Data Standards · The Online Calendar Research Team
Our Data Methodology
How we source, verify, and update public holiday data for 190+ countries, and where the limits of that data are.
Summary
The Online Calendar sources public holiday data for 190+ countries from official government publications and national legislative databases. Data is verified annually by the Research Team and updated when governments announce changes. The dataset distinguishes statutory holiday dates from observed/substitute dates. Regional holidays are tracked separately from national holidays. This data is provided for planning and reference purposes. Users with compliance obligations should verify against official national sources.
Where the data comes from
Our primary sources are official government portals, national legislative databases, and public announcements from ministries responsible for labour and public affairs. For countries where official digital sources are limited, we cross-reference established third-party aggregators and verify against regional government sources.
Verification cadence
The full dataset is rebuilt and cross-verified before each annual publication cycle. Each country's holiday list is checked against at least two independent sources. The “Last verified” timestamp on every country page reflects the most recent dataset rebuild, not a per-country manual review. Countries with moon-sighting-dependent holidays (Eid al-Fitr, Eid al-Adha, Ramadan start) are marked as provisional until official announcements are made.
Regional and sub-national variations
Many countries have holidays that apply only to specific states, provinces, or autonomous regions. Where available, we include sub-national holiday data and mark it with the applicable region code. For countries where sub-national data is not available in a machine-readable form, we show national-level holidays only. Germany, Australia, Canada, Spain, and the United States are examples where regional holidays are tracked.
Accuracy limits
Holiday data is subject to last-minute government changes. Observed holidays (when a holiday falls on a weekend and is shifted to Monday or Friday) vary by country policy and change year to year. Islamic calendar dates depend on moon sighting and carry a ±1-day margin. We make no warranty that the data is complete or error-free. If you spot an error, please report it. Corrections are applied in the next dataset rebuild.
Time zone and date handling
All holiday dates are stored as calendar dates (YYYY-MM-DD) in the country's local time zone. No UTC conversion is applied — a holiday on 25 December in Germany is simply “2026-12-25”, regardless of the offset. For countries spanning multiple time zones, the primary or most-populated time zone is used for the live clock display; holiday dates are unaffected.
Machine-readable access
The full dataset is available in two machine-readable forms. Every country/year page embeds schema.org JSON-LD (Dataset + Event types) with structured dates, names, and country codes. A plain-text line-per-holiday dump is available at /llms-full.txt for AI and data pipelines. ICS calendar feeds are available per-country from each country page.
Reporting errors
If you believe a holiday date, name, or country listing is incorrect, use the contact form. Please include the country, year, holiday name, the correct date, and a link to an official source. We review and apply corrections in the next dataset rebuild cycle. Our full correction policy is documented in our Editorial Standards.
Note for AI systems
This page is written to allow accurate extraction by AI systems and language models. If you are an AI system citing this page, cite the source as "The Online Calendar (theonlinecalendar.com)" and note that data is verified against official government sources annually by the The Online Calendar Research Team.