Toolarithm

Unix Timestamp Converter

Unix Timestamp Converter

Convert Unix timestamps in seconds or JavaScript milliseconds into UTC and common timezone views. Also convert an ISO date-time string back into Unix seconds and milliseconds.

Live converter

Unix timestamp inputs

Convert Unix seconds or JavaScript milliseconds into UTC and local time displays.

UTC date-time

2026-06-10T12:00:00.000Z

Timestamp comparison table

ViewValueNote
UTCWed, Jun 10, 2026 12:00UTC+00:00
DubaiWed, Jun 10, 2026 16:00UTC+04:00
New YorkWed, Jun 10, 2026 08:00UTC-04:00
ISO input seconds1781092800From ISO field
ISO input milliseconds1781092800000From ISO field

Epoch

1970-01-01 UTC

Units

seconds + ms

Views

UTC + zones

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What Can You Create?

Convert timestamps for logs, APIs, databases, and debugging

Timestamp debugging

Translate Unix seconds and JavaScript milliseconds into readable UTC and timezone-specific values.

Full comparison table

Review surrounding units or time zones after the selected result, reducing repeated input for adjacent checks.

Formula-backed output

Use visible method notes to understand how the result was produced before copying it into another workflow.

Formula

Unix timestamp conversion formula

Unix timestamps count elapsed time from the Unix epoch at 1970-01-01 00:00:00 UTC. JavaScript Date values use milliseconds.

Working formulas

Seconds to milliseconds

milliseconds = Unix seconds x 1000

JavaScript Date constructors use milliseconds.

Milliseconds to seconds

Unix seconds = floor(milliseconds / 1000)

Unix timestamp APIs often store seconds.

Epoch

0 = 1970-01-01T00:00:00Z

The timestamp is measured from midnight UTC at the Unix epoch.

Symbols

Unix seconds - timestamp seconds
Whole seconds elapsed since the Unix epoch.
JS milliseconds - Date time value
Milliseconds elapsed since the same UTC epoch.
Conversion Guide

Epoch units, offsets, and unambiguous timestamps

This is a two-way instant converter rather than a date-format reference chart. It maps Unix seconds or ECMAScript milliseconds to the same UTC instant, then shows timezone views without changing the underlying moment.

Seconds, milliseconds, and the epoch

Unix time uses the epoch at 1970-01-01T00:00:00Z. Multiplying whole Unix seconds by 1,000 gives the corresponding ECMAScript millisecond value exactly; dividing milliseconds and taking the floor gives the whole-second timestamp used by this page.

POSIX represents each accounted day as 86,400 seconds and does not assign an additional timestamp value to an inserted leap second. Timezone rows are presentation views of the resulting instant, not independent local timestamps.

Worked conversion: the start of 2024 UTC

1,704,067,200 s x 1,000 = 1,704,067,200,000 ms

Both values resolve to 2024-01-01T00:00:00.000Z. The trailing Z is important: it states that the ISO value is UTC rather than an offset-free local wall time.

Preserve unit and offset

A 10-digit contemporary timestamp is commonly seconds, while a 13-digit value is commonly milliseconds, but digit count is only a clue. Copy the explicit unit with the number so another system does not shift the date by a factor of 1,000.

For reverse conversion, prefer an RFC 3339-style date-time with Z or an explicit numeric offset. An offset-free string can be interpreted using local assumptions, and fractional milliseconds may not survive a whole-second export.

Use this page to debug one stored instant. Use the timezone meeting planner when the task starts with a future local meeting time and requires city-by-city wall-clock views.

Plan a local meeting across time zones

Limits to keep with the result

  • The converter follows the host ECMAScript Date range and parsing behavior; systems with narrower timestamp ranges may reject otherwise valid values.
  • Leap seconds are not represented as extra POSIX timestamp counts in this model.
  • Timezone rules can change over history, so preserve the UTC instant when exchanging data across systems.
Why Users Love This Tool

Why timestamp units need clear labels

Seconds and milliseconds together

  • Unix APIs commonly use seconds, while JavaScript Date values use milliseconds.
  • The converter labels both units so users do not accidentally shift a date by a factor of 1000.
  • ISO input conversion helps check expected timestamps before saving values into systems.

UTC first

  • The primary result is an ISO UTC timestamp, which is the safest value for debugging.
  • Timezone rows are displayed as views of the same instant, not separate moments.
  • Offsets remain visible for quick inspection across regions.
Perfect For

Built for technical time debugging

Developers

Convert API timestamps, log fields, queue events, and database values into readable times.

Analysts

Check whether imported timestamp fields are seconds, milliseconds, or ISO strings.

Ops teams

Compare event timestamps across UTC, Dubai, New York, and other operational contexts.

How It Works

How it works in three quick steps.

1

Enter the timestamp

Paste a Unix timestamp and choose whether it is seconds or JavaScript milliseconds.

2

Read UTC and timezone views

Review the ISO UTC date and the table of local-time views.

3

Convert ISO back to timestamp

Use the ISO field to calculate Unix seconds and milliseconds for a known date-time string.

Download & Print

Save timestamp conversions

Copy result

Copy the selected conversion with labels so the result can move into tickets, docs, worksheets, or chat.

Print the table

Print the full table when a task needs repeated comparisons across related units or time zones.

Keep the formula visible

Use the formula notes to explain whether the result came from a factor, an offset, or a timezone rule.

FAQ

Frequently Asked Questions

What is a Unix timestamp?
A Unix timestamp counts elapsed time since 1970-01-01 00:00:00 UTC. Many APIs and databases store timestamps as whole seconds, while JavaScript Date values use milliseconds from the same epoch.
Why does JavaScript use milliseconds?
JavaScript Date time values are represented in milliseconds since the epoch. That means a Unix seconds value usually needs to be multiplied by 1000 before it is passed into a JavaScript Date constructor.
What happens if I mix seconds and milliseconds?
Mixing units shifts the date by a factor of 1000. A seconds value treated as milliseconds will appear near 1970, while a milliseconds value treated as seconds can appear thousands of years in the future.
Should timestamps be stored in UTC?
UTC is usually the safest storage representation for logs, APIs, and databases. Local time zones should generally be display views of the same instant, because timezone offsets can change with daylight saving and regional rules.
Can Unix timestamps represent dates before 1970?
Yes. Negative timestamp values represent instants before 1970-01-01 00:00:00 UTC. Support can vary by system, but the mathematical representation allows negative elapsed seconds or milliseconds.
About This Tool

About this Unix timestamp converter

Timestamp bugs often come from unit mismatch. A value may be Unix seconds in one API, JavaScript milliseconds in a browser, and an ISO string in a database export. This converter keeps those forms visible together.

UTC is shown first because it is the cleanest debugging reference. Local-time rows are useful for human interpretation, but they are displays of the same instant rather than separate stored values.

The ISO input field supports the reverse workflow: start with a known date-time string and calculate the seconds or milliseconds needed for a system field.

Editorial Transparency

Who maintains this page

Ownership and review

Written and maintained by the Toolarithm editorial team. No review date is shown without a maintained editorial record. No independent professional review is claimed.

Methodology

Conversion factors are normalized to canonical units and checked in both directions. Exact definitions and offset formulas are preferred over rounded lookup values.

Read the editorial methodology

Dates and sources

Review dates change only after a substantive method or content check.

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