How big is an acre of land?

If you’ve ever dealt with any type of property, whether it’s vacant land, commercial lots, or a homesite to build your dream house, then you’re familiar with the acre. Square feet and acres are the standard units of measurement we use for real estate in the United States. But have you ever stopped to think what exactly is an acre, where it came from, and what originally determined the size of an acre?

Not only is the origin of the acre interesting, but it can be helpful to understand land history and why we operate the way we do in real estate.

The word “acre” traces back to the Old English term æcer meaning “open field” and was generally used to describe unoccupied country. In English, it was historically spelled “aker” and was related to the Latin word “ager” meaning “field.”

The very first definition of an acre was very interesting. Originally, an acre was the typical area of land that could be plowed by one man, in one day, using a team of oxen and a wooden plow. If you’re thinking… that seems like an inexact science, you’d be right. Here’s the story explaining how you can come up with an acre measurement using that early way of doing things.

It was standard practice to rest the oxen after they plowed ⅛ of a mile (660 feet). A unit of measurement came out of this practice known as a furrow-long, or furlong which measured that exact distance of 660 feet. A farmer would want to plow as much and as far as he could before he had to rest the animals.

The easiest way to accomplish this was to plow as far as he could in a straight line. Turning the plow around wasn’t as easy as it might sound with the oxen team in the heat of the sun. Farmers tended to plow long distances to reduce the number of times they’d have to turn the plow in the opposite direction as well.

Today we define an acre as 43,560 square feet, but the original size of an acre originated in agriculture with quite a bit less precision.

Farmers took pride in being able to plow a straight furrow. With a plowshare around 10 inches wide, your average farmer supposedly could plow a furlong’s length 80 times in a day covering a width of around 66 feet of farmland. 66 feet multiplied by a furlong of 660 feet comes out to 43,560 square feet.

As you can easily see, there are many variables in this equation. The chances of an actual farmer plowing exactly 43,560 square feet every time they stepped on the field is quite small. How old is the farmer and what kind of shape is he in? Are the oxen well-fed and healthy or in bad condition, old, or sick? Is the field topography level with rich soil or is it hilly and rocky? These variations translated into variations in the area a farmer could till, which in turn resulted in variation in the size of an acre.

During his reign in England from 1272 - 1307, Edward I (also known as Edward Longshanks) enacted a statutory value for the area of an acre as 4 rods wide by 40 rods long (one rod equals 16.5 feet). Edward III, Edward VIII, George IV, and then Queen Victoria in 1878 with the Weights and Measures Acts also contributed to creating exact values for the acre.

It's worth notating that although an acre is the same when it comes to size, it's not at all the same when it comes to price. An acre of beachfront land is likely to be worth significantly more than an acre without waterfront. If you're interested in learning more, check out our article discussing the cheapest place to buy land.

In this short video by America’s Heartland, Dan Macon sums up just how big an acre is and how many average bushels of certain crops are produced on an acre.

There are all kinds of units of measurements we could use to measure land area, so why do we use the acre? There are several reasons. The acre is what England was using at the time the United States was being established. Since that’s what we’ve always used and change is hard, we’ve kept using it.

More importantly, the acre makes sense for all property sizes. There are times when square miles is used for large tracts of land, but it wouldn’t be practical to use square miles on small properties. A square mile is the equivalent of 640 acres. It’s much easier to envision half an acre than 1/1,280 of a square mile.

Square feet are often used with small residential lots and certain commercial properties, but when you start getting into larger tracts of land you’re going to be talking thousands and millions of square feet, which isn’t practical either. The acre works for large and small properties alike.

What about surface area? It makes sense to wonder if surface area comes into play in the measurement of acres. What about hilly or mountainous land as opposed to flat, level ground? The answer is surface area doesn’t matter in acreage. Surveyors use basic geometry (geometry literally means earth measurement) to calculate acreage based on a common horizontal topography called plane surveying for almost all types of land.

Even though a parcel may contain a significantly larger surface area than another, the surveyor will act as though they are both flat and they could both end up totaling the same acreage.

Since square footage is used with so many properties, especially land with houses and commercial properties with structures, it’s useful to know how to convert square feet to acres and acres to square feet. The easiest way to do this is to use proportions or simple multiplication and division.

To convert square feet to acres, simply divide the square footage by 43,560.

Here's a simple example.

59,670 square feet is how many acres?
59,670 / 43,560 = 1.37
59,670 square feet is the same as 1.37 acres

To convert acres to square feet, since 1 acre = 43,560 square feet, multiply the acreage by 43,560.

Take a look at this scenario.

0.85 acres is how many square feet?
0.85 x 43,560 = 37,026
0.85 acres is the same as 37,026 square feet.

Take a look at these conversions. Some you may recognize and some you may not.

The acre is interesting in that it can literally be any shape, as long as the total area of the shape is 43,560 square feet. Acreage comes into play in all sorts of outdoor endeavors whether you're buying and selling property, hunting, or landscaping.

Most people deal with real estate in one way or another throughout their lives. When it comes to land, acres are especially important since the price per acre you’re going to pay is largely dependent on its size. Hopefully knowing a little background and history will make dealing with acreage a little more interesting as you explore land for sale.