How to Convert Lengths
Enter the value you want to convert in the Value field.
Select the unit you are converting from in the From dropdown.
Select the unit you want to convert to in the To dropdown.
Click Convert to see the result.
Key Features
90+ Units Covered
Supports metric SI prefixes, imperial/US customary, nautical, astronomical, and dozens of historical and scientific units.
Precise Results
Uses exact base multipliers for each unit. Results show full precision without unnecessary trailing zeros, and switch to scientific notation automatically for extremely large or small values.
Works Offline
All conversions run entirely in your browser using JavaScript. No internet connection is needed after the page loads.
Privacy-First
No data is ever sent to a server. Your measurements stay on your device.
Privacy & Security
This tool runs entirely in your browser. No values are transmitted to any server, stored, or logged. It is safe to use with sensitive measurements or in offline environments.
Frequently Asked Questions
How accurate are the conversions?
Each unit is defined by an exact multiplier relative to the meter. The conversion formula is: result = value × (from unit in meters) ÷ (to unit in meters). Results are shown to 12 significant figures before trailing zeros are removed.
What is the base unit used for conversions?
All conversions go through the meter as the base unit. Each unit is stored as its exact value in meters, so any pair of units can be converted without a lookup table.
Why does the result show scientific notation?
Scientific notation is used automatically when the result is smaller than 0.0001 or larger than 1,000,000,000,000,000 (1e15). This keeps the output readable for extreme conversions such as meters to Planck lengths or parsecs to millimeters.
What is the difference between micron and micrometer?
They are the same unit. A micron is an informal name for the micrometer (1×10⁻⁶ m). Both are listed separately because both names are in common use.
What is a light year in meters?
One light year is approximately 9.461×10¹⁵ meters — the distance light travels in one year in a vacuum.