Timestamp Converter Guide: Everything You Need to Know About Time Formats

If you’ve ever debugged an API response, analyzed log files, or worked with databases, you’ve encountered timestamps. That cryptic string of numbers like 1706745600 or 2024-02-01T00:00:00Z can feel opaque until you understand what they represent—and how to convert between formats.

This guide breaks down timestamp conversion in practical terms, whether you’re debugging a production issue or building date-sensitive features.

What Is a Timestamp?

A timestamp is a numeric representation of a specific moment in time. The most common formats you’ll encounter:

Unix Timestamp (Epoch Time): The number of seconds (or milliseconds) since January 1, 1970, 00:00:00 UTC. This format dominates programming because it’s timezone-agnostic—a single integer represents the same moment anywhere on Earth.

ISO 8601: An internationally recognized string format like 2024-02-01T14:30:00Z. The T separates date and time, while Z indicates UTC. Human-readable but precise.

Human-Readable Dates: Formats like “February 1, 2024” or “01/02/2024” that vary by region. Great for display, problematic for storage or comparison.

Our Timestamp Converter handles all these formats seamlessly.

Why Timestamps Matter in Programming

Every developer eventually needs timestamp conversion. Here’s where it surfaces most:

API Development: REST APIs frequently return dates as Unix timestamps for compactness. GraphQL often prefers ISO 8601. You’ll constantly translate between these.

Database Operations: Most databases store dates internally as timestamps or similar numeric values. SQL queries frequently filter or sort by timestamp columns.

Log Analysis: Server logs typically use timestamps for correlation. Converting these to readable dates helps diagnose issues.

User Interfaces: Users expect localized, human-readable dates. Behind the scenes, you’re working with Unix time.

Common Timestamp Formats Explained

Unix Timestamp (Seconds)

The classic Unix timestamp counts seconds from the epoch. As I write this:

1706745600 seconds since January 1, 1970

Unix Timestamp (Milliseconds)

JavaScript and many modern APIs use milliseconds instead:

1706745600000 milliseconds since epoch

Notice the extra three digits—this catches many developers off guard when integrating between systems.

ISO 8601 with Timezones

The format expands to include timezone offsets:

2024-02-01T14:30:00+05:00

This represents 2:30 PM in a timezone 5 hours ahead of UTC. The Z shorthand means UTC (zero offset).

How to Convert Timestamps

Modern timestamp converters simplify this dramatically. Here’s the typical workflow:

Input Formats

Most converters accept:

• Unix timestamp (seconds or milliseconds)
• ISO 8601 strings
• Natural language (“yesterday”, “next Monday”)
• Specific date formats

Output Options

Convert to your preferred format:

• Unix timestamp (seconds or milliseconds)
• ISO 8601
• Custom formatted strings
• Relative time (“2 hours ago”)

Our Timestamp Converter tool supports bidirectional conversion across all common formats.

Handling Timezones: The Tricky Part

Timezones cause the most timestamp-related headaches. Here’s what you need to know:

UTC vs. Local Time

Unix timestamps are always UTC. When you see “2024-02-01 14:30”, that’s ambiguous without timezone context. Always clarify whether times are local or UTC in your system.

Daylight Saving Time

DST transitions create duplicate or skipped timestamps. Between 2:00 AM and 3:00 AM (clocks spring forward), certain times don’t exist. In autumn, they occur twice. Databases handle this differently—know your system’s approach.

Timezone Databases

The IANA Time Zone Database (tzdb) is the standard reference. It updates periodically to reflect political timezone changes. Keep your systems updated—the same timestamp can map to different local times before and after database revisions.

Best Practices

• Store everything in UTC when possible
• Convert to local time only for display
• Use timezone-aware libraries (moment-timezone, date-fns-tz, pytz)
• Document your timezone assumptions in code comments

Programming Language Examples

JavaScript

// Convert timestamp to Date
const date = new Date(1706745600000);

// Get current timestamp
const now = Date.now();

// Format as ISO string
date.toISOString(); // "2024-02-01T00:00:00.000Z"

Python

from datetime import datetime

# Convert timestamp to datetime
dt = datetime.fromtimestamp(1706745600)

# Current timestamp
now = datetime.now().timestamp()

# Format as ISO
dt.isoformat()

SQL (PostgreSQL)

-- Unix timestamp to timestamp type
SELECT to_timestamp(1706745600);

-- Timestamp to Unix epoch
SELECT EXTRACT(EPOCH FROM timestamp '2024-02-01');

Real-World Use Cases

API Response Parsing

{
  "created_at": 1706745600,
  "updated_at": "2024-02-01T12:30:00Z"
}

You’ll need to convert both to a consistent format for display or comparison.

Database Queries

-- Find records from the last 24 hours
SELECT * FROM events 
WHERE created_at > NOW() - INTERVAL '24 hours';

-- Convert stored timestamp for display
SELECT TO_CHAR(created_at, 'YYYY-MM-DD HH24:MI:SS') FROM events;

Log Analysis

Server logs often look like:

[2024-02-01 14:30:01] INFO: Request processed

Timestamp converters help you correlate these with application timestamps.

Common Pitfalls to Avoid

Millisecond vs. Second Confusion: JavaScript uses milliseconds; most other systems use seconds. A difference of 1000x can cause dates to appear decades off.

Timezone Mismatch: Storing local times without timezone info leads to bugs. A timestamp stored as “2024-02-01 14:30” in New York represents a different moment than the same string in Tokyo.

Ignoring DST: Applications running across daylight saving transitions need timezone-aware date handling. Naive date libraries often produce wrong results.

Epoch Overflow: The Year 2038 problem affects 32-bit systems using signed 32-bit integers for Unix time. Most modern systems use 64-bit and are safe, but legacy integration can still cause issues.

Advanced Techniques

Batch Conversion

For large datasets, avoid individual conversions. Use array operations or database-level transformations.

Timezone Conversion Formula

To convert Unix timestamp to a specific timezone:

target_time = UTC_time + timezone_offset

Note that offsets change throughout the year due to DST—you need the timezone identifier (America/New_York), not just the offset (-05:00).

Relative Time Calculations

Many applications show relative times (“5 minutes ago”). This requires comparing the current timestamp with the stored timestamp:

const diff = Date.now() - timestamp;
const minutes = Math.floor(diff / 60000);

Tools and Resources

For quick conversions, our Timestamp Converter handles the heavy lifting. Other useful tools in this space include:

• Date Picker for selecting dates visually
• Days Between Dates for calculating date ranges
• Unit Converter for various measurement conversions

Frequently Asked Questions

Key Takeaways

• Unix timestamps represent seconds (or milliseconds) since January 1, 1970—timezone-neutral and computationally simple
• ISO 8601 provides human-readable, internationally recognized date formatting
• Always clarify timezone context to avoid subtle bugs
• Store in UTC, convert to local time only for display purposes
• Watch for millisecond vs. second differences when integrating between systems

Master timestamp conversion with our free Timestamp Converter tool.