Skip to main content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.


The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Unit Conversion

Unit conversion is a multi-step process that involves multiplication or division by a numerical factor, selection of the correct number of significant digits, and rounding. This multi-step process is presented in NIST SP 1038 - 2006 (Section 4.4), including a rounding procedure for technical documents, specifications, and other applications such packaged goods in the commercial marketplace and temperature. Common conversion factors are also listed (Section 5).

Unit Conversion Example

  • unit conversion
    "If you have an amount of unit of A, how much is that in unit B?"
  • Dimensional Analysis
  • Principle - quantities defined as equalities
  • Conversion Factor: an expression for the relationship between units.

4 Steps

  1. What do you have?
    1. Starting Units
  2. What do you want?
    1. Desired Units
  3. Identify Conversion Factor(s)
    1. Ratio or Linking Units
  4. Cancel Units Where You Can and Do the Math

Setting Up the Problem

unit conversion

unit conversion





Convert 5 m to ? cm

unit conversion









Created January 13, 2010, Updated November 15, 2019