21K Tools – Free Online Calculators & Utility Tools

File Converter Tool

Convert between 100+ file formats instantly

Our File Converter tool at 21K Tools is a comprehensive solution for all your file conversion needs. Whether you're working with documents, images, audio, or video files, our converter handles it all with precision and speed.

With support for over 100 file formats, you can easily convert PDF to Word, JPG to PNG, MP4 to MP3, and much more. The tool preserves formatting and quality while ensuring fast processing times, even for large files.

Perfect for professionals, students, and anyone who works with digital files regularly. No software installation required - everything happens securely in your browser.

Key Features

Supports documents, images, audio, video, and archive formats
Batch conversion for multiple files at once
Cloud-based processing - no software installation needed
Military-grade encryption for file security
Optimized for fast conversion even with large files
Preserves formatting and quality during conversion
Works on all devices including mobile phones

Image Resizer Tool

Resize, compress, and optimize images effortlessly

The Image Resizer from 21K Tools is a powerful yet simple solution for all your image editing needs. Whether you're preparing photos for social media, optimizing images for your website, or adjusting pictures for printing, our tool makes it easy.

With smart compression algorithms, you can significantly reduce file sizes without noticeable quality loss. The bulk processing feature lets you resize multiple images at once, saving you hours of work.

Our tool supports all popular image formats including JPG, PNG, GIF, SVG, and WebP. The intuitive interface makes professional-grade image optimization accessible to everyone.

Key Features

Resize by dimensions or percentage
Smart compression with quality control
Bulk processing for multiple images
Preserve aspect ratio or custom crop
Format conversion between all major types
Preview before downloading
No quality loss with advanced algorithms

AI Content Generator

Create high-quality content with artificial intelligence

Our AI Content Generator at 21K Tools leverages the latest in artificial intelligence to help you create compelling content in seconds. Powered by advanced language models, this tool can generate articles, product descriptions, marketing copy, and more.

Whether you're a content creator, marketer, or business owner, our AI tool helps overcome writer's block and boosts productivity. The generated content is SEO-friendly and can be customized to match your brand voice.

With support for multiple languages and content types, this is the ultimate writing assistant for professionals and creatives alike. Save hours of work while maintaining high quality standards.

Key Features

Powered by GPT-4 technology
Generate articles, blogs, ads, and more
SEO-optimized content suggestions
Multiple language support
Tone and style customization
Content length control
Plagiarism-free original content

Age Calculator

Calculate exact ages down to the day

The Age Calculator from 21K Tools provides precise age calculations in years, months, and days. Perfect for determining eligibility, planning events, or simply satisfying curiosity about exact ages.

Our calculator automatically accounts for leap years and varying month lengths to deliver accurate results. You can calculate ages from past dates or project ages into the future for planning purposes.

The intuitive interface makes it easy to use, with clear visual representation of the results. Whether you're calculating human ages, pet ages, or the age of historical events, our tool handles it with precision.

Key Features

Calculates exact age in years, months, and days
Automatically accounts for leap years
Future age projection capability
Simple, intuitive interface
Works on all devices including mobile
No registration required
Instant results with no waiting

Interest Calculator

Calculate loan and investment interest with precision

The Interest Calculator from 21K Tools is a comprehensive financial tool that helps you understand the true cost of loans or the potential growth of investments. Whether you're planning to take out a mortgage, evaluating credit card interest, or projecting investment returns, our calculator provides clear insights.

With support for both simple and compound interest calculations, you can model various financial scenarios. The tool includes amortization schedules to show how payments are applied over time, helping you make informed financial decisions.

Perfect for personal finance management, business planning, or educational purposes. The visual charts make complex financial concepts easy to understand at a glance.

Key Features

Simple and compound interest calculations
Detailed amortization schedules
Interactive charts for visualization
Multiple compounding frequency options
Extra payment calculations
Export results to PDF or CSV
Mobile-friendly interface

PDF Toolkit

Complete solution for all PDF needs

The PDF Toolkit from 21K Tools is your comprehensive solution for working with PDF documents. Whether you need to merge multiple files, split large documents, compress file sizes, or convert to other formats, our toolkit has you covered.

Our tool maintains document formatting and quality while providing fast processing. The intuitive interface makes professional PDF manipulation accessible to everyone, from students to business professionals.

With advanced security features, you can be confident your documents are handled safely. All processing happens in your browser - no files are uploaded to our servers, ensuring complete privacy.

Key Features

Merge multiple PDFs into one document
Split PDFs by pages or extract specific pages
Compress PDFs without noticeable quality loss
Convert to/from Word, Excel, PowerPoint, JPG
Password protection and encryption
OCR for scanned documents
Batch processing capabilities

Unit Converter

Convert between hundreds of measurement units

The Unit Converter from 21K Tools is an essential tool for students, professionals, and anyone who needs to work with different measurement systems. Convert between metric and imperial units, or between any of hundreds of specialized units across various categories.

Our converter includes up-to-date currency exchange rates, making it perfect for travelers and international business. The history feature lets you track your recent conversions, and you can save favorites for quick access.

With support for length, weight, volume, temperature, area, speed, time, and more, this is the most comprehensive unit converter available online. The clean interface makes conversions quick and easy.

Key Features

100+ unit types across all categories
Real-time currency conversion
Conversion history tracking
Favorite units for quick access
Mobile-optimized interface
Copy results with one click
Share conversions via link

Time Calculator

Calculate durations, add/subtract time, and manage time zones

The Time Calculator from 21K Tools is a versatile tool for all your time-related calculations. Calculate the duration between two dates or times, add or subtract time intervals, and convert between time zones with ease.

Perfect for project planning, work scheduling, or simply calculating how many days until an important event. Our calculator accounts for daylight saving time changes and leap years to ensure accurate results.

The time zone converter is ideal for coordinating with teams or contacts across the globe. With support for hundreds of locations worldwide, you'll always know the correct local time.

Key Features

Calculate duration between dates/times
Add or subtract time intervals
Time zone conversion for 500+ locations
Daylight saving time awareness
Workday calculations excluding weekends
Countdown timers
Shareable results

Welcome to 21K Tools

Featured Tools

File Converter

Image Resizer

AI Content Generator

Age Calculator

Interest Calculator

PDF Toolkit

Unit Converter

Time Calculator

File Converter Tool

Key Features

Image Resizer Tool

Key Features

AI Content Generator

Key Features

Age Calculator

Key Features

Interest Calculator

Key Features

PDF Toolkit

Key Features

Unit Converter

Key Features

Time Calculator

Key Features