Unit Converter

Convert between imperial and metric units instantly with step-by-step explanations. Choose from three categories:

  • Length — inches, feet, yards, miles, millimeters, centimeters, meters, kilometers
  • Weight — ounces, pounds, tons, grams, kilograms, metric tons
  • Volume — teaspoons, tablespoons, fluid ounces, cups, pints, quarts, gallons, milliliters, liters

Formulas Used

Inches to centimeters

Feet to meters

Miles to kilometers

How to Use This Converter

  1. Select a category (Length, Weight, or Volume) using the buttons at the top
  2. Enter a value in the input field
  3. Choose your units using the From and To dropdowns — use the swap button to reverse direction
  4. See the result immediately with a full step-by-step breakdown showing the conversion factor

When You’ll Need Unit Conversion

Unit conversion comes up constantly in trade work, especially when dealing with materials and specifications that mix imperial and metric measurements:

Plumbing

Pipe sizes in the United States are measured in inches (1/2”, 3/4”, 1”), but many imported fittings and fixtures use metric dimensions. Converting between the two is critical to ensure proper connections and avoid leaks. Water flow rates may be specified in gallons per minute or liters per minute depending on the fixture manufacturer.

HVAC

Duct measurements, refrigerant quantities, and airflow calculations often require converting between imperial and metric. An HVAC technician might need to convert BTUs to kilowatts when working with equipment from different manufacturers, or convert cubic feet per minute (CFM) to metric equivalents for international specifications.

Carpentry and Construction

Lumber dimensions, sheet goods, and hardware often come in mixed systems. A carpenter might work with 4x8 sheets of plywood (feet) while drilling holes sized in millimeters for European-style cabinet hardware. Converting between fractions of an inch and millimeters is an everyday task.

Concrete and Masonry

Concrete is ordered in cubic yards in the US but mixed using ratios that may reference kilograms of cement per cubic meter. Rebar sizes use a numbering system in the US (based on eighths of an inch) but millimeters internationally.

Electrical Work

Wire gauges in the US use the AWG (American Wire Gauge) system, but conductor sizes in many other countries are specified in square millimeters. Being able to convert between measurement systems helps electricians work with international equipment and specifications.

Tips for Accurate Conversions

  • Don’t round too early — carry extra decimal places through intermediate calculations and only round the final answer
  • Check reasonableness — a meter is about 3 feet, a kilogram is about 2.2 pounds, a liter is a bit more than a quart
  • Know your precision needs — rough framing can tolerate 1/8” variance, but finish work or machining may require thousandths of an inch

Want to strengthen the math skills behind unit conversion? Read our tutorials on Decimals and Ratios and Proportions for complete explanations with worked examples and practice problems.