Decade Defined: How Long Is A Decade?

    The word “decade” means several different things. To most people, it’s a period of ten years. But some people use the word to mean two or three calendar years and that’s okay. We use the term “decades” to talk about other things, like age groups and seasons. So what does a decade actually look like?

    Is A Decade Really Ten Years?

    No. The word “decade” can also mean 10 years of anything else, not just time. For example, the United States has been in a decade-long recession since 2008. 

    Similarly, a decade can be considered as the entirety of your life if you’re talking about your favorite television show or band’s discography (see: Led Zeppelin). But most importantly, when it comes to understanding how long ago something happened on an island known for being almost entirely populated by humans who coexisted with dinosaurs until recently (and probably still do), we usually just use one word “decades”.

    For many of us, the amount of time in a decade feels like a long time

    For many of us, the amount of time in a decade feels like a long time. But it’s actually not all that far apart from each other. The first decade of life (0-10) is only one year long and the second decade (11-20) is two years long. The third decade (21-30), however, spans four years.

    This means that if you’re born in 2016, your first decade started when you were 0 years old and ended when you turned 10 years old. In other words: “You’re almost 20”.

    Sometimes, though, it can seem to pass by in a flash

    It can seem to pass by in a flash when you’re having fun, or busy. Time can drag on if you’re bored or sad, but also when you’re waiting for something.

    Time moves quickly enough that it’s hard to tell how long one decade lasts before another begins or even if there will be another one at all.

    First and most obviously, 10 years is 10 years

    The first thing to know is that 10 years is a decade. A decade is made up of two years, and so 10 years is 10 times two or 20.

    This means that if you want to measure something in terms of decades, then you need to add one more number than what would be required for its measurement if it were measured in months or days instead of years. 

    For example: If someone tells me they’re going on vacation next month and I ask how long they’ll be gone for (in terms of weeks), my question will actually mean something totally different than it would if I asked them how many weeks they’ll be gone for (in terms of months).

    So when someone says “I have been working here for ten years,” what does this really mean? In context with their other statements about the length of their time at their job here at XYZ corporation, this sentence implies that this individual has been employed by XYZ Corporation since shortly after high school graduation which means his entire adult life has effectively been spent working there.

    Back in the day, a decade was a little bit different

    A decade is a 10-year period. It’s also a grouping of 10 years that began at the end of one decade and ended with the beginning of another (for example, we’re currently living in our second decade). And it’s also been used as shorthand for things that happened during this time period like “the 1990s”.

    The 20th century saw many major events: 

    • World War I.
    • World War II.
    • the Cold War and many more.

    The 21st century has already seen some big changes too. 9/11 happened right before our eyes (and so did Hurricane Katrina), but today we’re looking forward to more progress on climate change and other environmental issues.

    So is a decade really ten calendar years?

    The word “decade” can be used in two different ways: 

    • A 10-year period 
    • And a 10-year period. 

    If you say “10 years” or “a decade” you are talking about the same thing. A 10-year period of time. But if you say “ten years,” it means ten calendar years, not ten calendar days or weeks.

    If we’re talking about the word’s meaning as it relates to periods of time beyond just calendars, then we’ll have to look at other words that utilize some form of this idea. 

    For example:

    A century refers specifically to 100 years (and its plural forms). So if someone says they’re going on their first trip around the world in their lifetime which would make them 90 years old right now. They could also be saying that they’ll be traveling around for 100 years by their next birthday.

    There are also the second and third decades that start when we turn 12 and 20

    There are also the second and third decades that start when we turn 12 and 20. The first decade of life is from age 11 to 20. The second decade from 21 to 30. And finally, the third decade from 31 to 40.

    The first decade of your life is a time for exploration and discovery about yourself as well as others around you. In this period, you’re forming your identity by creating connections with other people in your community or school environment. You’re learning how to perform tasks like cooking healthy meals with friends on nights when they come over at 8pm when there’s nothing else planned except hanging out together doing homework together (which might not be fun).

    The first decade of life is from age 0-10

    1. The first decade of life is from birth to 10 years old. 
    2. The second decade of life is from 11-20 years old, and so on.
    3. The third decade of life (21-30) includes the teenage years and young adulthood when you’re going to college or getting a job for the first time.
    4. The fourth decade of life (31-40) is where many people start families, buy homes and have children.

    What About The Decade From 1-10, Or Even 2-11?

    In the United States, there are three different ways to measure age:

    • The first decade is from 0-10 years old.
    • The second decade is from 10-20 years old
    • The third decade is from 20-30 years old

    Some people count the first year as zero years old, and others count it as one calendar year old. Some people also count the second decade as zero-10, while others consider it one-11.

    We use the word “decade” to mean several different things. A decade is 10 calendar years (i.e, a year-long period of time). A decade is 10 years old in a calendar year (i.e, when you are 1 or 2).


    There are many different ways to define a decade, and it’s important to consider what each one means. If you’re looking for a definition of the word “decade,” try using this one “a period of ten years”.

    But if you want something more specific, look up the word’s origins in Latin or Greek and decide on your own how long it should be before deciding which type of decade is appropriate for your use case.


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