⏱️ Timestamp Converter ☆

Overview

Our Free Timestamp Converter is a free online developer utility that instantly converts Unix timestamps (epoch time) to human-readable dates and vice versa, right in your browser. Unix timestamps are the universal way computers track time, counting seconds since January 1, 1970 (UTC). Our tool converts both second-level (10 digits) and millisecond-level (13 digits) timestamps. Simply paste a Unix timestamp, and it is instantly converted to a human-readable date and time in your local timezone, with options to display in UTC and ISO 8601 format. Conversely, you can select any date and time to generate its corresponding Unix timestamp. The tool automatically detects your browser's timezone and shows the local time alongside UTC for clarity. All conversion happens entirely in your browser. Your timestamps never leave your device. Perfect for developers debugging API responses, system administrators parsing log files, data analysts processing time-series data, and anyone working with epoch-based timestamps. No downloads, no sign-up, no data collection.

How Unix time works

Unix time counts seconds since 1 January 1970 00:00 UTC, ignoring leap seconds, which is why it is the same instant everywhere on Earth. The converter accepts 10-digit second timestamps and 13-digit millisecond timestamps, converts to local time, UTC and ISO 8601, and can also turn a picked date back into a timestamp. Watch the unit: seconds and milliseconds differ by a factor of 1000, and mixing them is the most common bug when reading API responses and logs.

Technical specifications

Property	Timestamp converter behavior
Input	Unix seconds (10 digits) or milliseconds (13 digits), or a date/time
Output	Local time, UTC and ISO 8601, plus the opposite conversion
Timezone	Browser timezone detected automatically, UTC always shown
Epoch	1 January 1970 00:00:00 UTC, leap seconds ignored
Processing	100% client-side JavaScript, nothing transmitted
Cost	Free, no account, no ads

Privacy: timestamps stay in the browser

Log lines and API payloads often contain internal identifiers and activity patterns. Conversions run locally: nothing is transmitted, stored or logged, and the page works offline after loading.

Working with epoch values

• 10 digits means seconds, 13 means milliseconds, check before converting.
• Store timestamps in UTC and render local time only in the UI.
• ISO 8601 with an offset avoids ambiguity in logs and APIs.
• Beware of 2038 for 32-bit signed second counters in legacy systems.
• When comparing dates, convert both to the same unit first.

Related: browse the utility tools for UUIDs, hashing and file inspection.

Epoch time, time zones and precision

Unix time counts seconds since 1 January 1970 at 00:00 UTC, ignoring leap seconds, and that single reference point is why it is the lingua franca of logs, APIs and databases. Most systems store seconds; JavaScript and many APIs use milliseconds, and some high-resolution logs use microseconds or nanoseconds. Converting between them is just multiplying by a thousand, but mistaking the unit is the classic bug, a millisecond value read as seconds points to a date in 1970, while a second value read as milliseconds points to a date early in 1970 too, or fails outright. Time zones are the second trap: the epoch value is always UTC, while a displayed date is local, so the same timestamp can be two different calendar days depending on the viewer. Daylight saving transitions add another edge case, because a local hour can be skipped or repeated. A 32-bit signed counter overflows on 19 January 2038, which is why new systems should store 64-bit values. When reading logs, always confirm whether the number is seconds or milliseconds and whether it is UTC; when writing APIs, prefer ISO 8601 strings for human-facing data and epoch integers for machine comparisons. The converter runs in your browser and stores nothing.