How to Use This Tool
Enter a Value
Type the number you want to convert into the input field. Decimals and scientific notation (like 1.5e3) are supported.
Choose Your Units
Pick a From unit and a To unit from the dropdowns. Use the swap button to flip them instantly.
Read the Result
The converted value appears instantly below the inputs. Click Copy to put it on your clipboard.
See All Conversions
Scroll down to see the same value converted into every other supported unit at once, so you can compare them all in one glance.
Frequently Asked Questions
Is this tool really free?
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Yes, completely free with no limits and no sign-up. Everything runs in your browser with no server costs.
Is my data sent to a server?
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No. All conversion math happens directly in your browser. Nothing you type is ever sent anywhere.
What units are supported?
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13 units: Kilometer, Meter, Centimeter, Millimeter, Micrometer, Nanometer, Mile, Yard, Foot, Inch, Nautical Mile, Light Year, and Astronomical Unit.
How accurate are the conversions?
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The tool uses standard conversion factors and displays up to 10 significant figures. Results are accurate for everyday, educational, and professional use.
Can I see all conversions at once?
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Yes. Below the main result, the tool shows the same value converted into every other unit in a scrollable list so you can compare them all at a glance.
Can I swap the From and To units?
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Yes. Click the swap button between the two dropdowns to flip them instantly. The result recalculates right away.
Does it support decimals and scientific notation?
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Yes. You can type values like 0.5, 3.14, or 1.5e3 (which means 1500). The tool handles all standard number formats.
What is a Nautical Mile?
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A nautical mile is 1,852 meters and is used in aviation and maritime navigation. It is slightly longer than a regular (statute) mile of 1,609 meters.
What is an Astronomical Unit?
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An astronomical unit (AU) is the average distance from the Earth to the Sun, roughly 149.6 billion meters. It is used to measure distances within our solar system.
What is a Light Year?
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A light year is the distance light travels in one year, roughly 9.46 trillion kilometers. It is used to measure distances between stars and galaxies.
What Is Length Converter?
Length Converter is a free tool that converts between 13 length and distance units right in your browser. It covers metric (kilometer down to nanometer), imperial (mile, yard, foot, inch), nautical, and even astronomical scales (light year and astronomical unit). Nothing you type is ever sent anywhere - all math runs locally on your device.
The result updates live as you type, and a full conversion table shows the same value in every other unit at once. Use the swap button to flip your units instantly, or copy the result to your clipboard in one click.
Features Explained
13 Length Units
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Convert between Kilometer, Meter, Centimeter, Millimeter, Micrometer, Nanometer, Mile, Yard, Foot, Inch, Nautical Mile, Light Year, and Astronomical Unit.
Metric Units
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Full metric scale from Kilometer (1,000 meters) down to Nanometer (one billionth of a meter), covering everyday, scientific, and engineering measurements.
Imperial Units
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Mile, Yard, Foot, and Inch for everyday measurements in countries that use the imperial system.
Astronomical Units
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Light Year and Astronomical Unit for distances across space - from the Earth-to-Sun distance to interstellar scales.
Nautical Mile
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Used in aviation and maritime navigation. One nautical mile equals 1,852 meters, slightly longer than a regular mile.
Instant Conversion
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The result updates live as you type. There is no Convert button to click - you see the answer the moment your input changes.
All Conversions at Once
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Below the main result, a scrollable table shows the same value converted into every other unit simultaneously. Great for comparing across scales.
Swap Button
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Click the swap button between the From and To dropdowns to flip them instantly. The result recalculates right away.
Copy to Clipboard
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Click Copy to put the converted value on your clipboard instantly, ready to paste into a document, spreadsheet, or message.
100% Browser-Based
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All conversion math runs directly in your browser. Nothing you type is ever sent to any server - complete privacy.
Who Is This Tool For?
Students
Convert between metric and imperial units for physics, math, and science homework and lab reports.
Teachers
Show unit conversions in real time during lessons and help students understand the relationship between different measurement systems.
Engineers
Convert dimensions between metric and imperial systems when working with international specifications, drawings, and standards.
Architects
Convert building measurements between feet, meters, and inches when working with plans from different countries or standards.
Construction Workers
Quickly convert between feet, inches, meters, and centimeters when reading plans or measuring materials on site.
Scientists
Convert between metric scales from kilometers down to nanometers for research, experiments, and publications.
Travelers
Convert between miles and kilometers to understand road signs, distances, and maps in countries that use a different system.
Runners and Athletes
Convert race distances between miles and kilometers to compare times and plan training across both measurement systems.
DIY and Home Improvement
Convert measurements when following instructions, buying materials, or working with tools marked in a different unit system.
Real Estate Agents
Convert property dimensions and lot sizes between feet, meters, and acres for international buyers and listings.
Pilots and Navigators
Convert between nautical miles, kilometers, and statute miles for flight planning and maritime navigation.
Astronomers
Convert between light years, astronomical units, and kilometers when discussing distances in space.
Graphic Designers
Convert between inches, centimeters, and millimeters when preparing print layouts and understanding physical dimensions.
Tailors and Fashion Designers
Convert body measurements between inches and centimeters when working with international sizing charts.
Woodworkers
Convert between inches, feet, centimeters, and millimeters when reading plans or measuring cuts.
3D Modelers
Convert dimensions when importing models or assets created in different unit systems.
Shipping and Logistics
Convert package dimensions between inches and centimeters for international shipping labels and regulations.
Surveyors
Convert field measurements between meters, feet, and yards for land surveys and boundary documentation.
Healthcare Professionals
Convert patient measurements between inches and centimeters for medical records, growth charts, and equipment sizing.
Photographers
Convert focal lengths and sensor sizes between millimeters and inches when comparing camera specifications.
Hobbyists and Makers
Convert dimensions when following international project plans, tutorials, or kit instructions.
Writers and Journalists
Convert distances for international stories so readers in different countries can understand the scale.
Parents
Convert your child's height between feet/inches and centimeters for growth tracking and medical visits.
Anyone
Quickly convert any length or distance for any reason - curiosity, homework, travel, shopping, or work.
Tips for Best Results
Use the All Conversions table
Scroll below the main result to see the same value in every other unit at once. This is the fastest way to compare across scales.
Use the swap button
Click the swap button between the dropdowns to flip From and To instantly instead of changing both dropdowns manually.
Try scientific notation for large numbers
For very large or very small values, type scientific notation like 1.5e6 (1,500,000) or 2.5e-9 (0.0000000025) instead of counting zeros.
Copy the result in one click
Click Copy next to the result to put the value on your clipboard, ready to paste into a spreadsheet, document, or message.
Know your common conversions
1 inch = 2.54 cm, 1 foot = 30.48 cm, 1 mile = 1.609 km, 1 yard = 0.914 m. The tool handles these and many more automatically.
Metric prefix pattern
Metric units follow a simple pattern: kilo (1,000), centi (1/100), milli (1/1,000), micro (1/1,000,000), nano (1/1,000,000,000). The tool covers all of these.
Nautical miles for navigation
If you work in aviation or maritime, use Nautical Mile. One nautical mile equals one minute of latitude, which is why it is standard for navigation.
Light years for space distances
Use Light Year or Astronomical Unit when working with space distances. One AU is the Earth-to-Sun distance; one light year is about 63,241 AU.
Decimals are fully supported
You can type values like 3.14, 0.5, or 12.75. The tool handles decimal precision up to 10 significant figures.
Privacy is built in
Nothing you type is ever sent to any server. All math runs in your browser, so your measurements stay completely private.
Privacy & Security
This tool runs 100% in your browser. Your files stay entirely on your own device. Nothing is uploaded, nothing is shared, and no server, advertiser, or third party has access to your files.
If a tool saves your work on your own device, you can remove it at any time using the Clear All button. Some tools rely on an external service to return their result; in those cases, only the minimum data required for the request is sent, and never your files or content. Any ads shown on this page run in an isolated frame and cannot read, touch, or transmit anything you upload, paste, type, or download here. Advertisers may see standard visit information like your IP address and which page you're on, as described in our Privacy Policy, but your data itself stays fully under your control.
