Unit Converters
Length Converter
Convert between 11 length units with standards-based factors.
Enter the values and review the result.
Enter a length and choose source and target units.
Quick answers
What this calculator answers
- Scope: Converts among 11 SI, U.S. customary, and nautical length units.
- Method: Converts the source value to meters, then derives the selected target without reciprocal constants.
- Precision: Uses standards-based factors and displays up to 12 significant digits with defined scientific-notation thresholds.
Transparency note
Accuracy and limitations
Calzivo tools are built for practical estimates, conversions, and checks. Some tools use standard formulas or simplified assumptions, and results can be affected by input accuracy, rounding, units, local rules, or changing official requirements.
Results depend on the values you enter and any simplified assumptions used by the tool. Verify important results before making decisions or submitting official information.
Reference check
Sources and references
These references provide background context for the topic. They do not replace official advice or documents for personal decisions.
- NIST Guide to the SI, Appendix B: Conversion Factors
National Institute of Standards and Technology
- NIST Guide to the SI, Appendix B.8: Factors Listed Alphabetically
National Institute of Standards and Technology
- The International System of Units (SI Brochure)
Bureau International des Poids et Mesures
How to Use This Tool
Use these steps to enter the right inputs and interpret the result correctly.
Enter a non-negative length using a complete decimal or scientific-notation value.
Choose the source and target units, or use Swap to reverse them without changing the amount.
Read or copy the canonical result and review the substituted base-unit calculation.
Related Tools
Use Unit Converter for a compact length, mass, or temperature workflow; use the specialist calculators for deeper unit coverage.
Unit Converter
Convert common length, mass, and temperature units.
Weight Converter
Convert mass units with avoirdupois and ton distinctions.
Area Calculator
Calculate area for rectangles, squares, triangles, circles, trapezoids, parallelograms, and ellipses with formulas and square units.
Volume Calculator
Calculate volume for cubes, boxes, cylinders, spheres, cones, pyramids, and prisms with cubic unit conversions.
Related Guides
Background reading and explanations related to Length Converter.
Frequently Asked Questions
Common questions about Length Converter and how to read the result.
Which length units are supported?
Nanometers, micrometers, millimeters, centimeters, meters, kilometers, inches, feet, yards, miles, and nautical miles are supported.
Are the inch, foot, yard, and mile factors exact?
Yes. The calculator uses the international definitions: 1 inch is 0.0254 meter, 1 foot is 0.3048 meter, 1 yard is 0.9144 meter, and 1 mile is 1609.344 meters.
How is a nautical mile different?
The international nautical mile is exactly 1852 meters. It is a nautical navigation unit, not the 1609.344-meter international land mile.
Can I enter a negative length?
No. Zero is accepted, including a normalized -0, but ordinary negative values are rejected for this everyday physical-length workflow.
Why can a round trip differ slightly?
Calculations retain the unrounded Number result, but the visible and copied result uses up to 12 significant digits. Re-entering that rounded display can introduce a very small difference.