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Cone Calculator (V = ⅓πr²h)

Quick answer

Cone volume, slant height and surface: V = ⅓πr²h, l = √(r²+h²), A = πr(r+l).

  • Example: r = 3, h = 4 ft → V = 37.70 ft³, l = 5 ft.

Figures are estimates from this calculator’s standard formula — adjust the inputs in the tool below for your exact number.

How the Cone Calculator Works

V = ⅓πr²h, l = √(r² + h²), A = πr(r + l)

The cone is one third of its bounding cylinder; slant height comes from Pythagoras and drives the lateral surface. Worked example: r = 3 ft, h = 4 ft → V = ⅓π × 9 × 4 = 37.70 ft³, l = √(9+16) = 5 ft, lateral A = πrl = 47.12 ft², total A = π × 3 × (3+5) = 75.40 ft².

  1. 1

    Enter radius and height

    Perpendicular height h, same units as r.

  2. 2

    Calculate

    Volume, slant, lateral and total area together.

  3. 3

    Convert units if needed

    ft³ ↔ gallons, m³ ↔ liters.

Use Cases

Traffic cones, hoppers and funnels capacity

Ice cream cone and waffle sizing

Roof spires and conical caps material

Snow-cone syrup and batch volumes

Tips

  • 1

    l² = r² + h² links all three cone dimensions

  • 2

    Lateral surface unrolls to a sector of radius l

  • 3

    ⅓ appears because a cone packs three-to-a-cylinder

Common Mistakes

  • Using slant height l as the height h in V = ⅓πr²h

  • Forgetting the ⅓ factor (getting cylinder volume)

  • Radius/diameter mix-ups

  • Adding base twice in total area

FAQs