Date Converter
Converts a date between many formats — Unix timestamps, ISO 8601, RFC 3339, RFC 7231, UTC, locale strings, Excel serial numbers and Mongo ObjectIDs.
Convert between date formats online — ISO 8601, RFC 3339, UTC, locale, Excel, Mongo ObjectID and Unix timestamps.
Steps and notes
What is Date Converter — Formats, Time Zones and ISO 8601?
A single moment in time wears many coats, and this tool converts between all of them: Unix timestamps (seconds or milliseconds), ISO 8601, RFC 3339 and RFC 7231 strings, UTC, your locale-formatted string, the Excel serial number (days since 1900-01-01), and the leading 4-byte timestamp embedded in a Mongo ObjectID. Where a format names no timezone, your browser local zone is applied — so "now" on this page may read a different wall-clock than a UTC log line for the same instant. Everyday uses: turning a timestamp from a log or database field into a readable local time, checking whether an expiry (a JWT exp, a cache TTL, a Mongo-created document) is already in the past, and generating values for test fixtures.
- Use the current time or enter one manually
- Read the Unix timestamp and the formatted results
- Note whether you need seconds or milliseconds
- Unix timestamps are usually seconds (10 digits), while JavaScript Date.now() is milliseconds (13 digits)
Frequently asked questions
- Is my timestamp in seconds or milliseconds?
- Count the digits: 10 digits is seconds (good until the year 2286), 13 digits is milliseconds. Pasting seconds where milliseconds are expected lands you centuries in the future — the wrong scale is usually obvious as soon as you convert.
- Why does the converted time shift by hours?
- Timezone interpretation. ISO strings like 2026-10-05T08:00:00Z name an exact moment (Z = UTC), but "2026-10-05 08:00" without a zone is ambiguous and gets read as your local time. A +8h shift almost always means one side treated a zone-less string as UTC and the other as local.
- Which timestamp format should I store in my database?
- Either UTC ISO 8601 strings or integer Unix timestamps — both are unambiguous. What you must avoid is zone-less datetime strings in local time: they break the moment a server, a user or daylight saving changes the timezone.
Category: Converter
JWT tools workflow
JWT Decoder & Parser — Inspect Header, Payload and Expiration → Base64 Encoder & Decoder — Padding, URL-Safe, Binary-Safe → Date Converter — Formats, Time Zones and ISO 8601 → Unix Timestamp Converter — Epoch to Date, Seconds vs Milliseconds