What Is Decade?
A decade is a unit of time. One decade is equal to ten years. People use decades to talk about long periods, like in history, fashion or personal life.
Definition
A decade is a period of ten full years. It can mean any block of ten years, starting from any year. For example, from 2003 to 2012 is one decade.
Sometimes people also use decade to talk about years that share the same tens digit, like the 1990s or the 2010s. In that case, a decade means from a year ending in 0 to a year ending in 9.
History / Origin
The idea of a decade comes from the number ten. The word goes back to old languages that used ten as an important counting step.
- It comes through Latin from a Greek word that meant a group of ten.
- People in the ancient world often grouped things by tens, like soldiers or years.
- As calendars and history writing grew, ten year periods became a simple way to divide time.
Today, the word decade is common in many languages and is a normal way to talk about time in history books, news and everyday speech.
Symbol & Abbreviation
The unit decade does not have a strict official symbol like some scientific units do.
- Most of the time people write the whole word decade.
- In short notes, some writers use dec, but this is not a fixed world standard.
- In science and engineering, people usually use years instead of a special symbol for decade.
Current Use Around the World
Decades are used in many ways in daily life, school and work.
- History and culture People talk about famous decades, like the 1920s or the 1960s, to describe styles, music and big events.
- Demographics Governments often count the population every decade with a census, for example every 10 years.
- Personal life People talk about life in decades, like your first decade as a child or your third decade as a young adult.
- Planning Long plans for business, cities or the environment may cover one or more decades.
- Science and data Some long term studies measure changes across several decades.
In everyday talk, many people name decades with a short form, such as the 80s, the 90s or the 2000s.
Example Conversions
Here are some simple ways to convert one decade into other time units. These are basic examples that use common approximations.
| Quantity | Equals |
|---|---|
| 1 decade | 10 years |
| 1 decade | about 120 months |
| 1 decade | about 3,652 to 3,653 days (if it includes leap years, using the usual average of 365.25 days per year) |
| 1 decade | about 87,660 hours (10 years × 365.25 days × 24 hours) |
| 1 decade | about 5,259,600 minutes |
| 1 decade | about 315,576,000 seconds |
Remember that the exact number of days in a decade can change a little, because some years in the decade will be leap years and others will not.
Related Units
Decades fit into a family of time units built from years.
- Year The basic unit here. 1 year is usually about 365 days.
- Lustrum A less common word that means 5 years. 2 lustrums make 1 decade.
- Decade 10 years.
- Score Sometimes used in older English to mean 20 years or 20 of anything. 2 decades equal 1 score when you are counting years.
- Century 100 years. 10 decades make 1 century.
- Millennium 1,000 years. 100 decades make 1 millennium.
Shorter units of time, like months, weeks, days, hours and minutes, can also be linked to decades through simple multiplication.
FAQs
How many years are in a decade
There are 10 years in one decade. This is always true, no matter which years you choose.
Does a decade always start in a year ending with 0
No. Any block of 10 years in a row is a decade. For example, 2005 to 2014 is a decade. When people say the 1990s, they usually mean 1990 to 1999, which is also ten years.
What is the plural of decade
The plural is decades. For example, you can say three decades or many decades.
How do I find my age in decades
To find your age in decades, divide your age in years by 10. For example, if you are 25 years old, 25 divided by 10 is 2.5, so you are two and a half decades old.
Is decade used in science
Yes, but not as often as years. In science, people usually measure time in years, months or days. They may use decades when they talk about long changes, like climate or population over many years.
Is a decade longer than a century
No. A decade is much shorter than a century. A decade is 10 years. A century is 100 years, which equals 10 decades.
Can decade mean ten of something other than years
In normal modern English, decade almost always means ten years. In older or special writing, it can sometimes mean a group of ten of something, but that use is rare today.