does the average age of 17 measure?
The CDC number is a mean, a single average that summarizes the reported ages. In the 2017 to 2019 National Survey of Family Growth, the mean was 17.1 years for women and 17.2 for men ages 15 to 49. The standard errors were 0.09 and 0.10 years, respectively.
Who got counted? The table covers women and men ages 15 to 49 in the U.S. survey and asks about first vaginal intercourse with an opposite-sex partner. The National Center for Health Statistics published it as a special tabulation from interviewer-administered questions. It is a national survey estimate, rather than a complete count of every person.
The narrow definition matters. Someone may use the word sex for oral sex, anal sex, a same-sex experience, or another intimate experience. Those events sit outside this particular average, even if the person considers one of them their first time.
Why virginity and first vaginal intercourse are different questions
Virginity has no single survey or medical definition. Planned Parenthood describes it as an idea that means different things to different people, and notes that people disagree about which experiences count as losing it. The CDC avoids that argument by naming the event it measured: first vaginal intercourse.
That wording also keeps the number from making a judgment about anyone's identity or experience. A person can decide that the survey's event does or does not match what first sex means to them. The survey cannot make that choice for them.
So the search phrase and the data do not line up perfectly. The best direct U.S. figure answers a narrower question than the headline wording suggests. Keeping the definition beside the number is more accurate than turning 17.1 into a universal age for losing virginity.
Is 17 the age when most people first have sex?
A mean does not show the age when the largest number of people had sex, and it does not say that most people had sex at exactly 17. People reported different ages, and the published mean summarizes those reports in one figure.
A separate CDC report gives a better view of the spread. Using 2015 to 2017 survey data for people ages 15 to 24, NCHS estimated that 21% of young women and 20% of young men had experienced first vaginal intercourse by age 15. By age 17, the estimated probabilities were 53% for young women and 48% for young men. By age 20, they were 79% and 77%.
Those percentages are cumulative probabilities calculated from age-specific rates. NCHS says they are not simple shares of the survey sample at each age. They also come from an earlier survey period than the 17.1 and 17.2 means, so the two sets belong beside each other as context and should not be blended into one result.
What CDC data shows about age at first vaginal intercourse
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| Measure | Women or young women | Men or young men | Survey period |
|---|---|---|---|
| Mean age at first vaginal intercourse | 17.1 years (SE 0.09) | 17.2 years (SE 0.10) | 2017 to 2019 |
| Probability by age 15 | 21% | 20% | 2015 to 2017 |
| Probability by age 17 | 53% | 48% | 2015 to 2017 |
| Probability by age 20 | 79% | 77% | 2015 to 2017 |
Keep the measures separate A mean age and a cumulative probability answer different questions. The probability rows also use an earlier survey period and a younger analysis group.
How to read it: The CDC definition is first vaginal intercourse. These figures do not cover every meaning of sex or virginity.
Download the table (CSV) ↓Does the average set a normal or recommended age?
No population mean can tell one person when to have sex. The number describes when an event occurred in a surveyed crowd. It does not measure whether each experience was wanted, safe, legal, satisfying, or right for the people involved.
There is also no late-age penalty hidden in the table. A person who has not had sex by 17, 20, or later is simply outside the group that had the event by that age. The average cannot grade their maturity, relationships, health, or future.
If you are making a personal decision, the relevant questions are whether everyone freely agrees, can communicate, can stop at any time, and can manage sexual-health risks. A national average cannot answer any of those questions for you.
Why do other pages give a different age?
Search results give a direct age, country lists, and personal discussions. Different numbers can come from different years, countries, age ranges, definitions, and survey methods. A page may also mix a mean with a median or repeat a survey without showing who answered.
Before comparing two figures, ask four questions: what counted as sex, who was surveyed, which years were covered, and whether the result is a mean, median, or cumulative probability. If one page measured any sexual experience and another measured vaginal intercourse, the figures do not answer the same question.
Country tables need extra care because comparisons can use different wording and collection years. The sources used here do not provide a comparable country ranking, so this article does not publish one.
How should you use the number?
Use 17.1 and 17.2 as dated national estimates for one defined event. Keep the 2017 to 2019 survey period, ages 15 to 49, and opposite-sex vaginal-intercourse definition attached. Read the numbers as a picture of that crowd, not a forecast for your own life.
For a related CDC measure, average body count explains the median lifetime number of opposite-sex partners among sexually experienced adults ages 25 to 49. It answers a count question rather than a timing question, and its denominator is different.
For a wider view of relationship interest and dating activity among young adults, Gen Z dating statistics keeps each survey measure and age group separate.
When you see a claim about the average age to lose virginity, check whether it gives the event, survey, population, and year. If those details are missing, the number may be memorable, but you cannot tell who was in the room.
