Unix timestamps: seconds or milliseconds?
Check units and time zones when a timestamp shows 1970 or an unexpected time.
Open the Unix time converterCheck the source unit first
Unix timestamps count time from 1970-01-01 00:00:00 UTC. Milliseconds are 1000 times seconds. For recent dates, 10 digits often mean seconds and 13 mean milliseconds. These are clues, not proof: check the API or log specification.
Two inputs, one instant
1704067200 seconds and 1704067200000 milliseconds both represent 2024-01-01 00:00:00 UTC. Select Asia/Tokyo to display 2024-01-01 09:00:00. Do not add nine hours to the input just to change the displayed time zone.
Automatic detection and older dates
This tool treats an absolute value of at least one trillion, or exactly 13 digits without a sign, as milliseconds; other values are seconds. Older millisecond timestamps can be misclassified. If the source specifies milliseconds, divide by 1000 and enter seconds: 946684800000 milliseconds becomes 946684800 seconds, or 2000-01-01 00:00:00 UTC.
Unexpected 1970 dates or invalid input
Reading a seconds value as milliseconds in another system can produce a date near 1970. Zero means the epoch; -1 second means 1969-12-31 23:59:59 UTC. Blank input, text, Infinity and dates outside the representable range are rejected. Enter 0 explicitly instead of leaving the field empty.
Fractions and time zones
1.5 seconds gives 00:00:01.500 UTC. The displayed Epoch (sec) is an integer rounded down, including for negative values. Daylight saving transitions can repeat or skip local times. For important log comparisons, check UTC and the original offset as well.
Data handling
Conversions run in your browser. Up to 20 history entries are kept in its local storage. Use the tool’s clear-history button on a shared device. This guide has no input fields.