The Gregorian Calendar
At present, the Gregorian calendar is the most commonly used worldwide. It uses the conventional year of Jesus Christ’s birth as a starting point.
BCE and CE
- CE (Common Era): Refers to years after the starting point. Formerly known as AD (Anno Domini). Example: 1947 CE.
- BCE (Before Common Era): Refers to years before the starting point. These are counted backward. Formerly known as BC (Before Christ). Example: 560 BCE.
Warning
Crucial Note: There is no “Year 0”. The year 1 CE follows immediately after 1 BCE.
Calculating Time Durations
To find how many years have passed between a BCE date and a CE date:
- Add the two numbers.
- Subtract 1 (because there is no year 0).
Example: How many years ago was 560 BCE from 2024 CE?
Units of Time
| Term | Duration | Example |
|---|---|---|
| Decade | 10 Years | 2010 to 2019 |
| Century | 100 Years | 21st Century (2001–2100) |
| Millennium | 1,000 Years | 3rd Millennium (2001–3000) |
Tip
Calculating Centuries: To find the century of a year, look at the hundreds place and add 1.
- Year 320 CE: Century CE.
- Year 1828 CE: Century CE.