Web and Digital
Unix Timestamp Calculator
Unix Timestamp Calculator convert a UTC date and time to Unix epoch seconds and milliseconds or convert an epoch value back to ISO UTC.
Web and Digital
Unix Timestamp Calculator
Convert a UTC date and time to Unix epoch seconds and milliseconds or convert an epoch value back to ISO UTC.
Formula
Unix timestamp = elapsed UTC milliseconds since 1970-01-01T00:00:00Z, divided by 1,000 for seconds.
About the Unix Timestamp Calculator
Convert a UTC date and time to Unix epoch seconds and milliseconds or convert an epoch value back to ISO UTC.
How the Unix Timestamp Calculator Works
Date input is interpreted explicitly as UTC; epoch input is normalized from the selected seconds or milliseconds unit before ISO formatting.
Formula
Unix timestamp = elapsed UTC milliseconds since 1970-01-01T00:00:00Z, divided by 1,000 for seconds.
The calculation runs in your browser. Values are validated for required ranges, compatible units, and method-specific restrictions before results are displayed.
Required Inputs
- Conversion direction (required).
- UTC date and time (optional).
- Epoch value (optional).
- Epoch input unit (required).
Results Reported
The result panel reports the final answer and the intermediate quantities needed to check the calculation:
- Unix epoch seconds
- Unix epoch milliseconds
- ISO 8601 UTC date and time
- UTC calendar date
- UTC clock time
Unix Timestamp Calculator Example
Select Example Data in the calculator to load this reproducible input set:
| Input | Example value |
|---|---|
| Conversion direction | date_to_epoch |
| UTC date and time | 2026-07-13T12:00:00 |
| Epoch value | 1783944000 |
| Epoch input unit | seconds |
How to Use the Calculator
- Confirm that the calculator title and formula match the quantity you need.
- Enter every required value using the unit shown with its field.
- Select Example Data to inspect a valid input set, or enter your own values and select Calculate.
- Review all reported values and the displayed formula before using the answer.
- Use Copy Result or Download CSV when you need a reusable record.
Accuracy and Limitations
Unix timestamps represent instants without a time zone. Leap seconds are not represented by ordinary JavaScript Date, and very large dates may exceed supported range.
Keep units consistent, use measurements that represent the actual situation, retain full precision during the calculation, and round only the final answer. Professional decisions may require current official rules, field measurements, laboratory methods, or specialist review.
Frequently Asked Questions
What does the Unix Timestamp Calculator calculate?
Convert a UTC date and time to Unix epoch seconds and milliseconds or convert an epoch value back to ISO UTC.
Which formula does the Unix Timestamp Calculator use?
Unix timestamp = elapsed UTC milliseconds since 1970-01-01T00:00:00Z, divided by 1,000 for seconds. Date input is interpreted explicitly as UTC; epoch input is normalized from the selected seconds or milliseconds unit before ISO formatting.
What should I check before using the Unix Timestamp Calculator result?
Unix timestamps represent instants without a time zone. Leap seconds are not represented by ordinary JavaScript Date, and very large dates may exceed supported range.