Square Kilometer — Definition, Formula & Examples

A square kilometer is a unit of area equal to a square that is 1 kilometer long on each side. It is used to measure large areas like cities, lakes, and countries.

A square kilometer (symbol: km²) is a metric unit of area defined as the area of a square with sides each measuring exactly 1 kilometer, equivalent to $1{,}000{,}000$ square meters.

Key Formula

1 \text{ km}^2 = 1{,}000{,}000 \text{ m}^2

Where:

$\text{km}^2$ = square kilometers, the larger unit of area
$\text{m}^2$ = square meters, the smaller unit of area

How It Works

To find an area in square kilometers, measure the length and width in kilometers and multiply them together. One square kilometer equals

1{,}000{,}000

square meters because

1{,}000 \times 1{,}000 = 1{,}000{,}000

. Square kilometers are practical for describing regions too large for square meters, such as national parks, islands, or entire states.

Worked Example

Problem: A rectangular park is 3 km long and 2 km wide. What is its area in square kilometers?

Step 1: Write the area formula for a rectangle.

A = \text{length} \times \text{width}

Step 2: Multiply the length and width.

A = 3 \text{ km} \times 2 \text{ km} = 6 \text{ km}^2

Answer: The park has an area of

6 \text{ km}^2

Why It Matters

Square kilometers appear in geography, science, and news reports whenever large land or water areas are described. Understanding this unit helps you compare the sizes of countries, oceans, and forests using real data.

Common Mistakes

Mistake: Thinking 1 km² equals 1,000 m² instead of 1,000,000 m².

Correction: Both dimensions are converted: 1 km = 1,000 m, so 1 km² = 1,000 × 1,000 = 1,000,000 m². You must square the conversion factor, not just multiply it once.