Date & Time Tools
Bulk Unix Timestamp Converter
Paste a column of Unix timestamps (seconds or milliseconds) and convert every row to a date in any time zone. Mixed lists, custom formats, CSV and JSON output.
Bulk Unix timestamp converter
Number unit
Auto treats values at or above 1,000,000,000,000 as milliseconds and everything else as seconds.
Output format
1970-01-01T00:00:00.000Z
Time zone
Paste any column of epoch numbers, or mix in ISO date strings. Conversion runs in your browser. Nothing is uploaded.
Row by row
First 8 of 8 rows
| # | Input | Unit | Output |
|---|---|---|---|
| 1 | 1700000000 | s | 2023-11-14T22:13:20.000Z |
| 2 | 1735689600 | s | 2025-01-01T00:00:00.000Z |
| 3 | 1577836800000 | ms | 2020-01-01T00:00:00.000Z |
| 4 | 0 | s | 1970-01-01T00:00:00.000Z |
| 5 | 1893456000 | s | 2030-01-01T00:00:00.000Z |
| 6 | 2026-01-15T08:30:00Z | iso | 2026-01-15T08:30:00.000Z |
| 7 | not a real timestamp | error | not a Unix timestamp or recognizable date |
| 8 | 1750000000.5 | s | 2025-06-15T15:06:40.500Z |
What this tool accepts
- 1700000000 is read as Unix seconds.
- 1700000000000 is read as Unix milliseconds.
- 1700000000.5 is accepted as a fractional second.
- 2026-01-15T08:30:00Z and other ISO 8601 strings are reformatted.
- Blank lines are skipped, unless "Keep blank rows" is on.
- Unrecognized rows stay in place with an inline error.
Common bulk timestamp sources
- created columns in Stripe exports use seconds.
- MongoDB _id first four bytes encode seconds.
- Posthog and Mixpanel event exports often use milliseconds.
- S3 access logs and CloudFront logs use seconds in their time field.
- Twitter and X archive JSON files mix seconds and ISO 8601 strings.
How to use
- Paste a column of Unix timestamps, one per line. Mixing seconds and milliseconds is fine, and ISO 8601 strings like 2026-01-15T08:30:00Z are also accepted.
- Pick the number unit. Auto detects seconds vs milliseconds per row; switch to Seconds or Milliseconds to force one interpretation.
- Choose the output format and the time zone. Use ISO 8601 UTC for technical pipelines, EU or US calendar for reports, or a custom token format like YYYY-MM-DD HH:mm:ss for a custom column.
- Pick the output shape: one value per line, a two-column CSV with input and output, or a JSON array.
- Read the row by row table to see which rows were parsed as seconds, milliseconds, or ISO strings, and which rows failed. Use Copy or Download to save the result.
About this tool
Bulk Unix Timestamp Converter takes a column of Unix epoch numbers (or a mixed list of epoch numbers and ISO 8601 date strings) and converts every row at once. Each row is auto-detected as seconds, milliseconds, or an ISO date string, so a real CSV export from Stripe, Posthog, Mixpanel, S3 access logs, or a MongoDB collection can be pasted directly. Output respects the time zone you pick (UTC, your browser local time, or any IANA zone the browser exposes through Intl.supportedValuesOf), and you can choose between ISO 8601 UTC, ISO 8601 with offset, RFC 2822, US calendar, EU calendar, weekday plus date, date only, time only, a relative description ("3 hours ago"), or a custom token format using YYYY, MM, DD, HH, mm, ss, A, Z and the rest. The output column can be copied as plain text, as a two-column CSV with the original input and the formatted value side by side, or as a JSON array of input and output objects. Invalid rows do not abort the conversion: they stay in place with a clear inline error and the row by row table shows exactly which unit each row was treated as. Useful for cleaning analytics exports, reading log files in your time zone, preparing data for a spreadsheet, sharing a list of events with the right format for a report, or any time you have more than one epoch number to convert. Everything runs locally in your browser. The list you paste is never uploaded.
Free to use. Works in your browser. No signup, no login.
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