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Quick guide

What This Calculator Does

If you work with logs, APIs, databases, or frontend-backend debugging, timestamp confusion shows up constantly. The two biggest sources of trouble are usually simple: not knowing whether a number is in seconds or milliseconds, and not knowing whether a date-time input is being treated as UTC or as local time. This timestamp converter is built to help you separate those assumptions quickly.

It converts Unix-style timestamps into readable date-time strings and also converts browser-local date-time input back into a timestamp. You can switch between seconds and milliseconds, which makes it useful for debugging, content verification, API testing, and quick format checks.

When to Use It

  • You want to decode a timestamp from logs, databases, or API payloads.
  • You need to generate a seconds-based or milliseconds-based timestamp from a known date and time.
  • You are checking whether a system uses seconds or milliseconds.
  • You want a quick browser-side validation without opening code.

Inputs Explained

Timestamp

This field expects an integer-style Unix timestamp. The current page interprets it as either seconds or milliseconds based on the selected unit.

As a rough rule, a 10-digit number often means seconds and a 13-digit number often means milliseconds, but it is still smart to verify with the page rather than assume.

Date Time

Frequently Asked Questions

What is the most common mistake this tool helps catch?

The biggest issues are mixing up seconds and milliseconds or assuming the date-time field automatically means UTC.

Does the unit mode affect both directions?

Yes. The selected unit affects both timestamp-to-datetime and datetime-to-timestamp conversion.

Why does the page use separate buttons instead of auto conversion?

Because the current page makes the conversion direction explicit, so you can clearly choose whether you want to read a timestamp or generate one.

Which timezone does the displayed date-time use?

The current page interprets datetime-local input in the browser's local environment and does not append an explicit timezone label.

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Usage Tips

  • Calculation results are for reference only, please adjust according to actual circumstances
  • For important decisions, it is recommended to consult relevant professionals
  • Please verify the accuracy of the results before using them

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Timestamp Converter

Convert between timestamps and datetime, supporting seconds and milliseconds

Timestamp conversion

Convert between Unix timestamps and datetime, with seconds, milliseconds, local time, and UTC ISO shown together.

Common inputs

Conversion direction

Timestamp

Seconds

Timestamp unit

Conversion result

After conversion, this panel shows seconds, milliseconds, local datetime, UTC ISO, and browser timezone.

Ready to convert

After conversion, this panel shows seconds, milliseconds, local datetime, UTC ISO, and browser timezone.

How to use the result

A Unix timestamp is a UTC instant; the datetime input is interpreted in the browser local timezone. Copy UTC ISO when debugging across systems.

Seconds vs milliseconds

10 digits usually mean seconds; 13 digits usually mean milliseconds.

Local timezone

The datetime input is interpreted in your current browser timezone, not UTC.

Debugging logs

Log systems often use UTC ISO strings; copying ISO reduces timezone confusion.