What Is Foot (US Survey)?
The foot US survey is a special version of the foot that was used mainly by surveyors in the United States to measure land and map large areas. It is almost the same as the normal foot used today, but it is very slightly longer.
Definition
The foot US survey is a unit for measuring length. It is used to say how long or how far something is, especially on land maps and survey plans.
By definition:
- 1 foot US survey = 1200 / 3937 meter exactly
- This is about 0.3048006096 meter
The normal or international foot is exactly 0.3048 meter. So the US survey foot is only about 0.0000006096 meter longer than the international foot. This difference is less than a hair in width, so in daily life you will not notice it, but it matters in very large land measurements.
History / Origin
The idea of the foot as a unit of length is very old and comes from human body parts, like the length of a person’s foot. Over time, different countries made their own exact versions of the foot.
In the United States in the 1800s, the government needed a clear and exact length to use for surveys, maps, and land sales. In 1893 the United States set the yard, and so also the foot, using a careful link to the meter. This older definition led to the length that later became known as the US survey foot.
In 1959 the United States and several other countries agreed on a new standard, the international yard and the international foot. The international foot was fixed at exactly 0.3048 meter. Most uses in the US switched to this new international foot.
However, for land surveying and some mapping systems in the United States, the old definition was kept and was then called the US survey foot. This kept old map data and land records consistent.
In 2019 US agencies decided to stop using the US survey foot for new work and use only the international foot. This change took effect in 2023, but many older maps and land descriptions still use the US survey foot.
Symbol & Abbreviation
The most common symbol for the foot US survey is the same as for any foot:
- ft for foot or feet
- A single quote mark can also mean foot, for example 10′ = 10 feet
Because there are two slightly different feet, some people use special labels to make the meaning clear:
- ft (US survey) or ftUS for the US survey foot
- ft (int) for the international foot
In normal life, you will just see ft. The longer names are mainly used in technical work by surveyors, engineers, and map makers.
Current Use Around the World
The US survey foot was used mostly in the United States and in some parts of its territories. It was not widely used in other countries.
Today:
- The US survey foot is being phased out from new surveying and mapping work in the United States.
- The international foot is now the only foot that US federal agencies want for new projects.
- Older maps, property boundaries, and state plane coordinate systems may still be in US survey feet.
- Surveyors and engineers still need to understand it so they can match new data with old records correctly.
Most other countries use the metric system, especially the meter, and do not use the US survey foot.
Example Conversions
Below are some easy conversions to help you see how long a foot US survey is.
From US survey foot to meters and centimeters
- 1 ft (US survey) ≈ 0.3048006096 m ≈ 30.48006096 cm
- 10 ft (US survey) ≈ 3.048006096 m
- 100 ft (US survey) ≈ 30.48006096 m
- 1000 ft (US survey) ≈ 304.8006096 m
From meters to US survey feet
To change meters to US survey feet, divide by 0.3048006096.
- 1 m ≈ 3.280833333 ft (US survey)
- 10 m ≈ 32.80833333 ft (US survey)
- 100 m ≈ 328.0833333 ft (US survey)
US survey foot vs international foot
- 1 ft (US survey) ≈ 1.000002 ft (international)
- 10000 ft (US survey) is about 0.02 ft longer than 10000 ft (international)
This shows that the difference is tiny for small distances but can add up over many miles.
Related Units
The foot US survey is connected to several other length units, both in the same system and in the metric system.
- International foot (ft): The modern standard foot used in most places. Exactly 0.3048 meter. Very close to the US survey foot.
- Yard (yd): A length unit where 1 yard = 3 feet. For US survey units, 1 yd (US survey) = 3 ft (US survey).
- Mile (mi): A long distance unit. In US survey terms, 1 mile = 5280 ft (US survey).
- Chain: A surveying unit often used in land work. 1 chain = 66 ft (US survey).
- Link: A smaller surveying unit. 1 chain = 100 links, so 1 link = 0.66 ft (US survey).
- Meter (m): The main metric length unit. 1 ft (US survey) ≈ 0.3048006096 m.
- Centimeter (cm): A smaller metric unit. 1 m = 100 cm. 1 ft (US survey) ≈ 30.48006096 cm.
FAQs
What is the US survey foot in simple words?
The US survey foot is a special version of the foot used in older American land surveys and maps. It is almost the same as the normal foot, but a tiny bit longer.
How does the US survey foot differ from the international foot?
The international foot is exactly 0.3048 meter. The US survey foot is exactly 1200 divided by 3937 meters, which is about 0.3048006096 meter. The difference is about 0.0000006096 meter per foot, so it only matters over large distances.
Do people still use the US survey foot today?
It is no longer used for new federal surveying and mapping projects in the United States. However, many old maps, property descriptions, and some state coordinate systems still use US survey feet, so surveyors must know it.
Why was the US survey foot kept for so long?
It was kept to match older land records and maps that were already made with this unit. If the unit had changed, many coordinates and property lines would no longer line up correctly.
How can I tell if a map uses US survey feet or international feet?
Look at the map legend or notes. They may say “US survey feet”, “ft (US survey)”, or “international feet”. If it is not clear, surveyors often check with the data source or look at official documentation.
Should I use the US survey foot in new projects?
For most new work, especially in the United States, you should use the international foot or, even better, metric units like the meter, unless a law or contract clearly requires US survey feet.