Unix Timestamp Converter

Convert seconds, milliseconds, microseconds, and nanoseconds to dates. Work with time zones, local CSV batches, and time calculations.

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Convert Timestamps And Dates

Use Convert for a Unix value, an ISO date, or a supported RFC 2822-style date. Choose the numeric unit and time zone, then copy the result you need. Seconds, milliseconds, microseconds, and nanoseconds are converted with exact decimal arithmetic within the supported date range.

For example, 1700000000 seconds and 1700000000000 milliseconds both identify 2023-11-14T22:13:20Z. Auto detection is a convenience; select the documented unit yourself when working with historical dates, small values, or an API field with a known unit.

Batch Conversion And Time Calculations

Use Batch to paste one value per line or import TXT, CSV, and TSV files. Choose the delimiter, header setting, and timestamp column for delimited files. Review individual errors before exporting CSV, TSV, or JSON. Each run is limited to 10,000 records and 2 MiB of input, with up to 256 columns per CSV record and 512 characters per timestamp value.

Use Calculate to compare two instants or add and subtract time. Calendar days follow the selected time zone; elapsed hours, minutes, and seconds measure a duration. The current-time display can be paused and copied, and date shortcuts provide day, month, and year boundaries.

Local Processing

Conversion, calculations, file reading, and export run in this browser. Tool inputs and imported files are not uploaded for processing, and the tool does not save your input by default. Download an export if you need to keep the results. The website still loads page resources and analytics; local processing does not mean the page makes no network requests.

Units, Formats, And Time Zones

Why does my timestamp turn into a date in 1970?

A common cause is reading seconds as milliseconds: 1700000000 milliseconds is in January 1970, while the same number of seconds is in November 2023. Check the source unit instead of adding or deleting zeros by guesswork. JWT exp, nbf, and iat use seconds since the Unix epoch; JavaScript Date.now() returns milliseconds. Converting a JWT date does not verify the token or its signature.

Which date strings can I enter?

Use an ISO date-time such as 2023-11-14T22:13:20.123456789Z, or a common RFC 2822-style value such as Tue, 14 Nov 2023 22:13:20 +0000. This is a strict parser, not a natural-language date interpreter. For an ISO date-time without an offset, select the time zone in which that clock reading occurred. An explicit Z or numeric offset identifies the instant directly.

Why is the displayed date eight hours different?

UTC and Asia/Shanghai display the same modern instant eight hours apart. Changing the display time zone does not change its Unix value. Choose UTC, your browser local zone, or an IANA name such as Asia/Shanghai or America/New_York. For an input without an offset, the selected zone determines how that local clock reading becomes an instant.

What do Reject, Earlier, and Later mean?

A daylight-saving transition can repeat a local time or skip it entirely. Reject reports these cases so you can check the source. Earlier or Later explicitly selects an interpretation; for a skipped time, that can move the displayed clock time across the gap. Use an explicit offset when you know which occurrence was intended. See Temporal time-zone disambiguation.

Does nanosecond output mean a nanosecond-accurate clock?

No. Converting an exact input can preserve its nanosecond digits, but the live current-time value comes from a millisecond-based browser clock, which may be rounded further by privacy settings. Extra microsecond or nanosecond digits are zero padding, not new measurements. RFC 2822 output shows whole seconds and omits the fractional part; use ISO or numeric output to keep subseconds. Unix time does not provide a separate timestamp for a leap second.

Batch Files And Calculations

How should I prepare a batch?

For plain text, put one timestamp or date on each line. For CSV, select the delimiter, indicate whether the first record is a header, and choose the column to convert. Keep a numeric timestamp column as text in spreadsheets so a 19-digit nanosecond value is not rounded before import. The limits are 10,000 records and 2 MiB; split larger inputs before loading them.

What happens to invalid records?

A conversion error stays attached to its record instead of silently removing that row. Review the results and errors before exporting CSV, TSV, or JSON. A successful conversion confirms that the value can be interpreted under the selected settings; it does not confirm that the source supplied the correct unit or time zone.

Is adding one day the same as adding 24 hours?

Not always. A calendar day follows the selected time zone and can span 23 or 25 hours across a daylight-saving change. Use calendar days when you mean the next local date, and elapsed hours when you mean a fixed duration. A day in the time-difference result always means 24 elapsed hours, not the number of local midnights crossed. Review the resulting offset when calculating across a clock change.

Code Examples And References

JavaScript: seconds to an ISO date

const seconds = 1700000000;
new Date(seconds * 1000).toISOString();

JavaScript Date uses milliseconds. Do not pass a 19-digit nanosecond integer through Number and expect every digit to survive. Date documentation.

Python: seconds to an aware UTC datetime

from datetime import datetime, timezone
datetime.fromtimestamp(1700000000, timezone.utc)

Python datetime has microsecond resolution. This whole-second example does not demonstrate nanosecond preservation. datetime documentation.

Go: seconds and nanoseconds to UTC

// import "time"
t := time.Unix(1700000000, 123456789).UTC()
t.Format(time.RFC3339Nano)

The arguments are seconds and a nanosecond adjustment. time.Unix documentation.

Timestamp and date-format references

RFC 7519 NumericDate defines the seconds-based values used by JWT claims. RFC 5322 date-time documents the mail-date format commonly called RFC 2822. This tool accepts a strict subset rather than every historical mail-date syntax. Date.now() explains the browser clock and possible reduced precision.