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.
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