Family history silhouette - genealogy date formatting guide

Have you ever looked at "12/1/2020" and wondered if that's December 1st or January 12th? This confusion is exactly why genealogists worldwide use a standardized date format. Learn the universal format that works across Ancestry.com, FamilySearch, and all GEDCOM-compatible software.

In This Article

The Standard Genealogy Date Format

What is the correct date format for genealogy?

The standard genealogical date format is DD MMM YYYY (day-month-year), written as "15 Jan 1850". This format uses a two-digit day, a three-letter month abbreviation, and a four-digit year. This eliminates confusion between American (MM/DD/YYYY) and European (DD/MM/YYYY) conventions by spelling out the month.

For genealogy in general, and Ancestry.com in particular, I prefer day-month-year: 12 Jan 2020 vs. Jan 12, 2020. Either format is clear and works well on most platforms. Be sure to include the spaces between elements—they are necessary for Ancestry.com to properly interpret your dates.

Month Abbreviations

Always use standard three-letter abbreviations for months:

  • Jan, Feb, Mar, Apr, May, Jun
  • Jul, Aug, Sep, Oct, Nov, Dec

Why This Format Matters

I avoid writing dates as 12/1/2020 because that date is ambiguous—it can be interpreted as either 1 Dec 2020 (American convention) or 12 Jan 2020 (European convention). Using a spelled-out month eliminates all confusion.

This format is also the GEDCOM standard, meaning it transfers correctly between virtually all genealogy software including:

  • Ancestry.com
  • FamilySearch
  • MyHeritage
  • RootsMagic
  • Family Tree Maker
  • Legacy Family Tree

Handling Unknown or Uncertain Dates

What do you do when you don't know the exact date? Genealogy platforms support date qualifiers—special abbreviations that indicate uncertainty:

Common Date Qualifiers

Qualifier Meaning Example When to Use
Abt About / Circa Abt 1850 When you have an estimated date based on other evidence
Bef Before Bef 15 Jan 1850 When you know an event occurred before a certain date
Aft After Aft 1820 When you know an event occurred after a certain date

Practical Examples

  • Baptism record found: If you find a baptism on 25 Oct 1944 but don't know the exact birth date, enter Bef 25 Oct 1944 for birth.
  • Census age calculation: If an 1850 census shows someone as 35, enter Abt 1815 for birth year.
  • Last known alive: If you find a record showing someone living on 10 Mar 1890 but don't know their death date, you can enter Aft 10 Mar 1890 in the death field.

Date Ranges and Partial Dates

When You Only Know Part of the Date

  • Year only: Simply enter 1850
  • Month and year: Enter Jan 1850
  • Approximate year: Enter Abt 1850

Date Ranges

FamilySearch supports date ranges using the format:

  • Bet 1850 And 1860 (Between 1850 and 1860)

Note: Ancestry.com does not fully support "between" date ranges in the same way. For Ancestry trees, using Abt 1855 is often more practical for mid-range estimates.

Common Date Formatting Mistakes

Avoid these common errors that can cause problems with genealogy software and record matching:

Mistakes to Avoid

  • Using numeric months: 01/15/1850 is ambiguous—is it January 15 or 15 January (European)?
  • Forgetting spaces: 15Jan1850 may not be recognized. Always include spaces: 15 Jan 1850
  • Non-standard abbreviations: Use Abt not "app", "apx", or "circa"—these are Ancestry's recognized type-ahead formats
  • Two-digit years: Always use four digits. 20 could mean 1920 or 2020
  • Calendar confusion: Be aware of the Julian to Gregorian calendar change (September 1752 in British colonies) when working with older dates

Frequently Asked Questions

What date format does Ancestry.com prefer?

Ancestry prefers DD MMM YYYY format (e.g., 15 Jan 1850). This is also the standard GEDCOM format used by virtually all genealogy software. Include spaces between elements for proper recognition.

How do I enter a date when I only know the year?

Simply enter the year: "1850". You can add "Abt" if it's an estimate: "Abt 1850". There's no need to guess month or day—partial dates are perfectly acceptable in genealogy.

What if I don't know the exact date but know it was before another event?

Use the "Bef" qualifier. For example, if someone was baptized on 15 Jan 1850, enter their birth as "Bef 15 Jan 1850". This documents your reasoning without guessing.

Will my date format transfer correctly to other genealogy software?

Yes! DD MMM YYYY is the GEDCOM standard supported by virtually all genealogy software including Ancestry, FamilySearch, MyHeritage, RootsMagic, Family Tree Maker, and Legacy Family Tree.

Should I use "circa" or "c." for approximate dates?

Use "Abt" instead. While "circa" or "c." is common in written genealogy, "Abt" is the standard abbreviation recognized by genealogy software and databases for automated searching.

Summary

  • Standard format: DD MMM YYYY (e.g., 15 Jan 1850)
  • Month abbreviations: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
  • Uncertain dates: Use Abt (about), Bef (before), or Aft (after)
  • Partial dates: Year only (1850) or month-year (Jan 1850) are acceptable
  • Consistency matters: The same format works across all major genealogy platforms

Ready to Organize Your Family Tree?

Consistent date formatting is just one part of maintaining a well-organized family tree. GenConverse offers AI-assisted tools and professional consultation to help you manage and validate your genealogy data across platforms. Try Genie, our conversational genealogy assistant, or contact us to discuss your family history research needs.