Quick start
- Use Date to timestamp mode when you have a UTC date and time.
- Use Timestamp to date mode when you have Unix seconds or milliseconds.
- Choose the correct unit before converting a timestamp.
Best uses
These are the situations this tool is meant for. If your task is close to one of these, the examples and notes below can help you choose the right inputs.
- Convert a UTC date and time into Unix seconds for logs or APIs.
- Convert Unix seconds or milliseconds into an ISO UTC timestamp.
- Check whether a timestamp is seconds or milliseconds.
- Compare date-time values without local time-zone ambiguity.
What this calculator is solving
The Unix Timestamp Converter is for log, API, database, and developer work where time is stored as a count from the Unix epoch. It uses UTC so the conversion does not silently depend on the viewer’s local time zone.
You do not need to memorize the formula first. Start by matching each input label on the calculator to the number, date, unit, or setting you actually have.
The formula in plain language
In plain language: Date mode counts seconds and milliseconds since 1970-01-01T00:00:00Z. Timestamp mode reverses that count back to UTC date and time. The examples on the page are there so you can compare your inputs with a filled-out calculation before copying the answer.
If that sounds abstract, use the example cards on the calculator page. They show a complete set of inputs and the kind of answer you should expect.
How to read the answer
Read the headline result first. Then look at the smaller supporting lines because they explain the parts behind the answer, such as totals, units, ranges, or formula steps.
- Unix seconds is the common compact timestamp form.
- Milliseconds is often used in JavaScript and browser APIs.
- UTC ISO output shows the converted instant in a readable standard format.
Common mistakes to avoid
If the answer looks strange, the most likely cause is a small input mismatch: the wrong unit, date, weight, scale, mode, or policy assumption.
- Do not mix seconds and milliseconds; millisecond timestamps are 1,000 times larger.
- Do not enter local time unless you have already converted it to UTC.
- Check application-specific time-zone rules before scheduling real events.
Research and references
These references shaped the calculator assumptions, unit choices, or safety notes.
Examples from the calculator
Unix seconds
UTC ISO date-time
1970-01-01T00:00:00Z
FAQ in plain language
When should I use the Unix Timestamp Converter?
Use it when your task matches one of these common needs: Convert a UTC date and time into Unix seconds for logs or APIs. Convert Unix seconds or milliseconds into an ISO UTC timestamp. It works best when you already know the values, dates, units, or settings the page asks for.
What is the Unix Timestamp Converter doing with my inputs?
In plain language: Date mode counts seconds and milliseconds since 1970-01-01T00:00:00Z. Timestamp mode reverses that count back to UTC date and time. The examples on the page are there so you can compare your inputs with a filled-out calculation before copying the answer.
What should I double-check before trusting the answer?
The converter uses UTC on purpose. Local time zones, daylight saving time, and application storage rules can change how a timestamp appears elsewhere. Also check that you used the right unit, date, scale, or mode because small input changes can change the result.
Related tools
- Time Zone Calculator Convert a UTC date and time into a selected IANA time zone.
- Date Calculator Find days between dates or add and subtract years, months, weeks, and days.
- Day of the Week Calculator Find the weekday name and ISO weekday number for a calendar date.
Privacy and copying results
Recent answers stay visible only while you work in the current browser tab. They are not sent to a server.
Use Copy answer when you want to paste the expression and result into notes, homework, a message, or another document. Check the units and assumptions before copying.