Twin Calculators (Twofold Calculators), which combines two calculators into one, and the calculation result can be copied and pasted between the two calculators with one click.

Perimeter Calculator supports perimeter calculations for common geometric figures such as Circular, Sector, Ellipse, Triangle, Square, Rectangle, and Parallelogram. You can use different formulas and methods to calculate the perimeter of these geometric figures depending on the shape and the given information.

Area Calculator supports area calculations for common geometric figures such as Circular, Sector, Ring, Ellipse, Triangle, Square, Rectangle, Parallelogram and Trapezoid.

Surface Area Calculator supports surface area calculations for common geometric figures such as Sphere, Spherical Sector, Segment, Cylinder, Hollow Cylinder(Pipe), Oblique Straight Cylinder, Cone, Circular Truncated Cone, Ellipsoid, Triangle Prism, Pyramid, Cube, Cuboid, Torus and Sphere Belt.