Seamlessly convert between ISO 8601 date-time strings, Unix timestamps, and human‑readable formats. Parse any valid ISO 8601 string into its constituent components, generate ISO 8601 from a date picker, and explore timezone offsets. Built for developers, data engineers, and system integrators who demand precision.
ISO 8601 is the international standard for representing dates and times. Published by the International Organization for Standardization (ISO), it provides a clear, unambiguous, and machine‑readable way to express temporal data. The standard covers calendar dates, times of day, time intervals, recurring time intervals, and durations.
Basic format: YYYY-MM-DD · Extended: YYYY-MM-DDThh:mm:ss±hh:mm
Examples: 2026-06-24 · 2026-06-24T15:30:00Z · 2026-06-24T15:30:00+08:00
The standard defines several representations:
YYYY-MM-DD (e.g., 2026-06-24).
YYYY-DDD (e.g., 2026-175 for June 24).
YYYY-Www-D (e.g., 2026-W26-3 for Wednesday of week 26).
hh:mm:ss[.sss] (e.g., 15:30:00.123).
YYYY-MM-DDThh:mm:ss[.sss]±hh:mm or Z for UTC.
P[n]Y[n]M[n]DT[n]H[n]M[n]S (e.g., P1Y2M3DT4H5M6S).
Adopted globally in software development, database systems, APIs (REST, GraphQL), logging, financial transactions, and scientific data exchange, ISO 8601 eliminates the ambiguity inherent in regional date formats (e.g., MM/DD/YYYY vs. DD/MM/YYYY). Its lexicographical ordering property — YYYY-MM-DD strings sort chronologically — makes it ideal for filenames, database keys, and time‑series data.
The converter uses the JavaScript Date object and the Intl.DateTimeFormat API, which natively support ISO 8601 parsing and formatting. When you enter a string, the engine attempts to parse it as a valid ISO 8601 date‑time. If successful, it extracts each component and computes derived values such as day of the year, week number, and weekday. The generation path builds a Date object from the selected date, time, and timezone, then outputs the same set of formats.
For timezone handling, we apply the offset you choose (or your local system offset) to produce the correct UTC equivalent. This ensures that 2026-06-24T15:30:00+08:00 and 2026-06-24T07:30:00Z represent the same instant in time.
Supported formats: Our tool is designed to handle the most common ISO 8601 variants used in practice:
YYYY-MM-DD
YYYY-MM-DDThh:mm:ssZ
YYYY-MM-DDThh:mm:ss±hh:mm (also ±hhmm and ±hh)
YYYY-MM-DDThh:mm:ss.sssZ or with offset
2026-06-24T15:30:00), it is interpreted as local time in your system's timezone. For UTC, always append Z or an explicit offset.
Please note: Week dates (e.g., 2026-W26-3) and ordinal dates (2026-175) are not supported by this version. If you enter such a string, the tool will display a clear error message. We plan to add these in a future release based on user feedback.
The tool has been tested against hundreds of valid and invalid ISO 8601 strings, including edge cases such as leap seconds (though JavaScript's Date does not support leap seconds, so they are ignored) and year 0000. For authoritative reference, we have cross‑checked our implementation against the official ISO 8601:2019 standard and the RFC 3339 specification.
| Format | Example | Description |
|---|---|---|
| Calendar Date |
2026-06-24
|
Basic date with hyphens (interpreted as UTC). |
| Date & Time (UTC) |
2026-06-24T15:30:00Z
|
UTC time with 'Z' designator. |
| Date & Time (Offset) |
2026-06-24T15:30:00+08:00
|
With explicit timezone offset (also supports +0800, +08). |
| Date & Time (Milliseconds) |
2026-06-24T15:30:00.123Z
|
With fractional seconds. |
| Date & Time without offset |
2026-06-24T15:30:00
|
Interpreted as local time (system timezone). |
| Week Date |
2026-W26-3
|
Not supported – will produce an error. |
| Ordinal Date |
2026-175
|
Not supported – will produce an error. |
| Duration |
P1Y2M3DT4H5M6S
|
Not supported – planned for future. |
A global e‑commerce platform operates data centres in Singapore (+08:00), London (+00:00), and New York (-05:00). To unify order timestamps, the engineering team adopted ISO 8601 with UTC (Z) as the canonical format. When an order is placed in Singapore at 15:30 local time, the backend records 2026-06-24T07:30:00Z. This converter helps developers quickly verify that timestamps are correctly normalized. Using our tool, they can paste the UTC string, see the local time in each timezone, and generate the equivalent offset formats for regional reports. The result: zero ambiguity, seamless debugging, and audit‑ready logs.
T as the separator and allows a space as an alternative. Our tool outputs both.
Tue, 24 Jun 2026 15:30:00 +0800). It is human‑readable but less machine‑friendly than ISO 8601.
Date and Last-Modified headers; based on RFC 7231.
ISO 8601 is the recommended choice for data interchange because it is unambiguous, sortable, and self‑describing.
Z) and convert to local time only for display. This avoids daylight‑saving and timezone‑related bugs.
Z. Otherwise, the receiver may misinterpret the value.
-) and colons (:) for readability. The basic format (YYYYMMDDThhmmss) is less human‑friendly.
2026-06-24T15:30:00), the tool interprets it as local time using your system's timezone. This may not be what you expect if you intended UTC. To avoid confusion, always append Z for UTC or an explicit offset when possible.
2026-06-24T15:30:00Z is exactly the same as 2026-06-24T15:30:00+00:00.
T separator and permits a space as an alternative. It also mandates a four‑digit year and a timezone offset. Our tool generates both ISO 8601 and RFC 3339 outputs.
Date engine, which is highly accurate for all valid ISO 8601 strings within the range of ±100,000,000 days from the Unix epoch. Fractional seconds are supported down to millisecond precision, which is sufficient for most applications.
P1Y2M3DT4H5M6S) is not implemented in this version, but may be added in a future update based on user demand.
YYYY-MM-DD, YYYY-MM-DDThh:mm:ss (with optional milliseconds), with Z or an offset like +08:00, -05:00, and also +0800 and +08. We do not currently support week dates (YYYY-Www-D), ordinal dates (YYYY-DDD), or durations. If you enter one of these, the tool will show a clear error message. We are evaluating demand for these features.
2026-06-24+08:00).
Date object does not support leap seconds; they are ignored (the time is rounded down). For most applications, this is acceptable because leap seconds are rarely used in general date‑time handling.