Free Decimal to Hex Converter Online
Convert decimal numbers to hexadecimal instantly in your browser — no server needed.
Input
Output
What Is Decimal to Hexadecimal Conversion?
If you've ever stared at a CSS color picker wondering what #FF5733 actually means in decimal, you're not alone. Converting between decimal and hexadecimal is one of those tasks developers run into constantly — whether you're setting colors, reading memory addresses, or debugging low-level code. This tool handles the math for you right in the browser, so you can focus on the actual problem. The MDN Number.toString() docs explain how JavaScript does this natively, and hex notation is central to the W3C CSS Color specification.
Hexadecimal is essential in web development (CSS colors like #FF5733 -- see this guide to hex colors on the web), memory addresses, MAC addresses, and low-level programming. This tool converts decimal integers to uppercase hexadecimal instantly, supporting multiple values at once.
How to Use This Tool
Enter Decimal Numbers
Type or paste one decimal number per line in the left editor. Click Sample to load examples, or Upload a text file.
View Hexadecimal Output
The right panel updates automatically with the hexadecimal representation of each decimal number. Output uses uppercase letters (A-F).
Copy or Download
Click Copy to copy the hex output to your clipboard, or Download to save it as a text file.
Conversion Examples
Here are some common decimal to hexadecimal conversions:
Decimal Input
Hexadecimal Output
Frequently Asked Questions
How do I convert decimal to hexadecimal step by step?
Divide the decimal number by 16 repeatedly and write down the remainders. Each remainder (0-15) maps to a hex digit (0-9, A-F). Read the remainders bottom-up. For example, 255 ÷ 16 = 15 remainder 15, so hex is FF. The MDN Number.toString(16) method does this in one call.
How do I convert a decimal RGB value to a hex color code?
Convert each of the three RGB values (0-255) to two-digit hex and concatenate them. For example, RGB(255, 87, 51) becomes #FF5733. This tool converts each component individually. See the W3C CSS Color spec for full details.
Is my data sent to a server?
No. Everything runs locally in your browser using JavaScript. Nothing leaves your machine — you can verify this in the Network tab of your browser DevTools.
Can this tool handle very large numbers?
Yes. It uses JavaScript BigInt internally, so there's no precision limit. Paste numbers of any length and get exact hex output.
Why is hexadecimal so common in programming?
Each hex digit represents exactly 4 binary bits, making it a compact way to display binary data. That's why you see hex everywhere: HTML color codes, memory addresses, MAC addresses, and byte-level data inspection.
Related Tools
Learn more: W3C CSS Color specification, ASCII code chart, and the MDN Number.toString documentation.