What Is Acre (US Survey)?
The acre (US survey) is a unit used to measure land area in the United States for surveying and mapping. It is almost the same as a normal acre but very slightly larger. Surveyors used it to mark property lines, farms, and large pieces of land on official maps.
Definition
An acre (US survey) is a measure of surface area. It is used mainly on land, not for small things like rooms or tables.
By definition:
- 1 acre (US survey) = 43,560 square US survey feet
- This is about 4,046.8726 square meters
- This is about 0.4047 hectare
The difference between an acre (US survey) and the more common international acre is very small. The US survey acre is only a tiny bit larger, a difference too small to notice without exact math.
History / Origin
The word acre comes from old English and once meant the area a pair of oxen could plow in one day. Over time, countries tried to make this size fixed and clear so everyone could agree on land sizes.
In the United States, surveyors needed very exact units to draw maps and set land borders, especially when the country was being divided into townships and sections. The US survey foot was defined for this work, and the acre used with it became the acre (US survey).
This special acre was used in:
- The Public Land Survey System for dividing public land
- Old land grants and farm boundaries
- State and county mapping records
Later, the international foot and the international acre were defined in a slightly different way. They are almost the same as the survey versions, but not exactly, which is why the US survey acre kept its own name.
Symbol & Abbreviation
The acre (US survey) usually uses the same short form as an acre, but sometimes people add extra words to make it clear which one they mean.
- Common symbol: ac
- Sometimes written as: ac (US) or acre (US survey)
On modern technical charts or documents, you may see notes like 22US survey acre22 or 22acre, US survey22 to avoid confusion with the international acre.
Current Use Around the World
Today, most of the world uses square meters and hectares for land area. The acre (US survey) is mainly a US concept.
Typical places you still find the acre (US survey):
- Old American land deeds and titles
- Historic survey maps and government land records
- Some property and farm descriptions that are based on old surveys
For everyday talk in the United States, people usually just say 22acre22 and do not worry about the tiny difference between the survey acre and the international acre. In science and most modern engineering, square meters and hectares are preferred.
Example Conversions
These examples use rounded numbers so they are easier to remember and use.
From acre (US survey) to other units
- 1 acre (US survey) 3d 43,560 square US survey feet
- 1 acre (US survey) 3d about 4,046.87 square meters
- 1 acre (US survey) 3d about 0.4047 hectare
- 1 acre (US survey) 3d about 0.0015625 square mile
From other units to acre (US survey)
- 1 square meter 3d about 0.0002471 acre (US survey)
- 1 hectare 3d about 2.471 acre (US survey)
- 1 square mile 3d 640 acres (US survey)
Worked examples
Example 1: A farm is 5 acres (US survey).
- In square feet: 5 x 43,560 = 217,800 square feet
- In hectares: 5 x 0.4047 3d about 2.02 hectares
Example 2: A field is 10,000 square meters. How many acres (US survey) is that
- 10,000 x 0.0002471 3d about 2.47 acres (US survey)
Related Units
Other units commonly used with or instead of the acre (US survey) include:
- Acre (international) 2d very close in size but based on the international foot
- Square foot 2d a small area unit, often used for houses and rooms
- Square meter 2d basic metric area unit
- Hectare 2d 10,000 square meters, used for farms and forests
- Square mile 2d used for large regions like counties and lakes
- Square rod or square perch 2d old units used in some land records, 160 of these make 1 acre
FAQs
Is an acre (US survey) the same as a regular acre
No. They are almost the same, but not exactly. A regular or international acre is based on the international foot, while the US survey acre is based on the US survey foot. The size difference is extremely small, only important in very precise surveying work.
Why was the acre (US survey) created
It was created to match the US survey foot used in official land surveys in the United States. Surveyors needed fixed rules so that maps, land grants, and property lines would stay consistent over time.
Do I need to care which acre I use
For normal life, no. If you hear that a house sits on 1 acre, you can think of it as either type, since the difference is too small to matter. For legal land records or professional surveying, yes, you should use the exact kind named in the documents.
Which is bigger, the US survey acre or the international acre
The US survey acre is slightly bigger than the international acre. The difference is only a few square centimeters over a whole acre, which is less than the size of a sheet of paper.
Where might I see acre (US survey) written out
You may see it in old US government land records, in technical notes on survey maps, or in engineering documents that must match historic land measurements exactly.
What metric unit is closest in size to an acre (US survey)
The closest simple metric unit is the hectare. One hectare is about 2.471 acres (US survey), so an acre (US survey) is a bit less than half a hectare.