Data sources and methodology
How the site turns structured geographic data into country-specific clocks, calendars and planning tools.
Time and UTC offsets
Live clocks use named IANA time zones through the browser’s Intl implementation. Date-specific conversion converts a local wall-clock time into an instant and formats that instant in the destination time zone, so historical and future daylight-saving rules are applied for the selected date.
Daylight saving time
Country/year clock-change pages are generated from IANA time-zone rules. Live clocks calculate the active offset in the visitor’s browser rather than relying on a hard-coded summer or winter offset.
Public holidays
GlobalTimeGuide does not guess missing holiday dates. Where coverage is supported, public-holiday features use OpenHolidays open data. United Kingdom bank-holiday schedules for 2026 and 2027 are embedded from GOV.UK; United States federal-holiday schedules for 2026 and 2027 are embedded from the U.S. Office of Personnel Management. Unsupported holiday pages are kept out of search indexing rather than populated with unverified dates.
OpenHolidays data is available under the Open Database License (ODbL). Government schedules can change when one-off holidays are announced, so critical travel, payroll or legal decisions should be confirmed with the relevant authority.
School holidays
School calendars are frequently set by states, regions, municipalities or individual education authorities. Dedicated school-holiday pages are therefore limited to markets where subdivision or zone information can be preserved. For critical dates, the page directs visitors to the relevant official local authority.
Working days
Working-day calculations remove the selected country’s normal weekend pattern and, where supported, verified public holidays. United Kingdom year totals use England & Wales as the stated baseline; U.S. year totals use the federal OPM schedule. Employer, regional and local rules can change the practical total, so results are planning estimates rather than legal or payroll advice.
Sunrise, sunset and weather
Year pages use a NOAA/USNO-style astronomical calculation from stored city coordinates and the city’s IANA time zone to provide practical sunrise, solar-noon, sunset and daylight estimates. Live weather/solar widgets can request current data from Open-Meteo. Weather data never affects the time-zone calculation.
Quality principle
The site prioritizes a smaller set of useful, pages backed by named sources over mass generation. Existing URLs are preserved where possible, and pages without sufficiently reliable source coverage are excluded from search indexing instead of being filled with assumptions.
Holiday and school-calendar sources
GlobalTimeGuide uses OpenHolidays open data for supported markets, GOV.UK for UK bank holidays, and the U.S. Office of Personnel Management for U.S. federal holidays. The previous holiday feed is no longer used in production. Unsupported country/year holiday pages are kept out of search indexing rather than populated with guesses.
OpenHolidays data is provided under the Open Database License (ODbL). Government schedules remain subject to their source terms and can change when one-off holidays are announced.
School-holiday pages are intentionally limited because education calendars are often regional. Dedicated pages preserve subdivision or zone information and recommend official local verification for critical dates.