Find the concrete for a tube you fill part way.
⚙️Calculation Parameters
📊Calculated Output
How Sonotube Partial Fill Calculator Works?
To calculate a partial fill, the Sonotube Partial Fill Calculator multiplies the circle area of the tube by the fill height instead of the full tube length. The process takes 4 steps.
Enter the tube diameter
Type the inside diameter in inches (in) or centimeters (cm).
Enter the tube length
Type the full form length for reference.
Enter the fill height
Type how high the concrete rises, measured from the bottom. A form set on a footing or a standoff often fills short of the top.
Read partial volume
The calculator returns the fill in cubic feet (ft³), liters (L) and as a percent of the full tube.
Sonotube Partial Fill Calculator Formula
The Sonotube Partial Fill Calculator uses fill height, not form length.
Partial volume
V_p = π × (D ÷ 24)² × (h_fill ÷ 12)h_fill is the concrete height in inches.
Percent of tube
P = h_fill ÷ L × 100%L is the full form length.
Unfilled volume
V_empty = π × (D ÷ 24)² × ((L − h_fill) ÷ 12)Space left above the concrete.
Worked example: 12 in tube, 48 in long, filled to 30 in
- V_p = 0.7854 × (30 ÷ 12) = 1.963 ft³ (55.6 L)
- P = 30 ÷ 48 = 62.5%
- V_empty = 0.7854 × 1.5 = 1.178 ft³
Sonotube Partial Fill Calculator Conversion Table
The partial fill conversion table lists volumes at 25%, 50% and 75% fill for 4 tube sizes, 48 in (122 cm) long.
| Tube | Full ft³ | 25% (12 in) | 50% (24 in) | 75% (36 in) | ft³ per inch |
|---|---|---|---|---|---|
| 10 in × 48 in | 2.18 | 0.55 | 1.09 | 1.64 | 0.0455 |
| 12 in × 48 in | 3.14 | 0.79 | 1.57 | 2.36 | 0.0654 |
| 16 in × 48 in | 5.59 | 1.40 | 2.79 | 4.19 | 0.1164 |
| 18 in × 48 in | 7.07 | 1.77 | 3.53 | 5.30 | 0.1473 |
The ft³-per-inch column converts any fill height: multiply it by the inches of fill.
What is Sonotube Partial Fill Calculator?
A Sonotube Partial Fill Calculator is a concrete calculator that finds the volume in a round form filled to a set height below the top.
Forms are not always filled to the rim. Builders cut long tubes and leave extra above the pour line, stand a tube on a precast footing, or pour in 2 lifts on 2 days. The calculator measures the actual fill height and ignores the empty top.
The ft³ per inch value doubles as a field check: a 12 in tube rises 1 in for every 0.0654 ft³ (1.85 L) poured.
What are the uses of Sonotube Partial Fill Calculator?
There are 4 main uses of the Sonotube Partial Fill Calculator.
Two-lift pours
Crews size the first lift on day 1 and the second lift on day 2.
Standoff elevations
Builders stop concrete at a marked line below an uncut tube top.
Footing-mounted forms
Installers fill tubes set on precast or plastic footings.
Batch tracking
Mixer operators predict the rise from one batch.
🔗Related Sonotube Calculators
View all 106 subtools →Sonotube Remaining Fill Calculator
See how much is left after part of the pour.
Sonotube Fill Percentage Calculator
See what share of the tube is full.
Sonotube Top-Up Calculator
Find the concrete you need to top up a tube.
Available Concrete Fill Height Calculator
See how high your concrete will reach.