Can An 18 Year Old Date A 21 Year Old? Everything To Know

Can an 18 year old date a 21 year old? What age gaps are appropriate for teenagers and young adults? We’re answering your most-asked questions about this topic below.

can an 18 year old date a 21 year old

The ideal age to start dating, the appropriate age difference between partners, and the age of consent are all issues that concern teens and their parents.

Conversations about dating and sexual behavior should begin by the age of 12 or 13, as American teens tend to start dating in middle school.

By high school, students are dating each other and older adults and likely having sex, so the opportunity for conversation passes quickly.

Can An 18-Year-Old Date A 21-Year-Old?

Legally and socially, there is no reason why an 18-year-old cannot date a 21-year-old.

If you are concerned about age differences in dating, there is a calculation that people commonly use, called the “dating age rule.” This equation calculates whether the age difference between partners is socially acceptable.

The dating age rule is as follows: divide the older person’s age by 2 and add 7. 

In this case, you will divide 21 by 2 and add 7: (21/2) + 7 = 17.5.

According to this rule, a 21-year-old can date anyone from 17 ½. However, it’s important to note that the age of consent is 18 in some states. This means that a 21-year-old and a 17 ½-year-old can not engage in sexual activities in those states.

The dating rule was developed to show a range of ages that will have a lot in common, such as popular culture, stage of life, physical ability, peer group, and so on, making a relationship more likely to work.

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Is It Legal For An 18-Year-Old To Date A 21-Year-Old?

Dating is never illegal, whatever the age difference, so long as there is no sexual activity. 

In this case, both the 18-year-old and 21-year-old are over the age of consent, so they would also be able to have a legal sexual relationship.

Is It Weird For a 21-Year-Old To Date An 18-Year-Old?

It is not weird or unusual for people of 18 to date people of 21, especially if they are both college students or working adults.

The three-year age difference will only influence a relationship if they are at completely different life stages, for instance, if one of them is a high-school student and the other is in college.

For example, an immature or innocent 18-year-old high-school student may find an older partner exciting or a way to prove that they are adult enough. An older partner may make the high schooler “cool” to friends or incite envy in others. A 21-year-old may have a job and spoil the younger partner or be able to buy alcohol for them to consume.

The problem with an age difference like this is an imbalance of power: the older partner has the car, the money, the life’s experience, and therefore the “authority” or upper hand in the relationship.

The younger partner may be susceptible to influence by the older and find themselves doing things they wouldn’t otherwise agree to, especially drinking alcohol or undertaking sexual activity.

So long as the younger partner is assertive, confident, and mature, and there is an equal power dynamic, there is nothing weird about an 18-year-old dating a 21-year-old.

Can A 21-Year-Old And An 18-Year-Old Have sex?

The age of consent in the US is either 16, 17, or 18, depending on the state. It is therefore legal for a 21-year-old and 18-year-old to have sex whichever state you live in.

The age of consent is the minimum age when someone is legally permitted and considered mature enough to consent to sex and differs from state to state and country to country.

How Old Can An 18-Year-Old Date?

Age difference in dating is a matter of personal preference and what is considered appropriate in your family and community. 

However, if you use the dating age rule, you can calculate the minimum age an 18-year-old should date. Divide the older person’s age by 2 and add 7: (18/2) + 7 = 16.

According to this rule, an 18-year-old can date anyone from 16. However, this only refers to dating, not engaging in sexual activity. In some states it is illegal for 18-year-olds to engage in sexual activity with 16-year-olds.

The dating age rule also calculates the maximum age of someone you should date. The equation works like this: your age minus 7 times 2.

For an 18-year-old, this would be: (18 – 7) x 2 = 22.

This rule suggests that an 18-year-old should date someone between the ages of 16 and 22.

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Related Questions

Can A 16-Year-Old Go Out With An 18-Year-Old?

A 16-year-old can date an 18-year-old and even have a legal sexual relationship in some states.

However, 16-year-olds are usually still in high school. They would likely need parental permission to date someone older than them, especially if the 18-year-old is working and in a different phase of life or community.

Can An 18-Year-Old Date A 20-Year-Old?

An 18-year-old can date a 20-year-old and have a legal sexual relationship. 

The relationship will be most successful if both partners are at college or working, rather than one still at high school and living with their parents.

Can 17-Year-Olds Date 21-Year-Olds?

A 17-year-old can date a 21-year-old and have a legal sexual relationship in certain states.

This four-year age gap may not be a problem unless there is a difference in maturity levels and an unequal power dynamic between the two, where the older partner is dominant, controlling, or demanding.

Unhealthy relationship patterns can develop if the younger partner is still at high school and living with their parents. For example, the older partner may encourage risky behavior, including sneaking out at night, underage drinking, and coerced sexual relationships.

Research shows that if the younger partner is female and the older partner is male, there is a statistically higher chance that she will be pressured into having sex before she is ready.

What Is The Appropriate Age To Start Dating?

The appropriate age for a teen to start dating will depend on the teenager’s readiness, the attitude of their parents, and the community’s customs. For most teens, this age is between 13 and 16.

In the US, most kids start dating in their early teens. The American Academy of Pediatrics’ research indicates that girls generally begin dating at 12 ½ and boys at 13 ½. 

Dating at this age is seldom one-on-one, but usually in a mixed-gender social group that goes to the movies or studies together, for example. Teens are not in couples but socialize with the whole group without particular commitment.

Groups allow teens to “hang out,” experiment with dating, and enjoy each others’ company in a safe setting, without any sexual tension or awkwardness.

This period is ideal for family discussion of dating, dating rules, and sexual activity.

Once teens are ready, they start going on one-on-one dates. Child psychologists and pediatricians suggest that teens are only prepared for this step at around 16. However, each teen is different – a teenager may be emotionally mature or immature or come from communities where one-on-one dating starts earlier or later.

After 16, couples will want to spend time alone together, often having sex. The CDC reports that by the age of 18, 55% of American teens will have had sex.


In the US, the sexual age of consent is between 16 and 18, depending on the state. However, the age of consent is often unrelated to the practice of dating.

Rules and customs around dating age and age difference between partners will differ depending on the teenager’s maturity, the family’s rules, and the community’s traditions.

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