Unit & Data Converters
A free collection of fast, private online converters for developers and designers. Convert timestamps, colors, number bases, CSS units, data sizes, temperatures, everyday units, Roman numerals, and Morse code — everything runs locally in your browser, with no signup and no data ever uploaded to a server.
All Converters
Unix Timestamp Converter
Convert Unix epoch timestamps to human-readable dates and back, with live current time, UTC/local, and ISO 8601.
Color Code Converter
Convert color codes between HEX, RGB, and HSL with a live visual picker and one-click copy.
Number Base Converter
Convert numbers between decimal, binary, hexadecimal, and octal in real time, with BigInt support for huge integers.
CSS Unit Converter
Convert CSS units — px, rem, em, %, pt, vw, vh — both directions with a live table and configurable base sizes.
Data Size Converter
Convert bytes, KB, MB, GB, TB with decimal (SI, 1000) and binary (IEC, 1024) units side by side.
Temperature Converter
Convert between Celsius, Fahrenheit, Kelvin, and Rankine in real time — type in any field and the others update instantly.
Unit Converter
Convert length, weight, volume, area, and speed between all common metric and imperial units — inches↔cm, kg↔lbs, miles↔km.
Roman Numeral Converter
Convert numbers 1–3,999 to Roman numerals and decode Roman numerals back, with a step-by-step breakdown.
Binary / Hex Encoder
Convert text to binary, hexadecimal, octal, or ASCII codes and decode back — bidirectional and instant.
Morse Code Translator
Translate text to Morse code and decode Morse back to text, with audio playback at adjustable speed.
Why use an online converter?
Many everyday conversions are easy to get wrong by hand. Is one GB equal to 1000 or 1024 MB? How many rem is 24px at a 16px root font size? What's #6366f1 in RGB? The answers depend on standards and base values that are easy to mix up. These converters do the math for you instantly and in both directions, so you can convert a timestamp, a color, a number base, a CSS unit, or a data size without second-guessing the result. We've gathered the conversions developers and designers reach for most often into one place, so you don't need a separate tool — or a calculator and a reference table — for each one.
Unix Timestamp Converter
Turn epoch seconds or milliseconds into readable dates and back, with live timezone handling — perfect for debugging logs and APIs.
Color Code Converter
Move between HEX, RGB, and HSL with a visual picker — ideal for matching brand colors and CSS values.
Number Base Converter
Convert between decimal, binary, hexadecimal, and octal in real time — a must for low-level and bitwise work.
CSS Unit Converter
Translate px, rem, em, pt, %, vw, and vh against your chosen base font size and viewport for pixel-accurate layouts.
Data Size Converter
Convert bytes through petabytes with decimal (SI) and binary (IEC) units side by side — finally see GB vs GiB clearly.
Private and free — nothing leaves your browser
Every converter here runs entirely as client-side JavaScript. When you convert bytes to KB, px to rem, or hex to rgb, the calculation happens on your own device — nothing is sent to a server, stored, or logged. That makes these tools safe to use even with sensitive values, and it means they work instantly with no network round-trip. There's no account to create, no software to install, and no usage limit. Just open the page and start converting.
Frequently asked questions
What unit converters does NJHTools offer?↓
NJHTools offers ten free online converters: a Unix timestamp converter, a color code converter (HEX, RGB, HSL), a number base converter (decimal, binary, hexadecimal, octal), a CSS unit converter (px, rem, em, %, vw, vh), a data size converter (bytes, KB, MB, GB, TB), a temperature converter (Celsius, Fahrenheit, Kelvin, Rankine), a unit converter (length, weight, volume, area, speed), a Roman numeral converter, a binary/hex text encoder, and a Morse code translator.
Are these converters free and private?↓
Yes. Every converter is completely free with no signup, and all conversion runs 100% locally in your browser. Your input is never uploaded to or stored on any server.
Can I convert bytes to KB, MB, or GB online?↓
Yes. The Data Size Converter converts between bytes, KB, MB, GB, TB and more, showing both decimal (SI, 1000) and binary (IEC, 1024) units side by side so you can see whether a GB means 1000 or 1024 MB.
Do I need to install anything to use these converters?↓
No. All converters run directly in your web browser with no installation, no extension, and no account. Just open the page and start converting.
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