ft to ft-us | Convert Foot to US Survey Foot

Foot to US Survey Foot Conversion Formula Example What is a Foot (ft)?How Many Inches Make a Foot?The History of the Foot Measurement How Is the Foot Used Today?What is a US Survey Foot (ft-us)?Where Did the US Survey Foot Come From?Why Was the US Survey Foot Replaced?Why Did This Small Difference Cause Big Problems?What is the imperial system?Foot to US Survey Foot Conversion Table

Foot to US Survey Foot Conversion Formula

To convert from Foot (ft) to US Survey Foot (ft-us), use the following formula:

$\textbf{ US Survey Foot} \text{ (ft-us)}$

$= \frac{1}{1.000002}\times \textbf{ Foot} \text{ (ft)}$

$= 0.999998000003999992\times \textbf{ Foot} \text{ (ft)}$

Example

Let's convert 5 Foot (ft) to US Survey Foot (ft-us).

Using the formula:

$5 \times 0.999998000003999992 = 4.99999000001999996$

Therefore, 5 Foot (ft) is equal to $4.99999000001999996$ US Survey Foot (ft-us).

What is a Foot (ft)?

The foot (ft) is a standard unit of length in the Imperial and U.S. customary systems of measurement.

The plural form is feet.

How Many Inches Make a Foot?

There are exactly 12 inches in a foot.

This fundamental conversion is the cornerstone of the Imperial and U.S. customary systems. It's a standard used everywhere, from measuring personal height to completing construction projects.

Additionally, it's helpful to know that 3 feet make one yard.

The History of the Foot Measurement

The origin of the "foot" as a unit of measurement is quite literal—it was historically based on the average length of a human foot.

Ancient civilizations, such as the Greeks, Romans, and Egyptians, often used body parts as a basis for measurement.

Because the actual length of a person's foot could vary, so did the measurement. This led to many inconsistencies until the foot was officially standardized.

How Is the Foot Used Today?

Although most of the world uses the metric system, the foot is still an official unit of length in the United States.

It is also commonly used in countries such as the United Kingdom and Canada, particularly for measuring height, altitude, and property dimensions.

To establish a global standard, the international foot was defined in 1959 as being exactly 0.3048 meters.

This precise conversion is crucial for international science, trade, and engineering.

What is a US Survey Foot (ft-us)?

The US Survey Foot is a unit of length historically used for land surveying in the United States.

It is very close in length to the international foot, equaling approximately 1.000002 international feet (ft). The plural form is US Survey Feet.

Where Did the US Survey Foot Come From?

The origin of the US Survey Foot dates back to the Mendenhall Order of 1893. This order defined the relationship between the meter and US customary units.

It established that 1 meter is precisely equal to 39.37 inches. From this relationship, the US Survey Foot was derived, defined as 1200/3937 meters.

This definition differs slightly from the international foot, which was established in 1959 and is defined as exactly 0.3048 meters.

Why Was the US Survey Foot Replaced?

To simplify measurements and prevent confusion, the National Institute of Standards and Technology (NIST) and the National Geodetic Survey (NGS) made a critical change.

They officially retired the U.S. Survey Foot on December 31, 2022.

Surveying and mapping applications in the United States will now use the international foot. This critical change helps unify the National Spatial Reference System (NSRS) and prevents costly errors in large-scale projects.

Why Did This Small Difference Cause Big Problems?

While the difference between a US Survey Foot and an international foot is minuscule—only about two parts per million—it becomes significant over large distances.

For every mile, the discrepancy adds up to approximately 1/8 inch.

This minor error may not be significant for a backyard fence. However, for massive construction projects and infrastructure development, such as bridges that cross state lines, the accumulated error can lead to severe misalignments and costly mistakes.

What is the imperial system?

The imperial system is a system of measurement that was first defined in the British Weights and Measures Act of 1824. It's known for using units like inches, feet, pounds, and gallons. While most of the world now uses the metric system, the imperial system remains the official system of measurement in the United States and is still used in specific contexts in other countries, such as the United Kingdom and Canada.

Foot to US Survey Foot Conversion Table

Here are some quick reference conversions from Foot (ft) to US Survey Foot (ft-us):

Feet	US Survey Feet
0.000001 ft	$9.99998000003999992\times 10^{-7}$ ft-us
0.001 ft	$0.000999998000003999992$ ft-us
0.1 ft	$0.0999998000003999992$ ft-us
1 ft	$0.999998000003999992$ ft-us
2 ft	$1.999996000007999984$ ft-us
3 ft	$2.999994000011999976$ ft-us
4 ft	$3.999992000015999968$ ft-us
5 ft	$4.99999000001999996$ ft-us
6 ft	$5.999988000023999952$ ft-us
7 ft	$6.999986000027999944$ ft-us
8 ft	$7.999984000031999936$ ft-us
9 ft	$8.999982000035999928$ ft-us
10 ft	$9.99998000003999992$ ft-us
20 ft	$19.99996000007999984$ ft-us
30 ft	$29.99994000011999976$ ft-us
40 ft	$39.99992000015999968$ ft-us
50 ft	$49.9999000001999996$ ft-us
100 ft	$99.9998000003999992$ ft-us
1000 ft	$999.998000003999992$ ft-us
10000 ft	$9999.98000003999992$ ft-us

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