What is square foot?

A square foot is a unit of area in imperial and US customary systems equal to 144 square inches. It is commonly used in the United States for real estate listings, floor plans, and building layouts.

Real-world uses

Square feet are the primary unit for real estate in the United States, Canada, and parts of South Asia. Office space, apartment listings, and retail floor plans are quoted in sq ft. Flooring, tiles, and paint coverage are sold per square foot in these markets.

History

The square foot derives directly from the foot, which has been used since ancient times. It became the de facto real estate standard in the United States and remains deeply entrenched in American property markets despite the global shift toward metric units.

Common mistakes

Forgetting that square footage is an area measure, not a length. A 1,000 sq ft apartment is not 1,000 feet long. Also, nominal tile sizes often include grout spacing, so actual coverage per tile is slightly less than the stated size.

What is square kilometre?

A square kilometre is a metric unit of area equal to one million square metres. It is used for measuring large geographic areas such as countries, forests, lakes, and urban zones.

Real-world uses

Square kilometres are used for country areas, city boundaries, national park sizes, and deforestation tracking. Geographic and environmental data, including satellite imagery resolution, reference areas in km². Singapore is about 733 km², for scale.

History

The square kilometre became the standard large-area unit with global metrication, replacing traditional units like the square league. It is the preferred unit for geographic and political area comparisons in international statistics and the United Nations system.

Common mistakes

Thinking 1 km² = 1,000 m². It is actually 1,000,000 m² (1 km × 1 km). Also, confusing square kilometres with kilometres squared in conversation, though mathematically they mean the same thing.

When is this conversion used?

Converting between square foot and square kilometre is common when working across metric and imperial systems, such as international trade, travel between countries with different measurement standards, or following instructions from a different region.

Worked examples

1 square foot = 9.290304e-08 square kilometre

1 square kilometre = 1,000,000 square metre

How to convert square foot to square kilometre

To convert square foot to square kilometre, multiply the value by 9.290304e-08.

To convert square kilometre back to square foot, multiply by 10,763,910.41670972.

Measurement standards

The square metre is the SI derived unit of area. The hectare (10,000 m²) is accepted for use with the SI by the BIPM, particularly for land measurement, though it is not an SI unit itself.

Did you know?

Vatican City, the world's smallest independent state, covers just 0.44 km² (about 109 acres) — smaller than many golf courses. By contrast, Russia spans over 17.1 million km², nearly 39 million times larger.

Quick reference: square foot to square kilometre

Common values

Available Area units

• square metre conversions
• square kilometre conversions
• square foot conversions
• square mile conversions
• acre conversions
• hectare conversions
• square centimetre conversions
• square inch conversions
• square yard conversions
• are conversions

More square foot conversions

• Convert square foot to square metre
• Convert square foot to square kilometre
• Convert square foot to square mile
• Convert square foot to acre
• Convert square foot to hectare
• Convert square foot to square centimetre
• Convert square foot to square inch
• Convert square foot to square yard
• Convert square foot to are