If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Lesson 1: Units of length

# Getting a sense of inches and feet

Explore inches and feet as units of length. Learn to visualize an inch with a quarter or thumb and understand a foot equals 12 inches. The video includes examples of when to use inches or feet for measuring various objects. Created by Sal Khan.

## Want to join the conversation?

• What is a cm?
• A cm, or centimeter, is one-hundredth (1/100) of a meter.
So if you have 1 centimeter, you have 0.01 meters; and 100 centimeters equals 1 meter. When converting from centimeters to meters, you just move the decimal toward the left by two place values. And when converting from meters to centimeters, you multiply by 100.

Centimeters is a very small unit of measurement. In the previous video, Sal Khan says that a centimeter is only the width of a fingernail, while a meter is the length of a guitar.
• Why does 8feet look deep in the pool?
• the water can change how deep any body of water looks. Also for a pool 8ft is pretty deep.
• How does 12 inches=1 foot
• Don't try looking for a logical explenation.

Before meters and grams people used units based of various body parts or items they could find. Among those belonged inches and feet. Inches are the length of three grains of barley and on the other hand feet are as the name suggests the length of a human foot. But as you may know feet and seeds aren't always the same length. So the local goverments and rulers (no pun intended) created standards, which were placed at public places to prevent frequent market scams caused by unstandardized measurements.

Alongside these standardized lengths also came simpler conversions of such lengths so that each unit of length would fit inside each other neatly by multiplying or deviding with integers (1, 2, 3 ...).

So to summerize units were created using various items or body parts which were later on standardized and assainged interger conversions between those units to simplify the work with them.