Area of a Square Calculator
The area of a square is its side squared, A = a²: a square with 5 cm sides has an area of 25 cm². From the diagonal, A = d² ÷ 2.
25 cm²
- Area
- 25 cm²
- Side
- 5 cm
- Perimeter
- 20 cm
- Diagonal
- 7.07107 cm
In other units: 0.0025 m² · 2500 mm² · 2.5 × 10⁻⁹ km² · 2.5 × 10⁻⁷ ha · 0.0269098 ft² · 3.87501 in² · 0.00298998 yd² · 6.17763 × 10⁻⁷ ac · 9.65255 × 10⁻¹⁰ mi²
Step-by-step solution
- A = a²
- A = 5² = 25 cm²
Area of a Square Formula
A = a² = d² ÷ 2
a side length, d diagonal
Worked Example
A square with 5 cm sides:
- A = a²
- A = 5² = 25 cm²
Side: 5 cm · Perimeter: 20 cm · Diagonal: 7.07107 cm
Same area in other units: 0.0025 m² · 2500 mm² · 2.5 × 10⁻⁹ km² · 2.5 × 10⁻⁷ ha · 0.0269098 ft²
Frequently asked questions
How do I find the area of a square from its diagonal?
Square the diagonal and halve it: A = d² ÷ 2. A square with a 10 cm diagonal has an area of 50 cm². This works because d = a√2, so d² = 2a².
How do I find the side of a square from its area?
Take the square root: a = √A. A 64 m² square has 8 m sides.
Is a square also a rectangle?
Yes. A square is a rectangle with four equal sides, so A = l × w gives the same result as A = a².
Sources
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures .
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology .
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
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APA
Scientific Converters. (2026, October 15). Area of a Square Calculator. Retrieved October 25, 2026, from https://scientificconverters.com/calculators/area-of-a-square/
IEEE
Scientific Converters, "Area of a Square Calculator," scientificconverters.com. Accessed: Oct. 25, 2026. [Online]. Available: https://scientificconverters.com/calculators/area-of-a-square/