The calculator calculates the total surface area of the cylinder. It is possible to specify the number of outer and inner planes. Indicate the presence of threads on each plane. Just specify the planes in order. Only the height of the cylinder and the diameter of the cylinder are needed. Grooves are calculated automatically if one of the diameters is smaller than the neighboring ones. If the sum of the heights of the outer planes is less than the sum of the heights of the inner holes, then the hole is considered not through. The areas are displayed separately along the planes, this is the double area of the base (end), the area of the entire outer side surface in total (External), the area of the entire inner surface in total (Internal). At the point of the groove, only the sum of the end planes obtained during deepening is added. When you click the "Calculate the total plane" button, the results are summarized and displayed separately. The output is implemented in millimeters and decimeters square. Rounded to three decimal places. The number of outer planes is limited to 15. Suggestions for improvement are accepted. Good luck to everyone!