Calendar edge cases
Leap years, month-end dates and February 29 use calendar arithmetic rather than rough month averages when the task requires exact dates.
Accuracy & methodology
Each tool identifies whether its output is mathematically exact, standard-based, externally published or approximate.
Time-zone rules
Named IANA zones are evaluated for the selected date. Nonexistent local times are rejected and repeated times require an occurrence choice.
Automated regression coverage
TimeNivo uses automated checks for core calculations, routes, security, and SEO. Browser and device coverage is verified separately.
Limitations
Browser time-zone databases, external holiday data and approximate models can differ by version, region or real-world conditions.