Seconds or milliseconds — how can I tell?

Unix timestamps today are 10 digits in seconds and 13 digits in milliseconds. The converter auto-detects based on length.

Why does my date look off by a day?

Almost always a timezone issue. Confirm you are comparing the same timezone on both sides of the conversion.

Unix time ignores leap seconds by definition. Human-readable dates from this tool reflect civil time, not astronomical UTC.

Converters

Convert between Unix timestamps (seconds or milliseconds), ISO 8601, and human-readable dates. Everything runs in your browser.

Timestamp or Date String

Accepts Unix seconds, Unix milliseconds, ISO 8601, or any Date.parse()-compatible string

Timezone

Enter a timestamp or date string above to convert it

How to convert timestamps

Convert between Unix timestamps, ISO 8601 strings, and human-readable dates across any timezone.

Paste a timestamp or date
Drop in a Unix seconds or milliseconds value, or an ISO 8601 date string.
Choose the target format
Pick seconds, milliseconds, ISO 8601, or a human-readable date/time.
Switch timezone
View the result in UTC, your local timezone, or any named IANA timezone.
Copy the conversion
Copy the converted value for use in code, logs, or a support ticket.

? Seconds or milliseconds — how can I tell?: Unix timestamps today are 10 digits in seconds and 13 digits in milliseconds. The converter auto-detects based on length.
? Why does my date look off by a day?: Almost always a timezone issue. Confirm you are comparing the same timezone on both sides of the conversion.
? Does it handle leap seconds?: Unix time ignores leap seconds by definition. Human-readable dates from this tool reflect civil time, not astronomical UTC.