Timestamp Converter

Convert Unix timestamps and dates

A Unix timestamp records elapsed time from 1970-01-01 00:00:00 UTC. This tool converts numeric timestamps to readable dates and lets you turn a date selected in your browser into seconds or milliseconds. Inputs are processed locally.

Seconds or milliseconds?

Modern Unix timestamps are commonly written as 10 digits for seconds or 13 digits for milliseconds. The converter uses the value's magnitude to infer the unit. Multiplying seconds by 1000 gives the corresponding milliseconds.

These examples use UTC so they are independent of your computer's timezone. The current rule treats values below 1,000,000,000,000 as seconds and values at or above it as milliseconds. Timestamp-to-date results must fall between the Unix epoch and 2100-01-01T00:00:00.000Z, inclusive. For an earlier millisecond value such as 946684800000 (the start of 2000 UTC), first divide by 1000 and enter 946684800 seconds; otherwise it is interpreted as seconds and rejected for exceeding the upper limit.

How to use the converter

Timestamp to date

1. Enter a numeric timestamp, or use the current-time button.
2. Choose a readable, ISO 8601 or YYYY-MM-DD HH:mm:ss result.
3. For readable or custom output, select local time or UTC.
4. Convert, inspect the result and copy it when ready.

ISO output always uses UTC and ends in Z. Changing the local/UTC selector does not change an ISO result.

Date to timestamp

1. Select a date and time in the date-time field.
2. Choose seconds or milliseconds for the result.
3. Convert and copy the numeric timestamp.

The date-time field is interpreted in your browser's local timezone. When matching an API event, confirm that the source date and your selected local time describe the same instant.

Local time and UTC

A timestamp identifies an instant; a timezone changes how that instant is displayed. For example, 1640995200 is midnight UTC on January 1, 2022, and 08:00 on the same day in UTC+08:00.

The live clock shows current seconds, milliseconds, local time and ISO time. Your browser supplies local timezone and daylight-saving rules.

Troubleshooting

• The date is far from what you expect: check whether the source uses seconds or milliseconds and whether its value matches the automatic unit heuristic.
• The displayed hour differs: compare UTC with your local timezone. A date-time field without an offset is interpreted as local time.
• An input is rejected: use a numeric, non-negative Unix value within the range accepted by the tool. Dates before the Unix epoch are not accepted by timestamp-to-date conversion.
• Leap seconds: this tool uses JavaScript Date and does not offer a separate leap-second representation.

Work with API data and logs

Use the JSON formatter to inspect an API response containing created_at fields, or the CSV viewer to inspect timestamp columns in an exported table. For changes between two log samples, use text diff.

Common questions

Will changing the timezone change the timestamp?

No. The same instant has the same Unix value. A local date-time entered without an offset can describe a different instant from a UTC date with the same clock digits.

Are seconds and milliseconds interchangeable?

Only after conversion. For the examples above, multiply seconds by 1000 to obtain milliseconds, or divide milliseconds by 1000 to obtain seconds.

Is my input uploaded?

No. The built-in converter processes the input in your browser. This does not change the data practices of external websites linked elsewhere on ToolsVault.

Zero, negative values, and local date input

In UTC, timestamp 0 seconds is 1970-01-01T00:00:00.000Z, and -1 second is 1969-12-31T23:59:59.000Z. Negative Unix values represent instants before the epoch, but this tool's timestamp-to-date input currently rejects them with a too-small-value error. The mathematical example above explains the convention, not an accepted input for that direction.

A datetime-local input has no timezone suffix. The browser interprets it in its local timezone before converting to a timestamp. Daylight-saving transitions can make some local times ambiguous or nonexistent. Use an explicit UTC result when checking a cross-region event. Dates outside the browser's supported range can fail even if the input looks numeric.

You can use the example button below the converter to fill a seconds timestamp and return to the timestamp-to-date tab. Click the conversion button afterward to generate a result.