Use the free Batch Timestamp Converter below: your data never leaves your browser — all work happens on your device, and nothing is uploaded to any server.
Computers count time in seconds or milliseconds since 1 January 1970, a number called an epoch timestamp. Humans read dates like 2024-03-04. Logs, databases, and APIs speak the first language, and people speak the second, so converting between them is constant work. The Batch Timestamp Converter converts a pasted list of epoch values, one per line, into readable dates all at once. It only does batch lists: a single timestamp belongs in a single-value converter, while this tool exists for the long lists that real logs and exports produce.
The input unit is the first thing to get right. Some systems count seconds, and some count milliseconds, and the two differ by a factor of a thousand. A seconds value like 1709558400 means March 2024, but read as milliseconds it means a date in January 1970, which is obviously wrong. The auto mode handles this by size: values above one trillion are treated as milliseconds, and smaller values as seconds. That rule works for all realistic dates from the 1970s onward. When you know the unit for certain, pick seconds or milliseconds directly and remove all doubt.
To use it, paste your epoch values one per line into the box. The sample mixes seconds values, a zero, and a milliseconds value, which is a realistic mixed export. Choose the input unit, choose the output format, and press Convert all timestamps. The converted dates appear below with counts of converted and skipped lines, and the download button saves the list as a text file.
Output formats follow the same advice as other date tools. YYYY-MM-DD is best for sorting and importing. The long forms fit reports people will read. The timestamp form with hours, minutes, and seconds fits log analysis, where the time of day matters as much as the date. The epoch form as output is pointless for this tool, since the input already is epoch, but it is offered for consistency with the shared format list.
Time zones deserve a plain explanation, because they cause the most confusion in timestamp work. Epoch values describe an absolute instant, but a readable date depends on where you stand. The same timestamp is 4 March in London and still 3 March in New York. This tool shows dates in your browser’s time zone, which is the right choice for personal log reading and the wrong choice for comparing logs across time zones. When a team spans time zones, agree on one zone, usually UTC, and convert with that zone in mind before comparing.
Skipped lines are counted, never silently changed. A line with letters, a blank line, or a value so large that it overflows a date is left out of the output. If a whole column comes back skipped, the values are probably not epoch at all: they may be formatted dates, durations, or IDs that merely look numeric. Check a few source values before converting the whole list.
People use this tool to read timestamp columns from database exports, to turn API log output into a timeline, and to prepare epoch data for charts and reports. Because the work happens in the browser, lists that come from private systems never leave the device, and closing the page clears the paste from view.
How to convert many timestamps at once
- Paste your epoch values, one per line, into the box.
- Choose the input unit, or leave it on auto.
- Choose the output format for your readable dates.
- Press Convert all timestamps and check the converted and skipped counts.
- Press Download list to save the converted dates.
Frequently asked questions
How does auto mode tell seconds from milliseconds? Values above one trillion are treated as milliseconds, smaller values as seconds. That rule fits all realistic dates.
Why is my date one day off? Time zones. The tool shows your browser’s zone, so the same instant can fall on different dates in different zones.
What does epoch zero mean? Zero means 1 January 1970, the starting point of epoch time. It is a valid value, not an error.
Is my data uploaded? No. Everything runs in your browser, and nothing is sent or stored.
Paste the numbers, read the dates, and check the zone before you compare across teams. That is the whole discipline of timestamp work in one tool.
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