Reading timelines: BC, AD, BCE, CE and centuries

Before you start

Who it's for and what to know first

Subtracting numbers up to 4 digits.

Learn it

How it works

• BC (Before Christ) and AD (Anno Domini) are traditional labels. BCE (Before Common Era) and CE (Common Era) use the same numbers and are often used in a non-religious context.
• BC years count down towards year 1: 500 BC happened before 300 BC.
• There is no year 0. The year after 1 BC is AD 1. So from 50 BC to AD 50 is 99 years, not 100.
• Centuries: the 1st century is years 1–100, so the 20th century is 1901–2000. A quick rule: take the year's first two digits and add 1 (1066 → 11th century).
• Draw timelines to scale: if 1 cm = 100 years, space events accordingly.

Tips

Common mistakes

• Thinking 1900s means the 19th century — it is the 20th.
• Forgetting there is no year 0 when crossing BC to AD.