In 1 years there are 0.099934 decades. Meanwhile in 1 decades there are 10.006644 years. Keep reading to learn more about each unit of measure and how they are calculated. Or just use the Decades to Years calculator above to convert any number.
* Values rounded to 6 decimal places for readability
To convert years to decades, use this simple rule: 1 decade = 10 years.
Examples
A decade has 10 years. It’s a simple unit used for time spans, age ranges, and history.
Divide the number of years by 10.
Example: 45 years ÷ 10 = 4.5 decades.
Multiply the number of decades by 10.
Example: 3.2 decades × 10 = 32 years.
1 year equals 0.1 decades. That’s one-tenth of a decade.
5 years equals 0.5 decades. That’s half a decade.
20 years equals 2 decades. This is a common time span for long-term plans.
25 years equals 2.5 decades. It’s two full decades plus five years.
50 years equals 5 decades. People also call this a half-century.
100 years equals 10 decades. It’s also known as a century.
Yes. Decades can be decimals when the years don’t divide by 10 evenly.
Example: 7 years equals 0.7 decades.
Convert everything to years first, then divide by 10.
A quick method: years + (months ÷ 12) = total years; total years ÷ 10 = decades.
Example: 12 years 6 months = 12 + (6 ÷ 12) = 12.5 years; 12.5 ÷ 10 = 1.25 decades.
Rounding depends on how you’ll use the number.
Yes, a decade always means 10 years. It doesn’t change with leap years. Leap years add days, not years.
A decade is any 10-year period. For calendar decades, people often use years ending in 0 to 9 (like 1990 to 1999). Some use 1 to 10 (like 1991 to 2000). Both are used, so it helps to state the range.
It depends on age. Divide age in years by 10.
Example: 80 years ÷ 10 = 8 decades.
Decades make big time spans easier to compare. They’re common in timelines, trend charts, and long-term records like climate data or population stats.
The Calculate Box tool to convert years to decades uses the open source script Convert.js to convert units of measurement. To use this tool, simply type a years value in the box and have it instantly converted to decades.