Get the volume from the radius and height.
⚙️Calculation Parameters
📊Calculated Output
How Radius-Based Sonotube Calculator Works?
To calculate volume from a radius, the Radius-Based Sonotube Calculator skips the diameter step and squares the radius directly. The process takes 4 steps.
Measure center to wall
Measure from the center of the form or hole to the inside wall. That distance is the radius (r).
Enter the radius and height
Type r and the pour height (h) in inches or centimeters (cm).
Square the radius
The calculator multiplies r by itself and by pi (π) to get the circle area.
Multiply by height
The circle area times h gives the fill in cubic feet (ft³), cubic yards (yd³) and liters (L).
Radius-Based Sonotube Calculator Formula
The Radius-Based Sonotube Calculator uses the textbook cylinder formula with no diameter conversion.
Cylinder volume
V = π × r² × hr and h in the same unit give a cubic result in that unit.
Radius in inches to ft³
V (ft³) = π × (r ÷ 12)² × (h ÷ 12)Divide inch values by 12 to get feet.
Radius from diameter
r = D ÷ 2Use when only the tube label is known.
Worked example: r = 6 in, h = 42 in
- r = 6 ÷ 12 = 0.5 ft and h = 42 ÷ 12 = 3.5 ft
- V = 3.1416 × 0.25 × 3.5 = 2.749 ft³
- 2.749 ft³ = 0.1018 yd³ = 77.8 L
Radius-Based Sonotube Calculator Conversion Table
The radius conversion table maps 7 radius values to their tube diameter, circle area and fill volume.
| Radius | Equal diameter | Area (ft²) | ft³ per 12 in | ft³ at 48 in |
|---|---|---|---|---|
| 3 in (7.62 cm) | 6 in | 0.1963 | 0.196 | 0.79 |
| 4 in (10.16 cm) | 8 in | 0.3491 | 0.349 | 1.40 |
| 5 in (12.70 cm) | 10 in | 0.5454 | 0.545 | 2.18 |
| 6 in (15.24 cm) | 12 in | 0.7854 | 0.785 | 3.14 |
| 8 in (20.32 cm) | 16 in | 1.3963 | 1.396 | 5.59 |
| 9 in (22.86 cm) | 18 in | 1.7671 | 1.767 | 7.07 |
| 12 in (30.48 cm) | 24 in | 3.1416 | 3.142 | 12.57 |
Doubling the radius multiplies the volume by 4, since the radius term is squared.
What is Radius-Based Sonotube Calculator?
A Radius-Based Sonotube Calculator is a cylinder volume tool that takes the radius of a round form instead of its diameter.
Field crews often measure radius when a hole has no form yet, when a form is too wide to span with a tape, or when a site plan lists a radius from the pier center. The calculator uses that number directly, which removes the halving step and the error of squaring a diameter by mistake.
Squaring the diameter in place of the radius gives a volume 4 times too large. The radius input prevents that error.
What are the uses of Radius-Based Sonotube Calculator?
There are 4 main uses of the Radius-Based Sonotube Calculator.
Hole checks before forming
Crews measure from a center stake to the hole wall and get the volume of the open hole.
Large column forms
Contractors measure half the span of 30 in to 48 in forms.
Geometry drawings
Designers read radius dimensions from CAD (computer-aided design) plans.
Classroom math
Students check textbook cylinder problems written with r.
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