---
title: "Unix timestamp converter — free, runs in your browser"
description: "Convert between Unix timestamps and human dates, in seconds or milliseconds. Free, no sign-up, and nothing you enter leaves your browser."
url: https://atoneplace.net/tools/unix-timestamp-converter/
site: "At One Place"
---

# Unix timestamp converter

Convert between Unix timestamps and human dates, in seconds or milliseconds.

## How it works

Converts a Unix timestamp to a readable date and back, handling both seconds and milliseconds, in local time and UTC.

Seconds versus milliseconds is the error that catches everyone. Unix time is defined in seconds since 1 January 1970 UTC, but JavaScript, Java and several databases use milliseconds. A timestamp misread by that factor of a thousand lands in 1970 or in the year 55000, which is at least obvious — the subtle version is a value that is plausible in both, and the tool guesses by magnitude and says which it assumed.

Unix time deliberately ignores leap seconds, so it is not a true count of elapsed seconds. A leap second is represented by the same value repeating, which is why some systems briefly see time run backwards during one.

The 2038 problem is real but narrowing: a signed 32-bit timestamp overflows on 19 January 2038. Most modern systems use 64-bit values, which last about 292 billion years, but embedded and legacy code still carries the limit.

> This tool runs entirely in your browser. Nothing you enter is sent to a server, logged or stored, and the page keeps working with the network disconnected.

## Common questions

### Is a Unix timestamp in seconds or milliseconds?

The standard is seconds since 1 January 1970 UTC, but JavaScript and Java use milliseconds. A ten-digit number is seconds; thirteen digits is milliseconds.

### What is the 2038 problem?

A signed 32-bit timestamp overflows on 19 January 2038. Modern systems use 64-bit values, but embedded and legacy code can still hit it.

### Does Unix time include leap seconds?

No. It ignores them by definition, so it is not a true elapsed-second count. A leap second repeats a value, which can make time appear to go backwards.

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## Sources

- Calculated on this page — At One Place (/about/)