DIY Cost Tools
Cone Volume Calculator
MATH CALCULATOR
Calculate a right circular cone’s volume, slant height, and total surface area.
Use consistent units. All fields are required; absolute input values must not exceed one trillion. Surface-area and slant-height formulas assume a right circular cone.
How to use this calculator
Replace the example inputs with your measurements, then select Calculate. Results use the units shown beside each field. Keep extra precision in the inputs and round only when recording the final answer.
Formula and explanation
V = πr²h ÷ 3; slant height l = √(r² + h²); total area = πr(r + l)
Height is measured perpendicular to the circular base. The slant height runs along the side from the rim to the apex.
Worked example
With Base radius (units) = 3, Perpendicular height (units) = 4, the results are Volume (cubic units): 37.699112; Slant height (units): 5; Total surface area (square units): 75.398224.
Important limitations
Surface-area and slant-height formulas assume a right circular cone. These results do not include wall thickness, seams, or material waste.
Results are estimates based on the entered values. Numeric precision does not eliminate measurement uncertainty.
Frequently asked questions
Which height should I enter?
Use the perpendicular height from the base center to the apex, not the slanted side length.
Does total area include the base?
Yes. It includes both the curved side and the circular base.
What happens if I leave a field blank?
The tool clears the previous result and asks for valid inputs, so an old answer is not mistaken for a new calculation.
Review notes
Reviewed October 1, 2026. Default calculations were checked independently against the displayed equations. The script validates blank, nonfinite, out-of-range, and formula-specific invalid inputs. Calculations run locally in your browser.