Unix Timestamp Converter
Convert Unix seconds or milliseconds to dates and dates to timestamps. Your input stays in your browser.
- Free, no sign-up
- Text stays in your browser
- Local processing / no upload
Limit: 500,000 character units per input. Oversized pastes are rejected. Drafts stay in this page and are not saved.
For dates, use YYYY-MM-DD or YYYY-MM-DDTHH:mm:ss with optional milliseconds. Omit timezone suffixes; UTC or Local below applies.
Step by step
How to use Unix Timestamp Converter
Step 1: Choose the conversion direction and explicit seconds or milliseconds units. For date entry, choose UTC or your browser local timezone.
Step 2: Enter the timestamp or a date such as 2024-02-29T12:34:56.789, without a timezone suffix. Select Convert timestamp.
Step 3: Check both the ISO UTC result and local display. Use current time fills the input using your selected mode but does not automatically convert it.
Example to try
Enter 1.001 with Seconds selected. The result represents 1001 milliseconds after the epoch and shows UTC 1970-01-01T00:00:01.001Z. Local display depends on your browser timezone.
Choose timestamp units explicitly
Unix timestamps measure elapsed time from 1970-01-01 at midnight UTC. This tool requires an explicit choice between seconds and milliseconds so a short or long value is not silently guessed. Timestamp 0 corresponds to the epoch. Negative values represent dates before it. Output includes the selected-unit value, both Unix unit representations, an ISO UTC date and the browser's local date display.
Convert calendar dates with a labeled timezone
Date entry accepts YYYY-MM-DD or a date followed by T or a space and HH:mm, with optional seconds and up to three fractional-second digits. UTC is the default interpretation; Local uses the current browser timezone. Omit a timezone suffix because the selected control defines the interpretation. Invalid calendar dates, overflowing fields and nonexistent local times are rejected instead of rolling into a different date.
Output limits and local processing
Values must resolve to whole milliseconds within the supported date range. The tool does not handle leap seconds, time-zone databases for other cities or historical calendar systems. Local times near daylight-saving changes can be ambiguous; use UTC when an unambiguous instant is required. Review the generated ISO date and units before pasting a timestamp into an API or database.
Inputs and results are held only in this page's memory. Developer inputs accept up to 500,000 character units each. Oversized pastes are rejected while preserving the previous input. Generated output is limited to 5,000,000 character units. No sign-up is needed. Copy and download actions are explicit; the tool does not upload your drafts or save them for a later visit.