What is a cone?
A cone is a three-dimensional solid with a circular base and one apex. This calculator is designed for a right circular cone, where the apex is directly above the center of the circular base. The two main dimensions are the base radius and the perpendicular height.
The calculator can be used for classroom mathematics, engineering estimates, fabrication checks, construction calculations, packaging, landscaping, and many other situations where cone dimensions need to be converted into measurable areas or volume.
How to calculate the volume of a cone
The volume of a cone is one-third of the volume of a cylinder that has the same base radius and height. Use the formula below:
For example, a cone with a radius of 3 m and a height of 4 m has a volume of approximately 37.699 m³. The same calculation works in feet, inches, centimeters, or millimeters when all dimensions use the same unit.
How to find slant height
The slant height is the straight-line distance from the apex to a point on the circular edge of the base. For a right circular cone, it can be found using the Pythagorean theorem:
The calculator uses this value to determine the curved surface area and total surface area of the cone.
Cone surface area formulas
Base area
A = πr²
Curved surface area
A = πrl
Total surface area
A = πr(r + l)
Cone calculator example
The following example uses a cone with a radius of 3 m and a perpendicular height of 4 m. The slant height is 5 m, allowing the remaining measurements to be calculated from the standard cone formulas.
| Measurement | Formula / Value | Result |
|---|---|---|
| Radius | Given | 3 m |
| Diameter | d = 2r | 6 m |
| Height | Given | 4 m |
| Slant height | l = √(r² + h²) | 5 m |
| Base area | A = πr² | 28.274 m² |
| Curved surface area | A = πrl | 47.124 m² |
| Total surface area | A = πr(r + l) | 75.398 m² |
| Volume | V = ⅓πr²h | 37.699 m³ |
Common uses of cone calculations
Cone calculations are useful when estimating material quantities, hopper capacity, roof or funnel dimensions, pile volumes, packaging sizes, and geometric quantities in design or education. For real construction work, verify the final dimensions and quantities against project drawings, specifications, and applicable standards.
Frequently asked questions
What is the difference between radius and diameter?
The radius extends from the center of the circular base to its edge. The diameter crosses the entire circle and is twice the radius: d = 2r.
Can I use feet, inches, centimeters, or millimeters?
Yes. Select the required unit from the measurement menu. The calculator keeps the radius and height in the selected unit and displays length, area, and volume results using that same unit.
What is the slant height of a cone?
The slant height is the straight-line distance from the apex to a point on the circular edge of the base. For a right circular cone, use l = √(r² + h²).
Does this calculator work for an oblique cone?
No. This calculator is intended for a right circular cone, where the apex is directly above the center of the circular base.
Why is cone volume measured in cubic units?
Volume measures three-dimensional space. Therefore, meters produce cubic meters (m³), feet produce cubic feet (ft³), and other units are similarly cubed.
How is total surface area calculated?
Total surface area combines the circular base and curved surface: A = πr² + πrl, which can also be written as A = πr(r + l).