FreeKit is a collection of free online tools for developers, SEO professionals, designers, students, content creators, and everyday users.

Are all tools completely free?

Yes. Every tool on FreeKit is free to use without subscriptions or hidden charges.

Do I need to create an account?

No. You can use all tools instantly without creating an account.

No. Most tools process data locally in your browser, and we do not permanently store your inputs.

Can I use FreeKit on mobile devices?

Yes. Every tool is fully responsive and works on smartphones, tablets, laptops, and desktop computers.

How often are new tools added?

We regularly add new tools and improve existing ones based on user feedback and industry needs.

Which browsers are supported?

FreeKit supports all modern browsers, including Chrome, Edge, Firefox, Safari, and other Chromium-based browsers.

Can I share these tools with others?

Absolutely. You are welcome to share FreeKit with friends, colleagues, students, and your team.

How do I convert between metric and imperial units?

Our unit converter handles metric-to-imperial conversions automatically. Simply select the category (e.g., Length), choose the source unit (e.g., Kilometers) and the target unit (e.g., Miles), enter a value, and the result appears instantly. The conversion factors are built into the tool, so you never need to memorize them.

Why does temperature conversion use a different formula than other units?

Unlike length or weight where units are related by a simple multiplication factor (e.g., 1 km = 1,000 m), temperature scales have different zero points. Celsius sets 0° at water's freezing point, Fahrenheit at 32°, and Kelvin at absolute zero (−273.15°C). This means converting between them requires both multiplication and addition/subtraction, not just a ratio. Our converter handles these special formulas automatically.

How accurate are the conversions?

Our converter uses internationally accepted conversion factors with up to 10 significant digits of precision. For everyday use — cooking, travel, fitness, construction — this precision is more than sufficient. Results are displayed with up to 6 decimal places, and trailing zeros are removed for cleaner output.

Can I convert data storage units like MB to GB?

Yes! Our Data Storage category converts between Bits, Bytes, Kilobytes (KB), Megabytes (MB), Gigabytes (GB), Terabytes (TB), and Petabytes (PB). Note that we use the decimal (SI) definition where 1 KB = 1,000 Bytes, which is the standard used by storage manufacturers. Some operating systems use binary (1 KiB = 1,024 Bytes), which may cause slight differences in displayed sizes.

What units of speed can I convert between?

The Speed category supports Meters per second (m/s), Kilometers per hour (km/h), Miles per hour (mph), Knots (nautical miles per hour), Feet per second (ft/s), and Mach (speed of sound at sea level). This covers everything from everyday driving speeds to aviation and aerospace applications.

Is my data sent to a server when I use this converter?

No. The unit converter runs entirely in your browser using client-side JavaScript. Every calculation happens locally on your device. No values you enter are transmitted to any server, stored in any database, or shared with third parties. When you close or refresh the page, all data is gone.

How do I quickly swap the from/to units?

Click the swap button (the double arrow icon) between the “From” and “To” sections. This instantly reverses both the unit selections and recalculates the conversion with the previous result as the new input. It is a handy shortcut when you need the inverse conversion.

What is the difference between US customary units and imperial units?

While they share many unit names (inches, feet, gallons), US customary and British Imperial systems differ in volume definitions. A US gallon is 3.785 liters, while an Imperial gallon is 4.546 liters. For length and weight, the two systems are largely identical. Our converter uses US customary definitions for volume, which is the standard in most online contexts.

Can I convert area units like square meters to acres?

Yes. The Area category handles all common area conversions including Square Millimeters, Square Centimeters, Square Meters, Square Kilometers, Square Inches, Square Feet, Square Yards, Acres, and Hectares. This is useful for real estate, land measurement, construction, and agriculture.

Does this converter support real-time conversion as I type?

Yes. The converter updates the result instantly with every keystroke — there is no need to press a submit button or hit Enter. As soon as you type a number in the input field, the converted value is calculated and displayed in real time, making it fast and efficient for comparing multiple values.

Unit Converter

Convert between units of length, weight, temperature, and more.

BeginnerCalculatorsFreev1.0.0Updated Jun 10, 2025

Unit Converter

Select a category and convert between units instantly

FROMEnter a value and select the source unit

Value

Unit

TOConverted result

Result

Type a value to convert

Unit

Quick Reference: Length

Common conversions for length

From	Equals	Factor
1 km	0.6214 mi	1.60934
1 mi	1.60934 km	0.62137
1 m	3.28084 ft	0.3048
1 ft	30.48 cm	0.03281
1 in	2.54 cm	0.3937
1 yd	0.9144 m	1.09361

100% Private — Runs in Your Browser

All unit conversions happen locally using JavaScript. Your numbers are never sent to any server, stored, or shared. Close the tab and your data is gone.

How to Use the Unit Converter

Converting between units is quick and easy. Follow these steps to get accurate results in seconds:

Choose a category — Select from Length, Weight/Mass, Temperature, Volume, Area, Speed, or Data Storage using the tabs at the top.
Enter a value — Type the number you want to convert in the “Value” input field. The result updates instantly as you type.
Select units — Pick the source unit in the “From” dropdown and the target unit in the “To” dropdown.
Read the result — The converted value appears in the result field below, along with a conversion details line showing the full equation.
Swap units — Click the “Swap Units” button to instantly reverse the conversion direction, including swapping the input and result values.

Features

Seven unit categories: Length, Weight, Temperature, Volume, Area, Speed, and Data Storage
Six to nine units per category covering both metric and imperial systems
Real-time conversion — results update instantly as you type, no submit button needed
Special temperature formulas with proper offset handling (not simple ratios)
One-click swap button to reverse from/to units and carry over the result
Quick reference table showing common conversions for each category
Conversion details display showing the full from = to equation
Supports very large and very small numbers with scientific notation
100% browser-based — no server, no data collection, no API calls
Fully responsive design for mobile, tablet, and desktop screens

Conversion Categories Explained

Length

Convert between millimeters, centimeters, meters, kilometers, inches, feet, yards, and miles. Essential for construction, travel, and everyday measurements.

Weight / Mass

Convert between milligrams, grams, kilograms, ounces, pounds, stones, and tons. Useful for cooking, shipping, fitness, and science.

Temperature

Convert between Celsius, Fahrenheit, Kelvin, and Rankine. Uses special formulas since temperature scales have different zero points.

Volume

Convert between milliliters, liters, gallons, quarts, pints, cups, fluid ounces, and tablespoons. Perfect for cooking and baking.

Area

Convert between square millimeters, meters, kilometers, inches, feet, yards, acres, and hectares. Used in real estate and land measurement.

Speed

Convert between meters per second, km/h, mph, knots, feet per second, and Mach. Common in travel, aviation, and physics.

Data Storage

Convert between bits, bytes, kilobytes, megabytes, gigabytes, terabytes, and petabytes. Both decimal (SI) and binary (KiB/MiB) prefixes supported.

Common Use Cases

Travel Planning

Convert miles to kilometers or vice versa to understand distances in different countries. Check speed limits between mph and km/h.

Cooking & Baking

Convert between cups, tablespoons, fluid ounces, and milliliters when following international recipes. Switch between Fahrenheit and Celsius for oven temperatures.

Fitness Tracking

Convert body weight between pounds and kilograms. Track running distance in miles or kilometers. Convert pace between min/mile and min/km.

Construction & DIY

Convert between feet, inches, and meters for building materials. Calculate area in square feet or square meters for flooring and paint coverage.

Science & Engineering

Use SI unit conversions for physics and chemistry calculations. Convert temperature between Celsius, Kelvin, and Rankine for thermodynamics.

Digital Storage

Understand file sizes by converting between MB, GB, and TB. Check internet speeds by converting between Mbps and MB/s.

Real Estate

Convert property sizes between square feet, square meters, acres, and hectares. Compare listings across countries using different measurement systems.

Shipping & Logistics

Convert package weights between ounces, pounds, and kilograms. Calculate dimensions in inches or centimeters for international shipping labels.

Tips for Unit Conversion

A helpful mental shortcut: 1 inch is approximately 2.5 cm, and 1 mile is approximately 1.6 km.
For temperature, remember that −40° is the same in both Celsius and Fahrenheit — it is the only point where the two scales intersect.
When converting area, remember you must square the linear conversion factor. For example, 1 m ≈ 3.28 ft, so 1 m² ≈ 10.76 ft².
Data storage labels on hard drives use decimal (1 GB = 1 billion bytes) while operating systems often display binary (1 GiB = 1.07 billion bytes). This explains why a 500 GB drive shows as ~465 GB in your computer.
Need to calculate percentages alongside unit conversions? Try our Percentage Calculator for all common percentage math.
Working with colors and need to convert between HEX, RGB, and HSL formats? Use our Color Converter for instant color code translations.
Tracking your health metrics? Our BMI Calculator accepts weight in both pounds and kilograms.
Scheduling meetings across time zones? Our Time Zone Converter helps you find the perfect time for everyone.
The metric system is based on powers of 10, making it easy to convert by simply moving the decimal point. Kilo- (1,000), centi- (0.01), and milli- (0.001) are the most common prefixes.
For quick weight conversion, remember: 1 kg ≈ 2.2 lb. So a 70 kg person weighs about 154 lb.

Metric vs Imperial Systems

Metric System (SI)

The metric system is used by nearly every country in the world and is the standard in science, medicine, and international trade. It is based on powers of 10, with base units like meters (length), kilograms (mass), liters (volume), and degrees Celsius (temperature). Converting within the metric system simply requires moving the decimal point.

Imperial / US Customary System

The imperial system is primarily used in the United States, with some usage in the UK and Canada. Units include inches, feet, yards, miles (length), ounces, pounds (weight), gallons, quarts (volume), and degrees Fahrenheit (temperature). Conversions between units often involve non-round numbers, such as 1 foot = 12 inches or 1 mile = 5,280 feet.

When to Use Each System

Use metric for scientific work, international travel, and anything requiring precision. Use imperial for everyday US measurements like driving distances, body weight, and recipes. Our converter bridges both systems seamlessly, so you never have to worry about which one to use.

A Brief History

The metric system originated in France during the 1790s revolution and was designed to be universal and easy to use. The imperial system evolved from ancient Roman and Anglo-Saxon units over centuries. Today, only three countries (the US, Liberia, and Myanmar) have not fully adopted the metric system.

Frequently Asked Questions

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From

Equals

Factor

1 km

0.6214 mi

1.60934

1 mi

1.60934 km

0.62137

1 m

3.28084 ft

0.3048

1 ft

30.48 cm

0.03281

1 in

2.54 cm

0.3937

1 yd

0.9144 m

1.09361

How to Use the Unit Converter

Converting between units is quick and easy. Follow these steps to get accurate results in seconds:

Choose a category — Select from Length, Weight/Mass, Temperature, Volume, Area, Speed, or Data Storage using the tabs at the top.

Enter a value — Type the number you want to convert in the “Value” input field. The result updates instantly as you type.

Select units — Pick the source unit in the “From” dropdown and the target unit in the “To” dropdown.

Read the result — The converted value appears in the result field below, along with a conversion details line showing the full equation.

Swap units — Click the “Swap Units” button to instantly reverse the conversion direction, including swapping the input and result values.

Features

Seven unit categories: Length, Weight, Temperature, Volume, Area, Speed, and Data Storage

Six to nine units per category covering both metric and imperial systems

Real-time conversion — results update instantly as you type, no submit button needed

Special temperature formulas with proper offset handling (not simple ratios)

One-click swap button to reverse from/to units and carry over the result

Quick reference table showing common conversions for each category

Conversion details display showing the full from = to equation

Supports very large and very small numbers with scientific notation

100% browser-based — no server, no data collection, no API calls

Fully responsive design for mobile, tablet, and desktop screens

Conversion Categories Explained

Length

Convert between millimeters, centimeters, meters, kilometers, inches, feet, yards, and miles. Essential for construction, travel, and everyday measurements.

Weight / Mass

Convert between milligrams, grams, kilograms, ounces, pounds, stones, and tons. Useful for cooking, shipping, fitness, and science.

Temperature

Convert between Celsius, Fahrenheit, Kelvin, and Rankine. Uses special formulas since temperature scales have different zero points.

Volume

Convert between milliliters, liters, gallons, quarts, pints, cups, fluid ounces, and tablespoons. Perfect for cooking and baking.

Area

Convert between square millimeters, meters, kilometers, inches, feet, yards, acres, and hectares. Used in real estate and land measurement.

Speed

Convert between meters per second, km/h, mph, knots, feet per second, and Mach. Common in travel, aviation, and physics.

Data Storage

Convert between bits, bytes, kilobytes, megabytes, gigabytes, terabytes, and petabytes. Both decimal (SI) and binary (KiB/MiB) prefixes supported.

Common Use Cases

Travel Planning

Convert miles to kilometers or vice versa to understand distances in different countries. Check speed limits between mph and km/h.

Cooking & Baking

Convert between cups, tablespoons, fluid ounces, and milliliters when following international recipes. Switch between Fahrenheit and Celsius for oven temperatures.

Fitness Tracking

Convert body weight between pounds and kilograms. Track running distance in miles or kilometers. Convert pace between min/mile and min/km.

Construction & DIY

Convert between feet, inches, and meters for building materials. Calculate area in square feet or square meters for flooring and paint coverage.

Science & Engineering

Use SI unit conversions for physics and chemistry calculations. Convert temperature between Celsius, Kelvin, and Rankine for thermodynamics.

Digital Storage

Understand file sizes by converting between MB, GB, and TB. Check internet speeds by converting between Mbps and MB/s.

Real Estate

Convert property sizes between square feet, square meters, acres, and hectares. Compare listings across countries using different measurement systems.

Shipping & Logistics

Convert package weights between ounces, pounds, and kilograms. Calculate dimensions in inches or centimeters for international shipping labels.

Tips for Unit Conversion

A helpful mental shortcut: 1 inch is approximately 2.5 cm, and 1 mile is approximately 1.6 km.

For temperature, remember that −40° is the same in both Celsius and Fahrenheit — it is the only point where the two scales intersect.

When converting area, remember you must square the linear conversion factor. For example, 1 m ≈ 3.28 ft, so 1 m² ≈ 10.76 ft².

Data storage labels on hard drives use decimal (1 GB = 1 billion bytes) while operating systems often display binary (1 GiB = 1.07 billion bytes). This explains why a 500 GB drive shows as ~465 GB in your computer.

Need to calculate percentages alongside unit conversions? Try our Percentage Calculator for all common percentage math.

Working with colors and need to convert between HEX, RGB, and HSL formats? Use our Color Converter for instant color code translations.

Tracking your health metrics? Our BMI Calculator accepts weight in both pounds and kilograms.

Scheduling meetings across time zones? Our Time Zone Converter helps you find the perfect time for everyone.

The metric system is based on powers of 10, making it easy to convert by simply moving the decimal point. Kilo- (1,000), centi- (0.01), and milli- (0.001) are the most common prefixes.

For quick weight conversion, remember: 1 kg ≈ 2.2 lb. So a 70 kg person weighs about 154 lb.