Timestamp Converter

Convert Unix timestamps and dates with explicit units, UTC, batch errors and CSV downloads.

Convert one time or a list. Choose seconds or milliseconds explicitly; every result includes an exact UTC date. Your values stay in this tab.

Convert

Input unit

Unix timestamps

One value per line · up to 1,000 non-empty lines and 100,000 characters. Units are never guessed. Fractional milliseconds, exponents and commas are rejected.

UTC range: years 0001–9999. Precision: one millisecond. Invalid calendar dates are rejected; leap seconds and named timezones in date input are unsupported. Blank lines are skipped.

This tool runs entirely in your browser. Your data is never uploaded, never stored, and never leaves your device.

Convert Unix seconds or milliseconds and explicit dates, review batch errors, and export results with unambiguous UTC handling.

How to use it

1Choose timestamps or dates and specify the input unit.
2Paste one value or one value per line, then convert.
3Review UTC results and any row errors before copying or downloading CSV.

What happens to your data

Dates and log values are processed in your browser and are not placed in a public URL. Dates without a timezone are explicitly interpreted as UTC.

Last updated October 2026

Convert Unix timestamps into dates, or turn explicit calendar dates back into epoch time. Choose seconds or milliseconds yourself instead of relying on a guess based on the number of digits. Paste one value or a list, review individual results, and export a local CSV when you are comparing application logs or data exports.

Unix time counts elapsed time from 1970-01-01T00:00:00Z. The timestamp identifies an instant; UTC and a local timezone are different ways to display that same instant. This converter treats a date without a timezone as UTC, explicitly, so two colleagues in different countries do not silently get different answers from the same input. Include Z or a numeric offset when copying dates from another system.

How it works

Seconds can include a fraction down to millisecond precision; milliseconds are whole numbers. Zero is valid, and negative values represent instants before the epoch. Unsupported precision is rejected rather than silently rounded. Calendar input is checked before conversion, so an impossible date such as February 30 cannot roll forward into March unnoticed. Supported UTC dates run from year 0001 through 9999. A batch is limited to 100,000 characters and 1,000 non-empty lines.

Batch conversion reports an error on the affected row instead of hiding it or shifting the remaining rows. Review the results before using the CSV. Blank input is not interpreted as today. A browser-local display is provided as context, while the UTC result remains the portable reference. This is an instant converter, not a recurring schedule planner: an offset such as +05:30 does not describe a timezone's future daylight-saving rules.

Processing stays on your device. The page does not fetch a time service, upload log lines, or place the input in a sharing URL. Unix timestamps do not encode a leap-second table, and this tool does not accept GPS time, Excel date serials, .NET ticks or nanosecond epochs as if they were Unix seconds.

Worked example: distinguish one second from one millisecond

Input: 1 with the unit Seconds; 1 with the unit Milliseconds
Result: 1970-01-01T00:00:01.000Z; 1970-01-01T00:00:00.001Z

The same digits mean different instants when the input unit changes.

Common use cases

Reading seconds or milliseconds in API responses
Comparing a batch of log timestamps in UTC
Checking a date with an explicit numeric timezone offset
Exporting reviewed timestamp conversions to CSV

Frequently asked questions

Are Unix timestamps seconds or milliseconds?＋

The original Unix convention counts seconds, while many browser and application APIs use milliseconds. Select the unit documented by the source. A length heuristic can be wrong for old dates or future values, so this tool does not silently choose for you.

What happens when my date has no timezone?＋

This tool interprets it as UTC. To describe another instant, include Z for UTC or an explicit offset such as +05:30. Local browser time is labelled separately and is not the default interpretation of an unzoned date.

Can I convert multiple timestamps at once?＋

Yes. Paste one input per line, choose the input type and review the batch results. Invalid entries retain their own row and error message. Download the reviewed results as CSV.

Why is my date rejected rather than adjusted?＋

Silent adjustment can hide bad source data. Impossible calendar dates, unsupported fractions and values outside the supported date range are errors. Correct the input rather than relying on automatic rollover.

Does this handle daylight saving and leap seconds?＋

Explicit offsets describe the supplied instant. They do not predict future daylight-saving changes, and Unix time does not represent leap seconds as a separate normal second. Use a timezone-aware scheduling system for recurring local events.