date-time-tools
Batch Timestamp Converter
Paste multiline Unix timestamps and convert each row to ISO, local time, UTC, Unix seconds, or Unix milliseconds with a reviewable seconds/milliseconds unit column.
Tool workspace
The interactive tool requires JavaScript.
Instructions
Choose auto-detect or force the unit. If your source system documents the unit, prefer the forced option.
Select ISO, local time, UTC, Unix seconds, or Unix milliseconds output, then review the detected-unit column before copying.
Use this browser-local converter for log exports, spreadsheet columns, event data, and API response fields. The result keeps the detected seconds/milliseconds unit visible for review.
Direct answer
For batch Unix timestamp conversion, enter one integer per line, choose auto-detect or force seconds/milliseconds, and select the output format. Auto mode treats 10 digits or fewer as seconds and 11 digits or more as milliseconds after removing a leading minus sign.
How to use this tool
- Paste one Unix timestamp per line. A batch may include 10-digit seconds and 13-digit milliseconds.
- Choose auto-detect or force the unit. If your source system documents the unit, prefer the forced option.
- Select ISO, local time, UTC, Unix seconds, or Unix milliseconds output, then review the detected-unit column before copying.
How auto-detection works
The tool checks each integer by digit length: after removing a leading minus sign, 10 digits or fewer are seconds and 11 digits or more are milliseconds. The rule is visible but does not replace source-system documentation.
Useful batch scenarios
Use it for log review, event data checks, spreadsheet imports, API response cleanup, and converting timestamp columns into readable time. The copied output is tab-separated for spreadsheet review.
Conversion limits
The tool only formats timestamps locally in the browser. It does not read external timezone APIs, log platforms, databases, audit systems, or business rules.
Frequently asked questions
Does the tool upload my timestamps?
No. Batch conversion runs locally in the browser without accounts, databases, backend services, or external APIs.
Why show the detected unit?
Seconds and milliseconds mistakes can shift an entire batch. Keeping seconds or milliseconds visible makes review easier.
How are blank and invalid rows handled?
Blank lines are ignored. Non-integers, unsafe integers, and unconvertible values appear as ERROR rows in the output.
Can I use this directly for audit or transaction records?
Treat it as a cleanup and review helper. Formal records should be checked against the source system, timezone assumptions, and business rules.
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