Are Unix timestamps affected by daylight saving time (DST) or timezones?

No. Unix time is an invariant metric based strictly on UTC. Two people on opposite sides of the planet reading their clocks at the exact same moment share the identical Unix timestamp.

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

For current dates, 10-digit numbers (starting with 17...) represent seconds, while 13-digit numbers (starting with 17...) represent milliseconds.

Is the Year 2038 Problem solved?

Yes, on modern 64-bit systems. A 64-bit timestamp will remain safe from integer overflow for roughly 292 billion years.

Can Unix timestamps be negative?

Yes. Dates before January 1, 1970, UTC are represented by negative numbers. For example, -86400 corresponds to December 31, 1969, 00:00:00 UTC.

Is any conversion data transmitted to external servers?

No. All timestamp conversions occur locally on your machine via JavaScript date functions in your browser.

Unix Timestamp Converter

Try the free Unix Timestamp Converter tool in the Date/Time category provided by WebToolBox right in your browser. Process your tasks quickly and securely without any installation.

Unix -> ISO

What is a Unix Timestamp (POSIX Epoch Time)?

A Unix timestamp (also known as Epoch time or POSIX time) is an integer representing the total elapsed seconds (or milliseconds) since midnight on January 1, 1970, UTC (Coordinated Universal Time), known as the Unix Epoch.

Because it is an absolute numerical value completely independent of geographic timezones or daylight saving changes, it serves as the universal clock standard across database schemas, logging infrastructures, API tokens (such as JWT 'exp' claims), and distributed cloud services.

Standard timestamps are 10-digit integers measuring seconds, while web technologies like JavaScript and modern telemetry platforms commonly use 13-digit integers measuring milliseconds.

입출력 예시 (Examples)

입력 (Input)	결과 (Output)	설명
0	1970-01-01 00:00:00 UTC	The beginning of the Unix Epoch
1700000000	2023-11-14 22:13:20 UTC	10-digit standard seconds timestamp
1700000000000	2023-11-14 22:13:20.000 UTC	13-digit millisecond timestamp

Timestamp Resolution Units & Usage Comparison

Unit of Time	Digit Length	Format Example	Common Technologies & Frameworks
Seconds	10 digits	1700000000	Linux system time, Python time.time(), JWT exp claim, Redis TTL
Milliseconds	13 digits	1700000000000	JavaScript Date.now(), Java System.currentTimeMillis()
Microseconds	16 digits	1700000000000000	PostgreSQL high-resolution timestamps, distributed tracing
Nanoseconds	19 digits	1700000000000000000	Go time.Now().UnixNano(), high-frequency algorithmic trading

How to Use the Online Unix Timestamp Converter

Enter a 10-digit (seconds) or 13-digit (milliseconds) timestamp into the input field.
Or switch modes to pick a human date using the integrated calendar and time picker.
The tool immediately displays the converted Coordinated Universal Time (UTC) and local timezone representations.
Click the 'Current Timestamp' button to grab the exact real-time timestamp instantly.

Developer Best Practices & Implementation Tips

Seconds vs. Milliseconds Pitfall: Passing a 10-digit seconds timestamp into JavaScript's `new Date(ts)` results in January 1970 because JS expects milliseconds. Always multiply by 1,000 first.
The Year 2038 Problem (Y2K38): 32-bit signed integers will overflow on January 19, 2038 at 03:14:07 UTC. Always specify 64-bit integers (BIGINT) in your database schemas.
Store in UTC, Render in Local: Always persist timestamps in UTC within databases and APIs; only format into local timezones at the presentation layer.

프로그래밍 언어별 사용 예제 (Code Examples)

JavaScript / Node.jsjavascript

// Get current timestamps
const nowSec = Math.floor(Date.now() / 1000); // 10 digits
const nowMs = Date.now(); // 13 digits

// Convert timestamp to human date
const dateObj = new Date(nowSec * 1000);
console.log(dateObj.toISOString()); // 2023-11-14T22:13:20.000Z

Python 3python

import time
from datetime import datetime, timezone

# Current timestamp
epoch_seconds = int(time.time())

# Convert to UTC ISO string
dt = datetime.fromtimestamp(epoch_seconds, tz=timezone.utc)
print(dt.isoformat())

FAQ (자주 묻는 질문)

Are Unix timestamps affected by daylight saving time (DST) or timezones?: No. Unix time is an invariant metric based strictly on UTC. Two people on opposite sides of the planet reading their clocks at the exact same moment share the identical Unix timestamp.
How can I tell whether a timestamp is in seconds or milliseconds?: For current dates, 10-digit numbers (starting with 17...) represent seconds, while 13-digit numbers (starting with 17...) represent milliseconds.
Is the Year 2038 Problem solved?: Yes, on modern 64-bit systems. A 64-bit timestamp will remain safe from integer overflow for roughly 292 billion years.
Can Unix timestamps be negative?: Yes. Dates before January 1, 1970, UTC are represented by negative numbers. For example, -86400 corresponds to December 31, 1969, 00:00:00 UTC.
Is any conversion data transmitted to external servers?: No. All timestamp conversions occur locally on your machine via JavaScript date functions in your browser.

Date/Time — Tool Navigation

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