Interactive Playground

Try parsing EDTF strings in real-time. Select an example or type your own EDTF string to see how it's parsed.

Interactive EDTF Playground

Try parsing EDTF strings in real-time. Type or select an example below.

EDTF Input

Natural Language

Age and Birthdate

Parse age expressions and birthdates into EDTF intervals, then render them as human-readable strings.

All calculations use today's date: Friday, January 9, 2026

Age / Birthday Input

EDTF (for rendering)

What Can You Try?

Level 0 (ISO 8601 Profile)

1985-04-12                Complete date
1985-04                   Year and month
1985                      Year only
1964/2008                 Interval
1985-04-12T23:20:30Z      DateTime with timezone

Level 1 (Extensions)

1984?                     Uncertain year
2004-06~                  Approximate month
2004-06-11%               Uncertain and approximate
201X                      Unspecified digit (decade)
19XX                      Unspecified digits (century)
2004-XX                   Unspecified month
Y170000002                Extended year (5+ digits)
2001-21                   Season (Spring 2001)
../1985-04-12             Open-start interval
1985-04-12/..             Open-end interval

Level 2 (Advanced Features)

Y-17E7                    Exponential year
1950S2                    Significant digits
[1667,1668,1670]          Set (one of)
{1667,1668,1670}          List (all of)
?2004-06-~11              Partial qualification
2001-33                   Quarter (Q1)
[..1760-12]               Open set (earlier)
[1760-12..]               Open set (later)

Understanding the Output

Type

The type of EDTF value:

• Date: Simple date (year, month, day)
• DateTime: Date with time
• Interval: Range between two dates
• Season: Seasonal date
• Set: One of multiple dates
• List: All of multiple dates

Level

The EDTF conformance level:

• 0: ISO 8601 profile
• 1: Basic extensions (uncertainty, approximation)
• 2: Advanced features (sets, lists, partial qualification)

Precision

The precision of the date:

• year: Only year specified
• month: Year and month specified
• day: Complete date specified
• second: DateTime with seconds

Date Range (min/max)

Every EDTF value has a minimum and maximum possible date:

• min: Earliest possible date this value could represent
• max: Latest possible date this value could represent

For example, 199X (the 1990s):

• min: 1990-01-01T00:00:00.000Z
• max: 1999-12-31T23:59:59.999Z

Qualifications

Whole Date Qualifications

• Uncertain (?): The date might not be accurate
• Approximate (~): The date is estimated
• Uncertain & Approximate (%): Both uncertain and approximate

Partial Qualifications (Level 2)

Different parts of a date can have different qualifications:

• ?2004-06-~11: Year is uncertain, day is approximate
• 2004-~06-11: Only the month is approximate

Examples by Use Case

Cultural Heritage

156X-12-25                Artifact from 1560s
1887~                     Painting circa 1887
1777-09-XX?               Battle sometime in September 1777 (uncertain)

Historical Research

1400/1600                 Renaissance period
1939-09-01/1945-05-08     World War II
Y-17E7                    17 million years ago

Genealogy

1850~                     Birth circa 1850
1920/1925                 Death between 1920-1925
1875-21                   Marriage in Spring 1875

Archives

19XX-04                   Letter from April, 20th century
2004-XX                   Document from some month in 2004
[1667,1668,1670]          Manuscript from one of these years

Learn More

• EDTF Specification - Official standard
• Getting Started - Installation and usage
• API Reference - Full documentation
• Examples - Code examples