Calculate the area of a circle, square or triangle online. A simple and accurate calculator with formulas.
Calculate the area of a circle, square or triangle online. A simple and accurate calculator with formulas.
Online calculator for calculating the area of basic geometric shapes: circle, square and triangle. Easy to use tool with automatic calculation using formulas. Suitable for students, engineers and anyone who needs to quickly calculate the area of a figure.
Let's look at practical examples of calculating the area of various geometric shapes:
Circle with radius 5 cm
Area: 78.5 cm²
Square with side 8 m
Area: 64 m²
Triangle with base 6 cm and height 4 cm
Area: 12 cm²
Circle with radius 10 m
Area: 314 m²
Square with side 15 cm
Area: 225 cm²
Triangle with base 12 m and height 8 m
Area: 48 m²
The area of a circle is calculated by the formula S = π × r², where r is the radius. The area of a square is calculated as S = a², where a is the length of the side. The area of a triangle is calculated by the formula S = ½ × a × h, where a is the base, h is the height.
Accurate calculations using mathematical constants
Results are calculated automatically as you enter data
Using standard mathematical geometry formulas
Responsive design for easy use on all devices
Fast and accurate area calculations, support for basic geometric shapes, clear interface, automatic application of mathematical formulas, results accurate to 2 decimal places.
Make sure all values are positive. For a circle, enter the radius, for a square - the length of the side, for a triangle - the base and height. The result is displayed in square units.
The area of a circle is calculated by the formula S = π × r², where π ≈ 3.14, r is the radius of the circle. For example, for a circle with a radius of 5 cm: S = 3.14 × 5² = 78.5 cm².
The area of a square is calculated by the formula S = a², where a is the length of the side. For example, a square with a side of 8 m has an area S = 8² = 64 m².
The area of a triangle is calculated by the formula S = ½ × a × h, where a is the base, h is the height. For example, a triangle with a base of 6 cm and a height of 4 cm: S = ½ × 6 × 4 = 12 cm².
The calculator works with any length units (cm, m, inches, feet). The area result will be in the corresponding square units (cm², m², in², ft²).
For a rectangle, use the formula for the area of a square, but keep in mind that the sides may be different. Area of a rectangle: S = a × b, where a and b are the lengths of the sides.
For irregularly shaped rooms, divide it into simple shapes (rectangles, triangles), calculate the area of each part and add up the results.
The area of the ellipse is calculated by the formula S = π × a × b, where a and b are the semi-axes of the ellipse. Our calculator doesn't yet support ellipse, but you can use the formula.
The area of a trapezoid is calculated by the formula S = ½ × (a + b) × h, where a and b are the bases of the trapezoid, h is the height. Our calculator does not yet support trapezoid.
The area of a parallelogram is calculated by the formula S = a × h, where a is the base, h is the height. Use the triangle calculator and multiply the result by 2.
The area of a rhombus can be calculated in two ways: S = a × h (as a parallelogram) or S = ½ × d₁ × d₂ (via diagonals), where d₁ and d₂ are the diagonals of the rhombus.
For a regular polygon, the area is calculated by the formula S = ½ × P × a, where P is the perimeter, a is the apothem. For irregular polygons, break into triangles.
The area of a circle sector is calculated by the formula S = (α/360°) × π × r², where α is the central angle in degrees, r is the radius of the circle.
The area of a circle segment is calculated as the difference between the area of the sector and the area of the triangle formed by the radii and the chord.
The area of the ring is calculated as the difference between the areas of two circles: S = π × (R² - r²), where R is the outer radius, r is the inner radius.
The surface area of the cylinder consists of two circles and a rectangle: S = 2πr² + 2πrh, where r is the radius of the base, h is the height of the cylinder.
The surface area of a sphere is calculated by the formula S = 4πr², where r is the radius of the sphere. This is 4 times the area of a circle of the same radius.
The surface area of the cone is calculated by the formula S = πr² + πrl, where r is the radius of the base, l is the generatrix of the cone.
The surface area of the pyramid includes the area of the base and the area of the side faces. For a regular pyramid: S = S₀ + ½Pl, where S₀ is the area of the base, P is the perimeter of the base, l is the apothem.
The surface area of a prism is calculated as the sum of the areas of the two bases and the area of the side surface: S = 2S₀ + Pl, where S₀ is the area of the base, P is the perimeter of the base, l is the height of the prism.
The surface area of a cube is calculated by the formula S = 6a², where a is the length of the cube edge. This is the sum of the areas of all six faces.
The surface area of a parallelepiped is calculated by the formula S = 2(ab + bc + ac), where a, b, c are the lengths of the edges of the parallelepiped.
The surface area of a tetrahedron is calculated as the sum of the areas of the four triangular faces. For a regular tetrahedron: S = √3 × a², where a is the edge length.
The surface area of the octahedron is calculated as the sum of the areas of the eight triangular faces. For a regular octahedron: S = 2√3 × a², where a is the edge length.
The surface area of the icosahedron is calculated as the sum of the areas of twenty triangular faces. For a regular icosahedron: S = 5√3 × a², where a is the edge length.
The surface area of a dodecahedron is calculated as the sum of the areas of twelve pentagonal faces. For a regular dodecahedron: S = 3√(25+10√5) × a², where a is the edge length.
The surface area of the torus is calculated by the formula S = 4π²Rr, where R is the distance from the center of the torus to the center of the pipe, r is the radius of the pipe.
The surface area of the ellipsoid is calculated using a complex formula depending on the semi-axes a, b, c. For a spheroid (a = b ≠ c) the formula is simplified.
The surface area of a hyperboloid is calculated using integral calculus and depends on the parameters of the hyperboloid.
The surface area of a paraboloid is calculated using integral calculus and depends on the parameters of the paraboloid.
The area of a cylindrical surface is calculated by the formula S = 2πrh, where r is the radius of the base, h is the height of the cylinder.