BC vs. BCE and AD vs. CE
BC/AD and BCE/CE are alternative era-label systems, and Chicago leaves the choice to the writer unless a field or community convention governs it. Placement also differs: AD traditionally precedes a year, while BC, BCE, and CE follow the year.
Both BC/AD and BCE/CE are established systems. Choose the convention expected by your field or style guide and use it consistently; Chicago notes that AD traditionally precedes a year, while BC, BCE, and CE follow it.
Key details
Important caveats
Placement Boundary
Do not assume all four abbreviations occupy the same position relative to a year.
Style Boundary
Follow the terminology expected by the field, community, publisher, or house style and keep the system consistent.
Further guidance
Practical Application
Choose BC/AD or BCE/CE according to the field, audience or house style and use one system consistently; also place the abbreviation correctly around the year.
Reader Check
Which convention does the publication require, and are you applying the different placement of AD versus BC/BCE/CE?
Worked Example
Examples: “AD 410,” “410 BC,” “410 BCE,” and “410 CE,” following the reviewed Chicago placement convention.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- BC/AD versus BCE/CE — Chicago Q&A (opens in a new tab)The Chicago Manual of Style · House-style guidance on BC/AD versus BCE/CE choice