Age Difference Calculator

The age difference calculator tool calculates how many years, months and days the age gap is between two people. Whether it's a romantic relationship, friendship or family relation, this tool will give you the age difference and who is older.

The age difference doesn't change over time. If the two people were four years apart when they were born, then that age difference will still be there every birthday and it will always stay the same. So the age difference is actually just the amount of time between their birthdays.

Three methods for calculating age difference:

Since sometimes you don't know the exact date of birth this calculator offers three input methods based on what information is actually available.

Calculation by age: If both people's ages are already known then the age difference is simply the difference between their two ages.

Calculation based on date of birth: By entering the dates of birth (day, month, year) of both persons, you will get an accurate calculation of the age difference down to the day, with leap years also being correctly taken into account.

When calculating by year of birth: If only the year of birth is known, then you can calculate the difference between the two years to get the number of full years.

The vertical line represents the absolute value. Since the result must always be a positive number, it doesn't matter in which order the people are entered. A calculation tool then shows who of the two is older.

Example calculation:

Assume one person was born on April 17th, 1990 and the other person was born on August 29th, 1994. If you compare these two dates, you will find that the second person is 4 years, 4 months, and 12 days younger than the first person. This equates to exactly 1595 days.

Let's look at another example of a celebrity couple: Prince Charles was born on November 14th, 1948 while Diana Spencer came into the world on July 1st, 1961. A calculator shows that Diana was about 12 years and 7 months younger than Charles which equates to a difference of 4,612 days or just over 12.6 years.

This is how to calculate age in years, months and days.

To manually calculate the age difference in years, months and days you will need to adjust both dates and start with the largest unit.

First subtract the birth year. Next compare the month and day. If the later person's month and day is before the earlier person's month and day then it means that the later person's birthday has not yet occurred so one year will be subtracted.

Then you calculate the number of remaining full months and finally the number of remaining days. Manual calculations usually consider all months to have 30 days, ignoring leap years, which can cause the result to be off by one or two days when using pen and paper. This calculator calculates based on the actual calendar so that the number of days is correct.

Input information:

The table below shows three methods of input and what information is required for each.

Regardless of how you enter the information, you can switch between the units shown (years, months, weeks, days). You can also display the result as a combined number in the format "year/month/day".

The 'half your age plus seven' rule

There is a widely accepted rule of thumb for age differences in romantic relationships which states that you should not date someone who is less than half your age plus seven years old. This rule is said to have originated in France and was originally used to determine whether or not a woman was suitable for marriage. It is a social convention rather than a law or fact, however.

Let's say a 46 year old wants to date someone who is 27 years old. Half of 46 is 23, and adding 7 gives us 30. So the "acceptable" minimum age for a partner according to this rule would be 30. Since 27 is below that threshold, this combination does not meet the criteria of this policy. With an age gap checker on dating apps, you can test any two ages using this method.

Age differences in romantic relationships

One of the most important aspects that people look at when they are looking for a relationship is age gap but actual data shows that it's not as alarming as rumors suggest.

According to current population statistics, the average age difference in heterosexual couples in the USA is about 2.3 years. In approximately one third of all marriages, the age difference is within a year. Furthermore, for another large proportion of married couples, men are two or three years older.

However, large age differences are also not uncommon. In the US and other Western countries, about 8% of heterosexual couples have a ten-year or more age difference. For same-sex male couples this figure is around 25%, while for lesbian couples it's about 15%. Same-sex couples tend to have larger age differences than heterosexual couples.

Studies have also shown that age gap can be associated with relationship satisfaction. A study in the Journal of Population Economics found that couples with an age difference of less than three years had higher satisfaction rates than those with four to six year age differences, and those with a seven-year or more age difference were the least satisfied. However, most romantic relationship experts agree that shared values, communication, and emotional connection are much more important than the age gap between two people.

Age gaps between couples in US:

For information, below are the age differences between married couples and unmarried couples in the US. The data is based on the report "Families and Living Arrangements" of the U.S. Census Bureau.

This calculator is only meant as a general reference. Age is just a number. Understanding, honesty and respect are much more important than the age difference between two people.

FAQs

How to calculate age difference between two people?

Subtract one person's age from the other and take the absolute value to get a positive result: Age difference = |Age1 - Age2|. If you know the birth dates, calculate the years, months, and days between the earlier date and the later date.

Does it matter which order you enter the two people?

No, it doesn't matter. As the calculator uses absolute values, it does not matter which person is entered first; the age difference will be the same. It will then show who of the two is older.

What is the formula to calculate age difference by year of birth?

You simply subtract the two birth years and take the absolute value: Age difference = |Year1 - Year2|. This will give you the age difference in full years. If the exact date is not known, this is sufficient.

What is the average age gap between couples?

In the United States, the average age difference between couples is about 2.3 years, and approximately one-third of married couples have an age gap of less than a year. Couples with more than a ten-year age gap make up about 8% of all heterosexual couples.

What is the 'age halved plus seven years' rule?

This is a social rule of thumb that says the minimum age for a partner should be at least your age divided by two, plus seven years. For someone who is 40, this would be 27 and for someone who is 30 it would be 22. This is a guideline based on social perception and not scientific or legal basis.

Are the age differences given in days accurate?

Yes. The calculators calculate the actual number of calendar days between two dates of birth, including leap years, so the number of days listed is accurate. Only manual calculations assuming each month has 30 days will give approximate values.