Time & Date · Timestamps
Date-Time Format Converter
Paste a date or timestamp in almost any format — ISO 8601, RFC 2822, Unix seconds or milliseconds, Excel serial numbers, 15/01/2026 or Jan 15, 2026 — and get it in every other common format, in any time zone.
Your inputs
Quick start — try a typical case
Your result Live
ISO 8601 in UTC
2026-10-11T13:00:00Z
Sunday 11 October 2026, 01:00 PM
- ISO 8601 (UTC)
- 2026-10-11T13:00:00Z
- RFC 2822 (email)
- Sun, 11 Oct 2026 13:00:00 +0000
- HTTP Date (always GMT)
- Sun, 11 Oct 2026 13:00:00 GMT
- Unix Seconds / Milliseconds
- 1791723600 / 1791723600000
- Excel Serial Date (local)
- 46306.541667
- India / UK (DD/MM/YYYY)
- 11/10/2026 13:00:00
- US (MM/DD/YYYY)
- 10/11/2026 01:00:00 PM
- SQL DATETIME
- 2026-10-11 13:00:00
- ISO Week Date / Ordinal Date
- 2026-W41-7 / 2026-284
- Julian Date (astronomy)
- 2461325.04167
Shown in UTC (UTC+00:00); the input was read as Asia/Kolkata where it had no offset.
How this is calculated
Excel serial = days since 30 Dec 1899 (+ time as a fraction) · Julian Date = Unix ms ÷ 86,400,000 + 2,440,587.5
- ISO 8601
- YYYY-MM-DDTHH:MM:SS±HH:MM — the international standard; 'Z' means UTC
- RFC 2822
- The format used in email headers, e.g. Sun, 11 Oct 2026 18:30:00 +0530
The converter first works out the exact moment your text refers to — using its offset if it has one, otherwise the time zone you choose — and then writes that moment in each format. Numeric dates are ambiguous (01/02/2026 is 1 February in India and January 2 in the US), so choose which order your dates use.
Assumptions & sources
- Excel serial dates use the 1900 date system (Windows Excel); dates before 1 March 1900 differ in Excel because of its historic leap-year bug.
- Leap seconds aren't represented (as in Unix time).
- 1RFC 3339 — Date and Time on the Internet: Timestamps — IETF
- 2RFC 5322 — Internet Message Format (date-time) — IETF
- 3ISO 8601 — Date and time format (week numbering, calendar dates) — International Organization for Standardization
- 4Calendrical Calculations (Reingold & Dershowitz) — Cambridge University Press
Calculator ID TIME-FORMAT-001 · version 1.0.0
Common questions
What is ISO 8601?
The international standard for writing dates and times: year-month-day, 24-hour time and an offset from UTC, e.g. 2026-10-11T18:30:00+05:30. It sorts correctly and isn't ambiguous.
How do Excel dates work?
Excel stores a date as the number of days since 30 December 1899 (so 1 January 1900 is 1), with the time of day as the fraction — 46306.5 is midday on 11 October 2026.
Why does 01/02/2026 give two answers?
Day-first (India, UK, Europe) reads it as 1 February; month-first (US) as January 2. Choose the order under 'Numeric Dates Are'.