Days Since Unix Epoch Calculator
Count the whole days from the Unix epoch (January 1, 1970) to any date — the epoch day number, plus weeks and years elapsed.
How it works
days since epoch = the date − 1970-01-01, counted in whole UTC days · this is the Unix timestamp in seconds ÷ 86,400 · weeks = days ÷ 7 · years ≈ days ÷ 365.2425
The Unix epoch is midnight UTC on January 1, 1970 — the zero point most computers count time from. The "epoch day" is the number of whole days since then, which equals the Unix timestamp in seconds divided by 86,400 and is used in date libraries and databases as a compact day index. Dates before 1970 give a negative count. Because it counts whole UTC days it is unaffected by time zones or daylight saving.
Worked example
From January 1, 1970 to September 15, 2026 is 20,711 days — about 56.70 years, or 2,958 whole weeks and 5 days.
Sources: Unix time — Wikipedia
Frequently asked questions
How does this relate to a Unix timestamp?
A Unix timestamp counts seconds since the epoch; divide it by 86,400 (seconds in a day) and take the whole part to get the epoch day number this tool reports. Multiply the days by 86,400 to get the timestamp at midnight UTC.
Why January 1, 1970?
It was chosen as a convenient recent round date when Unix time was designed in the early 1970s. It has been the standard reference point for computer clocks ever since.
What about dates before 1970?
They are counted as negative — the number of days before the epoch. Some older 32-bit systems could not represent dates before 1970 or beyond January 2038, but the day count itself is simply negative.
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This calculator is for educational purposes. Double-check important results before acting on them.