How do I convert milliseconds to a readable date in Python?

datetime.fromtimestamp(ms / 1000) — divide by 1000 first since Python's fromtimestamp expects seconds, not milliseconds.

Milliseconds to Seconds Converter

Q: How do I convert milliseconds to a readable date in different languages?

JavaScript: new Date(ms).toISOString() — pass ms directly. Python: datetime.fromtimestamp(ms / 1000) — divide by 1000 first since Python expects seconds. Go: time.UnixMilli(ms) (Go 1.17+) or time.Unix(ms/1000, (ms%1000)*int64(time.Millisecond)) . Java: Instant.ofEpochMilli(ms) . SQL (PostgreSQL): to_timestamp(ms / 1000.0) .

Convert milliseconds to seconds instantly. Paste a 13-digit JavaScript timestamp or any millisecond value to get seconds, a human-readable date, and the equivalent Unix timestamp.

Convert Milliseconds to Seconds

Enter any value in milliseconds — a Date.now() output, a 13-digit API timestamp, or a duration — to convert it to seconds and a readable date/time.

ms → seconds: Divide by 1000 — instantly shown with decimal precision
ms → readable date: Decode a 13-digit epoch timestamp to UTC and local time
Duration conversion: Convert millisecond durations to minutes, hours, and days
Reverse: Convert seconds timestamps to milliseconds for JavaScript use

Convert Milliseconds →

Milliseconds Conversion Reference

1 second = 1,000 milliseconds
1 minute = 60,000 milliseconds
1 hour = 3,600,000 milliseconds
1 day = 86,400,000 milliseconds
1 week = 604,800,000 milliseconds
30 days = 2,592,000,000 milliseconds
1 year (365 days) = 31,536,000,000 milliseconds

When You Encounter Millisecond Values

JavaScript Date.now(): Always returns milliseconds — a 13-digit number. Divide by 1000 before storing as a Unix timestamp or passing to server-side systems that expect seconds
API responses: Many modern REST APIs return created_at or timestamp fields in milliseconds — check whether the value is 10 or 13 digits to identify the unit
Performance timing: performance.now() in browsers returns milliseconds with sub-millisecond decimal precision — useful for measuring function execution time
Log timestamps: Java's System.currentTimeMillis() and many logging frameworks output millisecond timestamps — convert to seconds for Unix tools like date -d @timestamp

Frequently Asked Questions

How do I convert milliseconds to a readable date in different languages?

JavaScript: new Date(ms).toISOString() — pass ms directly. Python: datetime.fromtimestamp(ms / 1000) — divide by 1000 first since Python expects seconds. Go: time.UnixMilli(ms) (Go 1.17+) or time.Unix(ms/1000, (ms%1000)*int64(time.Millisecond)). Java: Instant.ofEpochMilli(ms). SQL (PostgreSQL): to_timestamp(ms / 1000.0).

How can I tell if a timestamp is in seconds or milliseconds?

Count the digits: a 10-digit number (e.g., 1700000000) is a Unix second timestamp representing a date in the 2000s. A 13-digit number (e.g., 1700000000000) is a millisecond timestamp. As a rule: if the value divided by 1000 gives a plausible recent year when decoded as a Unix timestamp, the original was in milliseconds. Values in the billions that decode to dates in 1970–2001 are likely second timestamps that were misread as milliseconds.

Why do some systems use milliseconds and others use seconds?

The difference comes from historical convention and precision requirements. Unix (1970s) standardized on seconds — sufficient for file timestamps and scheduling. JavaScript (1995) chose milliseconds to support sub-second UI animations. Java followed JavaScript's convention. Modern systems often use milliseconds or even microseconds/nanoseconds for distributed systems (where ordering events within a second matters). The lack of a single universal standard is why timestamp unit confusion is so common.