Square Kilometers and Acres Converter

Acres (an imperial unit) and square kilometers (a metric unit) are two units of area that are usually used to describe larger landmasses and areas, due to their larger default sizes. 

This converter will allow you to convert between them.

Start by choosing between the British or the American spelling, which will affect how the word kilometer is spelled (it is spelled ‘kilometre’ in the British way).

You choose your input unit in the ‘CONVERT FROM’ and your output unit in the ‘CONVERT TO’ section. The choice is between the already mentioned square kilometers ($km^2$) and acres (ac). Aside from choosing each option at a time, you can also go with the default selection, or just swap the units by clicking on the icon of the two arrows in opposite directions. 

When the input and output units are set to your liking, you can proceed to the ‘VALUE TO CONVERT’ part, where you write in your input as a decimal number.

Choose the number of decimal places you want your result rounded toward and click on ‘CONVERT’.

You will receive your result in the output unit of your choosing, alongside a conversion rate between the units. Feel free to use the ‘COPY’ icon next to your result for easy copying and pasting.

Converting Square Kilometers and Acres Manually

The relationship between acres and square kilometers can be summarized by the conversion rates between them.

• 1 acre is equivalent to 0.00405 $km^2$, meaning that the conversion rate of acres to $km^2$ is 1:0.00405 or 100,000:405, which simplifies to 20,000:81. 
• 1 $km^2$ is equivalent to 247.1 acres, making the conversion rate of $km^2$ to acres equal to 1:247.1, or 10:2,471.

These conversion rates lead to 2 formulae which will help us with manual conversions.

Choosing the right formula is a matter of observing which unit is your input and which one is your output. You should always aim at using the formula, where the output you are trying to calculate is the subject of the formula (in the case of our formulae, the subject is the variable on the left side which stands alone).

EXAMPLE 1: A developer is planning to transform an area of 1,467 acres into an industrial zone. How many $km^2$ will this industrial zone have? Round your result to two decimal places.

The first formula works best for this problem, as we can substitute acres into it while getting square kilometers as the output and also the subject of the formula. We write the formula and then substitute 1,467 instead of acres.

EXAMPLE 2: A country has an area of 48,740 $km^2$, what is the equivalent area of this country in acres?

We will be using the second formula, as our input is in $km^2$, while our output is in acres. We substitute 48,740 instead of $km^2$ and get the following solution.

What Is an Acre?

An acre is a customary unit of area that is part of the imperial system of measurements.

The history of the acre spans all the way to medieval times when an acre was loosely defined as the area of land that can be plowed by a person with 8 oxen in a day. 

It is obvious that such a definition is not very accurate and the unit itself has undergone many redefinitions before it was accurately established.

The most recent definition that did not tie the unit in with the metric system came from the USA as the area of one chain by one furlong, both archaic units of length that are rarely used nowadays. This defined the area of an acre as 1/640 of a square mile.

Despite being an imperial unit, the usage of acre actually spans beyond countries that use the imperial system, due to its convenient size when describing larger areas.

Areas of Significance

In order to gain a better insight into the comparison between the square kilometer and an acre, we will provide a few examples of nations and countries of geographical significance, and their areas in both units rounded to the nearest tenth of a $km^2$ or acre.

References:

https://en.wikipedia.org/wiki/Acre