**How many years is a decade? How many years is a century? And how many years is a millennium?** When we think of time, we often think of memories and the years gone by. But, we also think of the stories that have been passed down to us over centuries, by various generations. Whether we are reading a historical biography, or watching a period drama about an era gone by, we tend to relate to time with an image of what everyday life must have been like, in that time. For example, when we think of the past century, we tend to think of the World Wars that erupted, whereas, in the past two decades, all we can think about is computers, keyboards and now smartphones!

But if we really think about it – what is time and how do we measure it? Let us take a look at the true measurement of time with this article. When we think of **how long is a century**, or any other frame of time, we have to wonder what life must have been like that time as well. But first, let us understand the measurement of the eras that have come and gone.

**How many years is a decade?**

A decade is made by 10 years

- 10 decades = 10 × 10

- 10 decades =100 years

**how many years is a decade** this is a question that seems to have a simple answer. **A decade is usually 10 years long**. This means that a period of time that can be fit into ten years could be called a decade. For example, the period from 2000 to 2010 would be a decade. Yet, for many people, when they look at their personal history, this could vary and would not necessarily fit into exact multiples of ten. For example, if someone has been married for a period of ten years from 2003 to 2013, that would be a decade of their marriage. In fact, that would be the first decade of their married lives together.

So if you ask **how many years is a decade**, the correct assumption and definition are that it could be any 10 years at any period, but these ten years have to have come consecutively, one after the other. If there is a break of even a month or so, it goes right back to zero and the new decade starts from there. While many may say that time does not stop – but if an activity being measured is a personal one and in a decade, then it has to span those ten years that diligently follow each other. For example, I have worked in the same company for ten years – which would mean, I have worked there for a decade! If I left the job for a few months and came back, the calculation of the tenure or time period would begin from zero again.

**How many years is a century?**

A century is clearly 100 years. So, 2000 to 2100 would be a century. Yet, this is not the only way to measure a century. We see many signboards of old businesses and stores saying – been in business for a century. It could be from 1804 to 1904. That still makes it a century. So if someone asks how many years is a century or how long is a century, one must say that it is a hundred years at any given point in time. Yet, much like the above definition, the years must consecutively follow each other without fail and without a break in between. Only then one can authentically say that it has been 100 years.

This usually pertains to a period of time, an era in history or a long-standing business, practice, establishments like clubs and organizations that are involved in business or not for profit activities. This is due to the fact that a century cannot be a part of a personal history unless a person lives to 100 years or further – which is also quite rare!

**How many years in a millennium?**

Now, this is a sizable period of time – 1000 years makes a millennium! The interesting thing is that the turn of the century has been frequently recorded, especially since we developed and evolved technologies like printing of books and newspapers as well as the radio, TV and most recently, the digital media. Yet, the turn of the millennium – that is, when the world turned a thousand years older – has been recorded only once so far. This happened in the year 2000.

Now, this is due to the fact that we did not have the technology or the calendars to measure dates and the passage of time as we do now. In fact, we possibly did not know how to measure months and then years or even calculate how long a single day should be in order for it to turn into a week, then into a month, then into a year, a decade or a century. Earlier, people used to measure time with the positions of the sun and the moon; and months were measured with the passage of the seasons and the harvesting times.

This is also why we celebrate festivals in such a way – Thanksgiving in the US is during the fall harvest, while Baisakhi in India is the Spring harvest! Yet, we did not keep track of time in terms of years and we did not have a measure that said 30 days make a month and 12 months make a year. So, we did not know **how many years in a decade, how many years in a century**, so on and so forth.

So, if someone were to ask **how many years in a millennium** – we can now easily say a thousand years because we learnt and found the measure for a single hour, a single day. Then, we turned this into a measure called a week, a month, a year, a decade and finally a century. When we completed ten centuries or 100 decades – we realized that we have reached a new milestone that needs a new measure. We decided to call this the millennium!

**FAQs or Frequently Asked questions **

**Let us Look at the some of FAQs for ****how many years in a decade**:

**how many years in a decade**:

Let us look at a few commonly asked questions on this rather interesting concept and the story of time as measured in decades, centuries and a millennium.

### What are 20 years called?

The simple answer would be two decades. a group of 2 decades is what would make 20 years. While there is no specific for this period of time if someone asks how many years in a decade, we would say 10 years. So naturally, if someone asks how many years as in 20 years, we would say two decades. The baseline measure is called the decade and it can be applied to every set or group of ten years. For example, 40 years would be called 4 decades and 30 years would be called 30 decades. This would carry on until we reach 100 years, which would then make it a century.

### Is a decade every 10 years?

Yes, that is the correct assumption. A decade happens every 10 years. Yet, as we have explained above, this does not necessarily have to be a dividend often. It does not mean that a decade can only be from 1990 to 2000, or from 2000 to 2010. A decade can also be ten years of any milestone or activity in a person’s life – whether it is personal, professional or even social. The correct use of the term for every ten years is a decade.

### What is a 50 years called?

50 years would quite simply be termed as 5 decades. This is due to the fact that there are 5 groups of decades or ten years periods in 50 years. Therefore, this would simply make it five decades. In many instances, we can even term this as half a century since a century makes 100 years, which is half of the same. This means that you are halfway there and now only need to get over the same period of time (which is 5 decades) in order to hit the century mark. This is also a nice way to put it since it makes quite an impression over 5 decades. A Decade is a smaller measure, but a century seems like a far longer period of time. So instead of saying 5 small decades, we say half a large century – which makes it seem like a far larger chunk of time in one’s history and accomplishments. So, if someone asks how many years in a century, you can say 10 decades or 100 years. But 50 years definitely can be classified as half a century. Even in cricket, one hears half-century as the correct terminology when a player scores 50 runs. One does not hear 5 decades!

**How many years is a century?**

As we have mentioned above, a century is a sizable period of time and it is made up of a whopping 100 years! That is ten decades. So if anyone asks how many years is a decade, the simple answer is 10 years. But if someone asks how many years is a century, the answer can be given as – ten decades or 100 years. It is also one-tenth of a millennium. So, if someone asks how many years in a millennium – one can say ten centuries rather than just 1000 years! A century is 100 years, in simple and straightforward terms.

### What are 100 years called?

A 100 years can be called a century or ten decades. This is due to the fact that a decade consists of 10 years. So, if 20 years is 2 decades and 30 years is 3 decades, then 100 years can be a century or ten decades. The most common way of saying it is a century since that is the common measure of such a milestone in the simplest possible language and for maximum impact.

### What would you call 40 years?

Quadragennial – that is the correct term that is used for 40 years. This could be an anniversary of a marriage, the age of a person, or the span of a career or professional practice. Also, 40 years can be termed as 4 decades, but since this is quite close to the 50-year mark or the half-century mark, one can also use the term Quadragennial for this time frame. It would not be wrong to say 4 decades, either.

### What is an Oxygenarian?

While an octogenarian is a 100-year-old person, an oxygenarian is someone who is between the age of 80 and 90 years old. There are two interesting things that one can see here. One is that this term is used only to depict the age of a person rather than experience and milestones in one’s marriage, friendship or even profession. The second thing is that instead of saying 8 decades or 9 decades, the entire span of this decade comes under a single term that is Oxygenarian. This term cannot be interchanged with 9 or 9 decades, since a decade can signify experience and other milestones, while an oxygenarian is someone who has specifically attained those many decades in terms of his or her age.

### What is 500 years called?

There are many ways to look at this. For this, one can revisit questions like – **how many years in a decade**, **how many years in a century** and even **how many years in a millennium**. 500 years can be called half a millennium, just as we call 50 years half a century. This can also be termed as 5 centuries, which carries quite a bit of weight and sounds impactful as well – or at least far more impactful than 50 decades )which sound like short bursts of small periods of time when compared to a century or a millennium). Finally, it can also be termed as half a millennium, which is quite a robust way to put it!

So, did you like how we have broken down these time periods and time frames for you? If you have anything to add, you should comment or ask away!

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