Free Unit Conversion Tools
Weight, length, and temperature converters with instant results, reference tables, and step-by-step formulas. 3 tools, all free.
Weight Converter
Convert between pounds, ounces, grams, kilograms, stone, and tons instantly with formulas and reference output.
Use tool →Length Converter
Convert between inches, centimeters, millimeters, meters, kilometers, feet, yards, and miles.
Use tool →Fahrenheit to Celsius
Convert between °F and °C with step-by-step formulas. Includes Kelvin and common temperature labels.
Use tool →Data Size Converter
Convert between bytes, KB, MB, GB, TB, and PB. Supports both decimal (SI) and binary (IEC) systems.
Use tool →Why Unit Conversion Tools Matter
If you have ever tried to follow a recipe from another country, shop for clothes online from an international brand, or check the weather while traveling abroad, you have run into the imperial-versus-metric divide. The United States still relies heavily on pounds, inches, and Fahrenheit, while most of the world uses kilograms, centimeters, and Celsius. These differences trip people up every day — whether you are a student working through a science assignment, a home cook scaling a British recipe, or a shopper trying to figure out if that jacket will actually fit. Our unit conversion tools give you instant, accurate answers right in your browser so you can stop guessing and get back to what you were doing.
Weight: Pounds, Ounces, and the Metric System
The imperial weight system — pounds and ounces — is deeply embedded in everyday American life, from grocery store labels to postal scales. But if you are shipping a package internationally, reading nutritional info from a European product, or doing any kind of scientific work, you will need metric units like grams and kilograms. Our Pounds to Ounces converter handles the math instantly and includes a quick-reference table so you can scan common values at a glance. It also shows conversions to grams and kilograms, making it easy to jump between systems without opening a second tool.
Length: Inches, Centimeters, and Everything in Between
Length conversions come up constantly — measuring furniture for a room, checking the dimensions of a phone case, or converting height from feet and inches to centimeters for a medical form. One inch equals exactly 2.54 centimeters, but doing that multiplication in your head gets old fast, especially with awkward numbers. The Inches to Centimeters converter does the work for you and also displays the result in feet, meters, and millimeters so you have every measurement you might need in one place. A built-in reference table covers the most commonly looked-up values.
Temperature: Fahrenheit, Celsius, and Kelvin
Temperature conversion is arguably the trickiest of the three because the formula is not a simple multiplication — you have to subtract 32, multiply by 5, and divide by 9 to go from Fahrenheit to Celsius (or work the formula in reverse). Our Fahrenheit to Celsius converter shows the step-by-step math so you actually understand what is happening, not just the final number. It also displays the Kelvin equivalent and labels common temperatures like freezing, boiling, and normal body temperature for context. More converters — including kilograms to pounds, miles to kilometers, and liters to gallons — are coming soon.
Frequently Asked Questions
When should I use metric versus imperial units?
It depends on your audience and context. In the United States, imperial units (pounds, inches, Fahrenheit) are standard for everyday use, while metric units (kilograms, centimeters, Celsius) are used in science, medicine, and most other countries. If you are communicating internationally or doing academic work, metric is usually the safer choice. Our converters make it easy to switch between systems whenever you need to.
What are the basic conversion formulas?
For weight, 1 pound equals 16 ounces (or about 453.6 grams). For length, 1 inch equals exactly 2.54 centimeters. For temperature, the formula is °C = (°F - 32) × 5/9 to go from Fahrenheit to Celsius, and °F = (°C × 9/5) + 32 to go the other direction. Each of our tools shows these formulas step by step so the math is transparent.
Why do Fahrenheit and Celsius use different scales?
The two scales were invented independently. Daniel Fahrenheit designed his scale in 1724 using a brine solution as the zero point, with water freezing at 32°F and boiling at 212°F. Anders Celsius created a simpler scale in 1742 with water freezing at 0°C and boiling at 100°C. Because the starting points and intervals differ, converting between them requires more than simple multiplication — you need the offset formula described above.
Do these tools store my data or require an account?
No. Every converter runs entirely in your browser. We do not collect, store, or transmit any of the values you enter. There are no accounts, no sign-ups, and no usage limits. Just open a tool and start converting.