Convert Unix seconds to a UTC date or an ISO date to seconds. Compare timestamps without mixing seconds, milliseconds, and local time.
How to use
Select the direction. Enter seconds for timestamp input, or an ISO date with a timezone for date input. Check the UTC result before using it.
Example
0 converts to 1970-01-01T00:00:00.000Z. A millisecond timestamp must be divided by 1,000 before entering it as seconds.
FAQ
Why does the hour differ from my clock?
UTC and local time can differ. Include Z or an explicit timezone offset when converting an ISO date.
Related tools
A practical task
Document the unit next to a copied timestamp. A modern millisecond value entered as seconds can produce an implausible date far in the future. Check one known event from the source system before converting a whole series.
Another useful question
Can I enter a date without a timezone?
The date input requires a timezone so the instant is unambiguous. Add Z for UTC only when the source date actually represents UTC.
Settings and formats
| Field | Values |
|---|---|
| Operation | Seconds to date (timestamp); Date to seconds (date) |
Details for interpreting the result
| Detail | Explanation |
|---|---|
| UTC timestamps | UTC is a shared time reference. An ISO timestamp ending in Z uses UTC; a numeric offset states a difference from it. A local clock reading without an offset is ambiguous when exchanging timestamps. |
| Seconds and milliseconds | Unix time is commonly exchanged in seconds or milliseconds. A value in the wrong unit can yield a date far from the intended one. Confirm the unit in the source system rather than guessing from a label. |
| Calendar dates and timezones | A calendar date has no clock time on its own. Timezone conversion can move an instant to a different local day. Decide if the task needs a date label or a moment in time before changing formats. |
| Numeric precision | JavaScript numbers cannot represent every large integer exactly. Long account numbers, order identifiers, and arbitrary precision decimals should remain strings or use a suitable numeric library in the receiving application. |
| Units and quantities | Arithmetic needs compatible quantities. A count, a currency amount, a rate, and a label can share the same digits but mean different things. Keep units next to the inputs when checking a numerical result. |
| Strings and values | The JSON string "12" differs from the number 12, and "false" differs from false. Type changes affect comparisons and imports. Keep identifiers as strings when their leading zeros or exact digits matter. |
| Similar looking text | Two strings can look identical but use different Unicode sequences. An accented letter can be stored directly or as a letter plus an accent. Visual similarity alone does not establish byte equality. |