A century is 100 years — 10 decades or 1,200 months, and 36,524 or 36,525 days depending on its leap years.

100 years

1 century = 100 years

The same amount in every unit
Unit	Amount
Milliseconds	3,155,695,200,000
Seconds	3,155,695,200
Minutes	52,594,920
Hours	876,582
Days	36,524.25
Weeks	5,217.75
Months	1,200
Years	100
Decades	10

A century is 100 years; on the average year that is 36,524.25 days. A year is 365.2425 days on average (Gregorian calendar: 97 leap years every 400 years). A common year has 365 days (52 weeks and 1 day); a leap year has 366 (52 weeks and 2 days).

How it’s calculated

Every unit is converted through seconds: 1 minute = 60 s, 1 hour = 3,600 s, 1 day = 86,400 s, 1 week = 604,800 s. Months and years use the Gregorian average: 1 year = 365.2425 days = 31,556,952 s, 1 month = 1/12 year = 2,629,746 s.

Worked example with your numbers

1 century × 3,155,695,200 seconds per century = 3,155,695,200 seconds.
3,155,695,200 seconds ÷ 31,556,952 seconds per year = 100 years.

Quick answer

A century is 100 years — 10 decades or 1,200 months, and 36,524 or 36,525 days depending on its leap years.

Century: 100 years
Decades: 10
Months: 1,200
Millennium: 10 centuries

Every time unit in seconds, days and years
Unit	Seconds	Days	Years
1 millisecond	0.001	0.00000001157	0.000000000032
1 second	1	0.00001157	0.00000003169
1 minute	60	0.0006944	0.000001901
1 hour	3,600	0.041667	0.0001141
1 day	86,400	1	0.00273791
1 week	604,800	7	0.01916535
1 month	2,629,746	30.436875	0.08333333
1 year	31,556,952	365.2425	1
1 decade	315,569,520	3,652.425	10
1 century	3,155,695,200	36,524.25	100

1 decade = 10 years; 1 century = 100 years; 1 millennium = 1,000 years. Months and years use the Gregorian average (365.2425 days a year).

How it works

Centuries are counted from year 1, so the 21st century is 2001–2100 — though most people celebrate the turn of the century at 2000.

Frequently asked questions

How many years are in a decade?

10 years.