Timestamp Format Cheatsheet: Quick Reference Guide

Overview

This comprehensive cheatsheet provides quick reference for all common timestamp formats used in programming and data exchange. All examples use January 1, 2024, 12:00:00 UTC as the reference time.

Quick Reference Table

Unix Timestamp Formats

Seconds (10 digits)

Format: Integer representing seconds since January 1, 1970, 00:00:00 UTC

1704110400

When to Use:

• Legacy systems and APIs
• Storage efficiency (4 bytes as int32)
• Year 2038 problem considerations

Code Examples:

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JAVASCRIPT
1// JavaScript
2const timestamp = Math.floor(Date.now() / 1000);
3// 1704110400
4
5const date = new Date(timestamp * 1000);
6// 2024-01-01T12:00:00.000Z

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PYTHON
1# Python
2import time
3timestamp = int(time.time())
4# 1704110400
5
6from datetime import datetime
7date = datetime.fromtimestamp(timestamp)
8# 2024-01-01 12:00:00

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PHP
1// PHP
2$timestamp = time();
3// 1704110400
4
5$date = date('Y-m-d H:i:s', $timestamp);
6// 2024-01-01 12:00:00

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GO
1// Go
2import "time"
3
4timestamp := time.Now().Unix()
5// 1704110400
6
7date := time.Unix(timestamp, 0)
8// 2024-01-01 12:00:00 +0000 UTC

Milliseconds (13 digits)

Format: Integer representing milliseconds since Unix epoch

1704110400000

When to Use:

• JavaScript applications (default for Date.now())
• Modern web APIs
• Millisecond precision needed

Code Examples:

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JAVASCRIPT
1// JavaScript
2const timestamp = Date.now();
3// 1704110400000
4
5const date = new Date(timestamp);
6// 2024-01-01T12:00:00.000Z

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PYTHON
1# Python
2import time
3timestamp = int(time.time() * 1000)
4# 1704110400000
5
6from datetime import datetime
7date = datetime.fromtimestamp(timestamp / 1000)

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JAVA
1// Java
2long timestamp = System.currentTimeMillis();
3// 1704110400000
4
5Date date = new Date(timestamp);
6// Mon Jan 01 12:00:00 UTC 2024

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CSHARP
1// C#
2long timestamp = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds();
3// 1704110400000
4
5DateTimeOffset date = DateTimeOffset.FromUnixTimeMilliseconds(timestamp);

Microseconds (16 digits)

Format: Integer representing microseconds since Unix epoch

1704110400000000

When to Use:

• High-precision logging and monitoring
• Performance benchmarking
• Scientific applications

Code Examples:

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PYTHON
1# Python
2import time
3timestamp = int(time.time() * 1_000_000)
4# 1704110400000000
5
6date = datetime.fromtimestamp(timestamp / 1_000_000)

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GO
1// Go
2timestamp := time.Now().UnixMicro()
3// 1704110400000000
4
5date := time.UnixMicro(timestamp)

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RUST
1// Rust
2use std::time::{SystemTime, UNIX_EPOCH};
3
4let timestamp = SystemTime::now()
5    .duration_since(UNIX_EPOCH)
6    .unwrap()
7    .as_micros();
8// 1704110400000000

Nanoseconds (19 digits)

Format: Integer representing nanoseconds since Unix epoch

1704110400000000000

When to Use:

• Ultra-precise timing requirements
• Performance profiling
• Trading systems

Code Examples:

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GO
1// Go
2timestamp := time.Now().UnixNano()
3// 1704110400000000000
4
5date := time.Unix(0, timestamp)

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RUST
1// Rust
2let timestamp = SystemTime::now()
3    .duration_since(UNIX_EPOCH)
4    .unwrap()
5    .as_nanos();
6// 1704110400000000000

ISO 8601 Formats

Basic Format (UTC)

Format: YYYY-MM-DDTHH:MM:SSZ

2024-01-01T12:00:00Z

When to Use:

• International data exchange
• RESTful APIs
• JSON data storage

Code Examples:

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JAVASCRIPT
1// JavaScript
2const isoString = new Date().toISOString();
3// 2024-01-01T12:00:00.000Z

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PYTHON
1# Python
2from datetime import datetime, timezone
3iso_string = datetime.now(timezone.utc).isoformat().replace('+00:00', 'Z')
4# 2024-01-01T12:00:00Z

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PHP
1// PHP
2$iso_string = gmdate('Y-m-d\TH:i:s\Z');
3// 2024-01-01T12:00:00Z

Extended Format (with milliseconds)

Format: YYYY-MM-DDTHH:MM:SS.sssZ

2024-01-01T12:00:00.000Z

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JAVASCRIPT
1// JavaScript (default)
2new Date().toISOString();
3// 2024-01-01T12:00:00.000Z

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PYTHON
1# Python
2datetime.now(timezone.utc).isoformat(timespec='milliseconds').replace('+00:00', 'Z')
3# 2024-01-01T12:00:00.000Z

With Timezone Offset

Format: YYYY-MM-DDTHH:MM:SS±HH:MM

2024-01-01T12:00:00+00:00
2024-01-01T17:30:00+05:30  # IST
2024-01-01T07:00:00-05:00  # EST

Code Examples:

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JAVASCRIPT
1// JavaScript
2const date = new Date();
3const offset = -date.getTimezoneOffset();
4const sign = offset >= 0 ? '+' : '-';
5const hours = String(Math.floor(Math.abs(offset) / 60)).padStart(2, '0');
6const minutes = String(Math.abs(offset) % 60).padStart(2, '0');
7const iso = date.toISOString().replace('Z', `${sign}${hours}:${minutes}`);
8// 2024-01-01T12:00:00.000+00:00

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PYTHON
1# Python
2datetime.now(timezone.utc).isoformat()
3# 2024-01-01T12:00:00+00:00
4
5# With specific timezone
6from datetime import timezone, timedelta
7ist = timezone(timedelta(hours=5, minutes=30))
8datetime.now(ist).isoformat()
9# 2024-01-01T17:30:00+05:30

Date Only

Format: YYYY-MM-DD

2024-01-01

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JAVASCRIPT
1// JavaScript
2new Date().toISOString().split('T')[0];
3// 2024-01-01

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PYTHON
1# Python
2datetime.now().date().isoformat()
3# 2024-01-01

Time Only

Format: HH:MM:SS or HH:MM:SS.sss

12:00:00
12:00:00.000

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JAVASCRIPT
1// JavaScript
2new Date().toISOString().split('T')[1];
3// 12:00:00.000Z

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PYTHON
1# Python
2datetime.now().time().isoformat()
3# 12:00:00.000000

RFC 3339 Format

Format: YYYY-MM-DDTHH:MM:SS.sss±HH:MM or ...Z

2024-01-01T12:00:00.000Z
2024-01-01T12:00:00.000+00:00

Difference from ISO 8601:

• Always includes milliseconds
• Always includes timezone
• More strict specification

Code Examples:

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JAVASCRIPT
1// JavaScript
2new Date().toISOString(); // Already RFC 3339 compliant
3// 2024-01-01T12:00:00.000Z

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PYTHON
1# Python
2from datetime import datetime, timezone
3datetime.now(timezone.utc).isoformat()
4# 2024-01-01T12:00:00.000000+00:00

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GO
1// Go
2time.Now().UTC().Format(time.RFC3339Nano)
3// 2024-01-01T12:00:00.000000000Z

RFC 2822 Format

Format: Day, DD Mon YYYY HH:MM:SS ±HHMM

Mon, 01 Jan 2024 12:00:00 +0000
Mon, 01 Jan 2024 12:00:00 GMT

When to Use:

• Email headers (Date field)
• HTTP headers
• RSS feeds

Code Examples:

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JAVASCRIPT
1// JavaScript
2new Date().toUTCString();
3// Mon, 01 Jan 2024 12:00:00 GMT

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PYTHON
1# Python
2from email.utils import formatdate
3formatdate(timeval=None, localtime=False, usegmt=True)
4# Mon, 01 Jan 2024 12:00:00 GMT

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PHP
1// PHP
2date('r');
3// Mon, 01 Jan 2024 12:00:00 +0000

SQL Timestamp Formats

MySQL/MariaDB DATETIME

Format: YYYY-MM-DD HH:MM:SS

2024-01-01 12:00:00

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SQL
1-- MySQL
2SELECT NOW();
3-- 2024-01-01 12:00:00
4
5SELECT DATE_FORMAT(NOW(), '%Y-%m-%d %H:%i:%s');
6-- 2024-01-01 12:00:00

PostgreSQL TIMESTAMP

Format: YYYY-MM-DD HH:MM:SS.ssssss±TZ

2024-01-01 12:00:00.000000+00
2024-01-01 12:00:00+00

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SQL
1-- PostgreSQL
2SELECT NOW();
3-- 2024-01-01 12:00:00.000000+00
4
5SELECT CURRENT_TIMESTAMP;
6-- 2024-01-01 12:00:00.000000+00

SQLite DATETIME

Format: YYYY-MM-DD HH:MM:SS (stored as text)

2024-01-01 12:00:00

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SQL
1-- SQLite
2SELECT datetime('now');
3-- 2024-01-01 12:00:00
4
5SELECT strftime('%Y-%m-%d %H:%M:%S', 'now');
6-- 2024-01-01 12:00:00

Microsoft SQL Server

Format: YYYY-MM-DD HH:MM:SS.sss

2024-01-01 12:00:00.000

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SQL
1-- SQL Server
2SELECT GETUTCDATE();
3-- 2024-01-01 12:00:00.000
4
5SELECT FORMAT(GETUTCDATE(), 'yyyy-MM-dd HH:mm:ss.fff');
6-- 2024-01-01 12:00:00.000

Language-Specific Formats

JavaScript

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JAVASCRIPT
1// Various formats
2const date = new Date();
3
4// ISO 8601
5date.toISOString();                    // 2024-01-01T12:00:00.000Z
6
7// Locale string
8date.toLocaleString();                  // 1/1/2024, 12:00:00 PM
9
10// UTC string
11date.toUTCString();                     // Mon, 01 Jan 2024 12:00:00 GMT
12
13// Date only
14date.toLocaleDateString();              // 1/1/2024
15
16// Time only
17date.toLocaleTimeString();              // 12:00:00 PM
18
19// Custom format
20date.toLocaleString('en-US', {
21  year: 'numeric',
22  month: '2-digit',
23  day: '2-digit',
24  hour: '2-digit',
25  minute: '2-digit',
26  second: '2-digit',
27  hour12: false
28});
29// 01/01/2024, 12:00:00

Python strftime Codes

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PYTHON
1from datetime import datetime
2
3dt = datetime(2024, 1, 1, 12, 0, 0)
4
5# Common formats
6dt.strftime('%Y-%m-%d')                 # 2024-01-01
7dt.strftime('%Y-%m-%d %H:%M:%S')       # 2024-01-01 12:00:00
8dt.strftime('%Y-%m-%dT%H:%M:%SZ')      # 2024-01-01T12:00:00Z
9dt.strftime('%d/%m/%Y')                 # 01/01/2024
10dt.strftime('%m/%d/%Y')                 # 01/01/2024
11dt.strftime('%B %d, %Y')                # January 01, 2024
12dt.strftime('%A, %B %d, %Y')           # Monday, January 01, 2024
13dt.strftime('%I:%M %p')                 # 12:00 PM

PHP date() Format

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PHP
1<?php
2$timestamp = 1704110400;
3
4// Common formats
5date('Y-m-d', $timestamp);              // 2024-01-01
6date('Y-m-d H:i:s', $timestamp);       // 2024-01-01 12:00:00
7date('c', $timestamp);                  // 2024-01-01T12:00:00+00:00 (ISO 8601)
8date('r', $timestamp);                  // Mon, 01 Jan 2024 12:00:00 +0000 (RFC 2822)
9date('U', $timestamp);                  // 1704110400 (Unix timestamp)
10date('d/m/Y', $timestamp);              // 01/01/2024
11date('m/d/Y', $timestamp);              // 01/01/2024
12date('F j, Y', $timestamp);             // January 1, 2024
13date('l, F j, Y', $timestamp);         // Monday, January 1, 2024
14date('g:i A', $timestamp);              // 12:00 PM

Go Time Format

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GO
1package main
2
3import (
4    "time"
5)
6
7func main() {
8    t := time.Date(2024, 1, 1, 12, 0, 0, 0, time.UTC)
9    
10    // Standard formats
11    t.Format(time.RFC3339)              // 2024-01-01T12:00:00Z
12    t.Format(time.RFC3339Nano)          // 2024-01-01T12:00:00.000000000Z
13    t.Format(time.RFC822)               // 01 Jan 24 12:00 UTC
14    t.Format(time.RFC1123)              // Mon, 01 Jan 2024 12:00:00 UTC
15    
16    // Custom formats (using reference time: Jan 2 15:04:05 2006 MST)
17    t.Format("2006-01-02")              // 2024-01-01
18    t.Format("2006-01-02 15:04:05")    // 2024-01-01 12:00:00
19    t.Format("01/02/2006")              // 01/01/2024
20    t.Format("January 2, 2006")         // January 1, 2024
21    t.Format("3:04 PM")                 // 12:00 PM
22}

Java SimpleDateFormat

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JAVA
1import java.text.SimpleDateFormat;
2import java.util.Date;
3import java.util.TimeZone;
4
5Date date = new Date(1704110400000L);
6SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");
7sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
8
9// Common patterns
10"yyyy-MM-dd"                            // 2024-01-01
11"yyyy-MM-dd HH:mm:ss"                  // 2024-01-01 12:00:00
12"yyyy-MM-dd'T'HH:mm:ss'Z'"            // 2024-01-01T12:00:00Z
13"dd/MM/yyyy"                            // 01/01/2024
14"MM/dd/yyyy"                            // 01/01/2024
15"MMMM d, yyyy"                          // January 1, 2024
16"EEEE, MMMM d, yyyy"                   // Monday, January 1, 2024
17"h:mm a"                                // 12:00 PM

Format Conversion Quick Reference

Unix → ISO 8601

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JAVASCRIPT
1// JavaScript
2new Date(1704110400000).toISOString();
3// 2024-01-01T12:00:00.000Z

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PYTHON
1# Python
2from datetime import datetime, timezone
3datetime.fromtimestamp(1704110400, timezone.utc).isoformat()
4# 2024-01-01T12:00:00+00:00

ISO 8601 → Unix

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JAVASCRIPT
1// JavaScript
2new Date('2024-01-01T12:00:00Z').getTime();
3// 1704110400000

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PYTHON
1# Python
2from datetime import datetime
3datetime.fromisoformat('2024-01-01T12:00:00+00:00').timestamp()
4# 1704110400.0

RFC 2822 → ISO 8601

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JAVASCRIPT
1// JavaScript
2new Date('Mon, 01 Jan 2024 12:00:00 GMT').toISOString();
3// 2024-01-01T12:00:00.000Z

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PYTHON
1# Python
2from email.utils import parsedate_to_datetime
3parsedate_to_datetime('Mon, 01 Jan 2024 12:00:00 GMT').isoformat()
4# 2024-01-01T12:00:00+00:00

Best Practices

Storage Recommendations

1. Databases: Use native TIMESTAMP type with timezone support
2. APIs: Use ISO 8601 with timezone for portability
3. Internal Processing: Use Unix milliseconds for calculations
4. Logging: Use ISO 8601 with milliseconds and timezone

Timezone Handling

• Always include timezone - Avoid ambiguous timestamps
• Store in UTC - Convert to local time only for display
• Use Z for UTC - Clearer than +00:00
• Validate timezone offsets - Ensure they're within -12:00 to +14:00

Precision Selection

Common Pitfalls

❌ Avoid:

• Storing timestamps without timezone information
• Using local time for storage (always use UTC)
• Mixing different precision levels
• Hardcoding timezone offsets
• Using 32-bit integers (Year 2038 problem)

✅ Do:

• Always include timezone designators (Z or ±HH:MM)
• Store in UTC, convert to local time for display only
• Use consistent precision across your system
• Use timezone-aware datetime objects
• Use 64-bit integers for Unix timestamps

Related Tools

• Unix Timestamp Converter - Convert between formats
• Timestamp Format Builder - Create custom formats
• Timezone Converter - Handle timezone conversions
• Batch Timestamp Converter - Convert multiple timestamps

Related Guides

• ISO 8601 Format Explained
• Understanding Timezones
• Timestamp Precision Levels