About Epoch Converter

An epoch converter changes Unix timestamps into readable dates and converts dates back into epoch seconds or milliseconds.

This tool shows the current timestamp, handles timezone selection, supports second and millisecond units, and includes quick date arithmetic for adding or subtracting time.

How to use the Epoch Converter

Use the current timestamp panel when you need the live epoch value in seconds or milliseconds.
Paste a timestamp, choose seconds or milliseconds, select a timezone, and convert it to a readable date.
Enter a date and timezone to generate the matching epoch value for APIs, logs, or database queries.
Use the time calculation row to add or subtract years, months, days, hours, minutes, or seconds from now.

When you would use it

Decode API fields such as created_at, expires_at, iat, exp, or event_time while debugging.
Check whether a JWT expiration, cache TTL, or signed URL deadline is already past.
Convert production log timestamps into a local timezone before comparing incidents.
Generate exact test timestamps for frontend fixtures, database filters, or scheduled jobs.

Seconds, milliseconds, and timezones

Unix time counts elapsed time since 1970-01-01 00:00:00 UTC. The same instant can be displayed in many timezones, but the epoch value itself is timezone-independent.

Seconds: usually 10 digits for modern dates, common in Unix tools and many APIs.
Milliseconds: usually 13 digits, common in JavaScript Date.now() and browser logs.
Timezone display: converting a timestamp to Asia/Shanghai or UTC changes the displayed clock time, not the instant.
Date input: ambiguous dates should be written with a full year, month, day, hour, minute, and second when precision matters.

Epoch Converter FAQ

What is an epoch timestamp?: It is a number representing elapsed time since 1970-01-01 00:00:00 UTC, usually in seconds or milliseconds.
How do I know if a timestamp is seconds or milliseconds?: Modern second timestamps are usually 10 digits, while millisecond timestamps are usually 13 digits.
Does timezone change the timestamp value?: No. Timezone changes how the instant is displayed as a calendar date, but the epoch value represents the same moment.
Why is my converted date off by several hours?: The usual cause is reading a UTC timestamp in a local timezone, or mixing seconds and milliseconds.
Is my timestamp data uploaded?: No. Conversion and time calculation run locally in the browser and are not uploaded to wetool.site.

Epoch seconds vs JavaScript dates

JavaScript Date uses milliseconds internally, while many backend systems and command-line tools use epoch seconds. When a converted date looks wildly wrong, checking the unit is the first thing to do.

Timestamp length and unit cheat sheet

Many timestamp bugs are unit bugs, not calendar bugs. Seconds, milliseconds, microseconds, and nanoseconds can all look like plain numbers.

10 digits usually means epoch seconds, such as 1720000000.
13 digits usually means milliseconds, such as JavaScript Date.now().
16 digits often means microseconds and 19 digits often means nanoseconds; divide before displaying them as normal dates.

Timezone debugging checklist

An epoch value represents one instant. Timezones only change how that instant is displayed, so hour offsets usually come from parsing or display assumptions.

Confirm whether the source value is already UTC epoch, not a local date string.
Check whether typed dates include a timezone; bare date strings are often parsed as local time by browsers.
Compare logs in UTC first, then convert to the business timezone such as Asia/Shanghai or America/New_York.