---
title: "Unix Timestamp Converter"
description: "Convert Unix timestamps (seconds, milliseconds, microseconds, nanoseconds) to human-readable dates and back. Live clock included."
url: "https://freshjuice.dev/tools/timestamp-converter/"
---
## About this tool

Paste any epoch timestamp and get ISO 8601, UTC, and your local time back. The unit is auto-detected from digit length: ~10 digits is seconds, ~13 milliseconds, ~16 microseconds, ~19 nanoseconds. ISO date strings work too.

Leave the input empty and the tool shows the current time, updating every second — useful when you just need "now" in epoch form for a log line or an API call.

## Common pitfalls

-   **Seconds vs milliseconds** — JavaScript's`Date.now()` returns milliseconds; most server APIs expect seconds. Off-by-1000 timestamps land in 1970 or the year 56000.
-   **Time zones** — epoch values are always UTC. The conversion to a calendar date depends on the zone you display it in.

## Frequently Asked Questions

### How does the tool know if my timestamp is in seconds, milliseconds, or nanoseconds?

Digit length. Epoch seconds are ~10 digits today, milliseconds ~13, microseconds ~16, nanoseconds ~19. The tool auto-detects from the length and converts. If it guesses wrong (say, a 13-digit value that's really microseconds from a niche API), you'll get a date in 2001 or the far future and can fix the input by hand.

### Why does my timestamp convert to 1970?

You passed milliseconds where seconds were expected, so the date lands shortly after the epoch. The reverse mistake, seconds into a millisecond field, produces dates in the year 50000. Check which unit your API actually wants: JavaScript's `Date.now()` returns milliseconds, while most Unix tools and JWT claims use seconds.

### What time zone does the converter use?

Epoch timestamps are absolute: they encode a single moment with no time zone. The converter shows ISO 8601 in UTC plus your browser's local time. Both are the same instant, just written differently, so there's no time zone offset applied to the raw number.

### What's the difference between Unix time and ISO 8601?

Unix time counts seconds since 1970-01-01T00:00:00Z (skipping leap seconds): one number, easy to store and compare. ISO 8601 (`2026-08-29T18:49:05Z`) is the human-readable calendar version with an explicit offset. The tool goes both directions: paste either format, get the other back.

### Does it handle dates before 1970 or far in the future?

Yes. Negative epoch values are moments before the epoch: `-86400` is 1969-12-31. JavaScript's `Date` covers roughly plus or minus 275,000 years, which handles every realistic use. For arbitrary-precision dates (astronomy, history) use a dedicated library.

### Is the live clock draining my battery?

No. It's a single one-second `setInterval`, the same cost as the clock in your OS menu bar, and it only runs while the page is open.