Anatomy of an ISO timestamp
Consider 2026-08-03T08:03:42.878Z. The first part is the calendar date in year-month-day order. The letter T separates the date from the time. The final Z states that the clock reading is in UTC.
Z, offsets, and missing zones
Zmeans UTC.+08:00means eight hours ahead of UTC.-04:00means four hours behind UTC.- No Z or offset means the value is a local clock reading and needs separate time-zone context.
Fractional seconds
The digits after the decimal point represent fractions of a second. In 42.878, the value includes 878 milliseconds. Applications may omit this part or use a different precision depending on their requirements.
Why ISO order is useful
The year-first structure avoids the ambiguity of dates such as 03/08/2026, which different regions may read as March 8 or August 3. Consistently formatted UTC values also sort naturally as text when they use the same precision.
Related time guides
Decode a timestamp
Open Time Zone Converter →