How to use this tool
- Pick seconds or milliseconds, matching what you're converting.
- Enter a timestamp on the left to see it as a local, UTC, and ISO 8601 date — or use "Use now" to grab the current time.
- Enter a date on the right to convert it back into a timestamp, then copy it.
Common mistakes to avoid
- Mixing up seconds and milliseconds is the most common mistake — check the digit count against the unit toggle before trusting the result.
Why convert timestamps in the browser?
This uses JavaScript's native Date object, the same one every browser and Node.js environment uses internally — so the conversion is exactly what your code would produce, with no server round trip needed for something this fast.
Frequently asked questions
- How do I know if a timestamp is in seconds or milliseconds?
- A 10-digit number (like 1735689600) is Unix seconds; a 13-digit number (like 1735689600000) is milliseconds — JavaScript's Date.now() uses milliseconds, while many APIs and databases use seconds.
- What timezone is "Local" shown in?
- Your device's current timezone setting, as reported by the browser. The UTC and ISO 8601 rows are timezone-independent, so use those when sharing a timestamp with someone in a different timezone.
- Does this account for daylight saving time?
- Yes — the conversion uses your browser's own timezone database, which handles DST transitions correctly for your current location.
How GetByteRush compares
Most free tools for this online work the same way: you upload your file to their server, wait, then download the result — which means your file (and often your email, for a "free" account) sits on someone else's infrastructure. Here's the actual difference:
| Feature | GetByteRush | Typical online timestamp converters |
|---|---|---|
| Seconds vs. milliseconds | Explicit toggle, both supported | Sometimes ambiguous or seconds-only |
| UTC and ISO 8601 shown | Always, alongside local time | Varies |
| Account required | Never | Rarely, but happens |
("Typical online tools" reflects publicly documented behavior of common free file-processing sites as of 2026 — always check a specific competitor's own privacy policy and pricing page, since these details change.)