Unix Timestamp Cheat Sheet: Quick Conversions, Formulas & Developer Shortcuts

When you're working with time in development, speed matters. You don’t always want to Google how to convert a timestamp or calculate durations. That’s where a Unix timestamp cheat sheet becomes incredibly useful.

In this guide, you’ll get a complete, practical, and developer-focused cheat sheet for Unix timestamps—covering formulas, quick conversions, code snippets, and real-world shortcuts.

For instant conversions while working, use this tool: https://www.mydevtoolhub.com/tools/unix-timestamp-converter

What is a Unix Timestamp? (Quick Recap)

A Unix timestamp is the number of seconds since January 1, 1970 (UTC).

Example:

• 1700000000

Quick Conversion Formulas

Current Timestamp

Math.floor(Date.now() / 1000);

Timestamp → Date

new Date(timestamp * 1000);

Date → Timestamp

Math.floor(new Date(date).getTime() / 1000);

Time Duration Cheat Sheet

Seconds in Time Units

• 1 minute = 60 seconds
• 1 hour = 3600 seconds
• 1 day = 86400 seconds
• 1 week = 604800 seconds

Common Calculations

1 Day from Now

const oneDay = Math.floor(Date.now() / 1000) + 86400;

7 Days Ago

const sevenDaysAgo = Math.floor(Date.now() / 1000) - (7 * 86400);

Ready-to-Use Snippets

Check Expiry

function isExpired(expiry) {
  return Math.floor(Date.now() / 1000) > expiry;
}

Compare Two Dates

function isAfter(t1, t2) {
  return t1 > t2;
}

Format Timestamp to Readable Date

function format(ts) {
  return new Date(ts * 1000).toISOString();
}

Database Cheat Sheet (MongoDB)

Store Timestamp

{
  createdAt: Math.floor(Date.now() / 1000)
}

Query Last 24 Hours

const now = Math.floor(Date.now() / 1000);

 db.logs.find({
  createdAt: { $gte: now - 86400 }
});

Sort by Latest

db.logs.find().sort({ createdAt: -1 });

API Cheat Sheet

Request Example

GET /api/posts?after=1700000000

Response Example

{
  "createdAt": 1700000000
}

Frontend Cheat Sheet (React)

Display Date

new Date(timestamp * 1000).toLocaleString();

Countdown Logic

const remaining = target - Math.floor(Date.now() / 1000);

Debugging Cheat Sheet

Log Both Formats

console.log({
  timestamp,
  iso: new Date(timestamp * 1000).toISOString()
});

Detect Milliseconds vs Seconds

if (timestamp.toString().length === 13) {
  console.log("Milliseconds");
}

Common Mistakes (Quick Fixes)

Mistake 1: Using Milliseconds

// Fix
Math.floor(Date.now() / 1000);

Mistake 2: Timezone Confusion

Solution:

• Always use UTC
• Convert only for display

Mistake 3: Storing Strings

// Avoid
"1700000000"

// Use
1700000000

Real-World Shortcuts

Token Expiry (1 Hour)

const expiry = now + 3600;

Cache Expiry (5 Minutes)

const cacheExpiry = now + 300;

Last 30 Days Filter

const last30Days = now - (30 * 86400);

Advanced Tips

Use UTC Everywhere

Never rely on local time.

Index Timestamp Fields

Improves database performance.

Use Numbers for Storage

Avoid strings.

When to Use Unix Timestamp

Use it for:

• Backend logic
• Databases
• APIs
• Logging systems

When NOT to Use It

Avoid for:

• Direct UI display
• User-facing formats

FAQs

What is the easiest way to convert timestamps?

Use this tool:

https://www.mydevtoolhub.com/tools/unix-timestamp-converter

Why divide by 1000?

Because JavaScript uses milliseconds.

Can timestamps be negative?

Yes, for dates before 1970.

Conclusion

This Unix timestamp cheat sheet is designed to save you time and improve your productivity. Instead of repeatedly searching for conversions and formulas, you now have everything in one place.

Use these shortcuts, snippets, and best practices in your daily development workflow to build faster and more reliable applications.

For instant conversions and debugging, use:

https://www.mydevtoolhub.com/tools/unix-timestamp-converter

Bookmark this guide and use it whenever you're working with time-related logic.