1. Astronomical and Calendar Standards
All calculations on TimeAndDateCalculator.com strictly implement the international standard ISO-8601:2019 (Data elements and interchange formats – Information interchange – Representation of dates and times) and the proleptic Gregorian calendar.
Leap Year Rules
Under the Gregorian calendar reform of 1582, a year has 365 days, with an extra leap day added to February in leap years. Our calculation engine verifies leap years using the full three-tier algorithm:
function isLeapYear(year) {
return (year % 4 === 0 && year % 100 !== 0) || (year % 400 === 0);
}
2. Time Zone and Daylight Saving Time (DST)
Timezone conversions are powered by the native Intl.DateTimeFormat API, utilizing the IANA Time Zone Database (Olson Database), maintained by ICANN. This ensures that historical changes in daylight saving time and government-mandated offset adjustments are handled accurately.
3. 100% Client-Side Execution & Privacy
Unlike tools that send your date queries to remote servers for processing, every single calculation on TimeAndDateCalculator.com is executed directly inside your local web browser. Your confidential personal dates, employee shift logs, and contractual deadlines never leave your computer or phone.