Travel & Cooking
Convert measurements for road trips, recipes, and international travel.
Free Online Unit Converters – Length, Weight, Temperature, File Size & Color
Convert units of length, weight, temperature, file size, and colors online for free.
Unit converters handle one of the most common micro-tasks in daily life: translating a number from one system to another. Whether you need km to miles for a road trip, Celsius to Fahrenheit for a recipe, kg to lbs for a fitness app, or HEX to RGB for a CSS file — each converter here gives you an instant answer with no ads, no signup, and no friction.
Every converter includes an all-units comparison table so you can see your value in every supported unit at once, not just the pair you selected. This makes it easier to understand scale and choose the right unit for your purpose — especially useful when working across metric and imperial systems or between SI decimal and IEC binary file sizes.
Length Converter
Convert between 12 length units — km to miles, meters to feet, cm to inches — with an all-units comparison table.
Weight Converter
Convert between 11 weight units — kg to lbs, stone to kg, grams to ounces, and carats — with instant results.
Temperature Converter
Convert between 8 temperature scales including Celsius, Fahrenheit, Kelvin, and Rankine with a reference points table.
File Size Converter
Convert between 12 file size units including SI decimal (KB/MB/GB) and IEC binary (KiB/MiB/GiB) side by side.
Color Converter
Convert between HEX, RGB, and HSL color formats with a visual 2D color picker and one-click CSS copy.
Random Number Generator
Generate cryptographically secure random numbers, roll dice, flip coins, or pick items from a custom list.
Popular Workflow Paths
Design & Development
Convert color codes and file sizes for CSS, assets, and storage planning.
What You Can Do In This Category
Length & Distance
Convert km to miles, meters to feet, cm to inches, and more across 12 units including nautical miles and light years.
Weight & Mass
Switch between kg, lbs, stone, grams, ounces, carats, and three types of tons — with full cross-unit comparison.
File Size (SI & IEC)
Understand the MB vs MiB difference and convert between 12 file size units in both decimal and binary standards.
Color Formats
Convert HEX, RGB, and HSL with a visual color picker and one-click CSS copy — built for designers and developers.
Frequently Asked Questions
- What is the difference between MB and MiB?
- MB (megabyte) uses powers of 1,000 — 1 MB = 1,000,000 bytes — the SI standard used by hard drives and cloud storage. MiB (mebibyte) uses powers of 1,024 — 1 MiB = 1,048,576 bytes — the IEC binary standard used by RAM and operating systems. Windows reports file sizes in MiB but labels them MB, causing the common confusion where a 1 TB drive shows as ~931 GB.
- How do I convert Celsius to Fahrenheit without a calculator?
- The exact formula is °F = (°C × 9/5) + 32. A quick mental approximation: double the Celsius value and add 30 (e.g., 20°C → 70°F — actual is 68°F). For exact results, use the temperature converter above.
- What color format should I use in CSS — HEX, RGB, or HSL?
- All three work in modern CSS. HEX is most compact and what design tools export. RGB is easiest to manipulate programmatically. HSL is the most intuitive for building color palettes since you can adjust lightness without changing the hue. The color converter supports all three.