Feet to Inches Converter

How to Convert Feet to Inches

To convert a length measurement from feet to inches, multiply the length value by the conversion factor. Since one foot is equal to 12 inches, you can use this formula:

The length in inches is equal to the feet multiplied by 12.

How Many Inches Are in a Foot?

There are 12 inches in one foot.

What Is a Foot?

The foot (symbol: ft), plural feet, is a unit of length in the US customary and Imperial systems, defined as exactly 12 inches or one-third of a yard, which equals exactly 0.3048 metres. The foot is one of the most commonly used units of measurement in the United States and is used alongside inches for measuring human height (e.g., 5’10” = 5 feet 10 inches), room dimensions, building heights, and elevation. In aviation, altitude is measured in feet worldwide (even in countries that use the metric system), with typical cruising altitudes of 30,000–40,000 feet. In construction and architecture in the US, building dimensions, ceiling heights, and lumber sizes are specified in feet and inches. Standard US ceiling height is 8 or 9 feet, a standard interior door is 6 feet 8 inches tall, and dimensional lumber is sold in lengths measured in feet (8, 10, 12, 14, 16 feet). Common reference points: the Statue of Liberty is 305 feet tall (including the pedestal), a basketball hoop is 10 feet high, a standard shipping container is 20 or 40 feet long, and the depth of the deep end of a typical swimming pool is about 8–12 feet.

One foot is equal to:

• 12 inches (in)
• 0.3048 metres (m)
• 30.48 centimetres (cm)
• 304.8 millimetres (mm)
• 0.333333 yards (yd)
• 0.000189394 miles (mi)

What Is a Inch?

The inch (symbol: in or ″) is a unit of length in the US customary and Imperial systems, defined as exactly 1/12 of a foot or exactly 2.54 centimetres (0.0254 metres). The inch is one of the most commonly used small-scale measurement units in the United States, used for measuring screen sizes (measured diagonally), paper sizes, pipe diameters, screw sizes, rainfall, and many everyday objects. Computer and phone screen sizes are universally stated in inches worldwide. In engineering and manufacturing in the US, dimensions are often given in inches and fractions of inches (1/2”, 1/4”, 1/8”, 1/16”, 1/32”, 1/64”) or in decimal inches (e.g., 0.375”). Screw sizes, drill bit sizes, and pipe sizes in the US system are specified in inches. Common reference points: a US quarter coin is about 1 inch in diameter, a standard piece of letter paper is 8.5 × 11 inches, the diagonal of a typical smartphone screen is 6–7 inches, and a typical laptop screen is 13–16 inches diagonal.

One inch is equal to:

• 2.54 centimetres (cm)
• 25.4 millimetres (mm)
• 0.0254 metres (m)
• 0.0833333 feet (ft)
• 0.0277778 yards (yd)
• 25,400 micrometres (μm)

Understanding Length Units

Length is one of the seven fundamental physical quantities in the International System of Units. It measures the distance between two points in space. Length is perhaps the most intuitive physical quantity, as we encounter measurements of distance and size constantly in everyday life.

Two major systems of length measurement are in common use worldwide: the metric system (used by most countries) and the US customary/Imperial system (used primarily in the United States, and partly in the United Kingdom).

The Metric System

The metric system is based on the metre, with larger and smaller units derived using decimal prefixes. This makes conversions within the metric system straightforward — simply move the decimal point:

• Kilometre (km): 1,000 metres — used for geographic distances and travel
• Metre (m): The base unit — used for room dimensions, human height, and general measurements
• Centimetre (cm): 0.01 metres — used for body measurements, small objects, and clothing sizes
• Millimetre (mm): 0.001 metres — used for engineering precision, rainfall, and small components
• Micrometre (μm): 10⁻⁶ metres — used for cell biology, thin films, and surface roughness
• Nanometre (nm): 10⁻⁹ metres — used for atoms, molecules, light wavelengths, and semiconductor features

The US Customary / Imperial System

The US customary system uses units based on historical definitions that were later standardised in terms of the metre:

• Mile (mi): 5,280 feet = 1,609.344 m — used for road distances in the US and UK
• Yard (yd): 3 feet = 0.9144 m — used in sports (football, golf) and fabric
• Foot (ft): 12 inches = 0.3048 m — used for height, altitude, and building dimensions
• Inch (in): 2.54 cm exactly — used for screen sizes, paper, and precision measurements

Key Conversion Relationships

The most important cross-system conversions to remember are:

• 1 inch = 2.54 cm (exact, by definition since 1959)
• 1 foot = 30.48 cm (exact)
• 1 yard = 0.9144 m (exact)
• 1 mile = 1.609344 km (exact)

All US customary length units are legally defined in terms of the metre, making all conversion factors between the two systems exact values with no rounding error.

Tips for Length Conversions

• Metric conversions only involve factors of 10. Each prefix step (nm → μm → mm → cm → m → km) changes by a specific power of 10.
• Inches to centimetres: Multiply by 2.54. This is the most commonly needed cross-system conversion.
• Feet to metres: Multiply by 0.3048, or approximately 0.3. For a quick estimate, multiply feet by 3 and move the decimal one place left.
• Miles to kilometres: Multiply by 1.609. A handy approximation: add 60% to the mile value (10 miles ≈ 16 km).
• Yards to metres: Multiply by 0.9144. Since 1 yard ≈ 0.914 m, yards and metres are roughly similar in size.
• Quick mental math: 1 metre ≈ 3 feet 3 inches. 1 km ≈ 0.6 miles. 100 km ≈ 62 miles.
• Interesting relationship: The Fibonacci sequence (1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89...) closely approximates the mile-to-kilometre conversion. For example, 5 miles ≈ 8 km, 8 miles ≈ 13 km, 13 miles ≈ 21 km.
• For precision work: All inch/foot/yard/mile to metric conversions are exact values, so there is no rounding error when converting between systems.

Feet to Inches Conversion Table

The following table shows conversions from feet to inches.

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