Timestamp Converter

About this timestamp converter

Distributed systems, JWT expirations, log aggregators, and browser devtools all speak different time dialects: Unix seconds, Unix milliseconds, RFC 1123 strings, and ISO 8601 with offsets. This page normalizes a single input into the representations engineers most often copy into tickets or unit tests.

Numeric detection is length-based: ten or fewer digits are treated as seconds; longer digit runs are treated as milliseconds. You can also paste human-readable strings that Date.parse understands, such as ISO timestamps with a Z suffix.

Typical workflows

• Converting Grafana log timestamps into ISO for SQL queries.
• Double-checking JWT exp claims before they hit production.
• Explaining to support how a UTC instant maps to a customer’s local wall clock.

How to use this page

1. Paste a numeric timestamp or a parseable date string into the editor.
2. Click Convert to populate the result list.
3. Use the per-row Copy buttons to grab the exact format your downstream tool expects.

Timezone caveats

ISO output is always UTC (Z). Local string output depends on the machine running the browser, so remote teammates may see different local strings for the same instant.

Frequently asked questions

Why does my 10-digit number look wrong?

Confirm it is seconds, not milliseconds truncated. Millisecond values are usually 13 digits.

Does this handle leap seconds?

JavaScript dates follow ECMAScript rules; extremely edge-case leap-second smearing may differ from astronomy libraries.

Is input sent to a backend?

No. Conversion uses your browser’s Date implementation only.

Why did parsing fail?

Ambiguous locale-specific strings may not parse. Prefer ISO 8601 forms for reliable results.