Find the concrete you need to top up a tube.
⚙️Calculation Parameters
📊Calculated Output
How Sonotube Top-Up Calculator Works?
To top up a tube, the Sonotube Top-Up Calculator finds the volume between the current concrete level and the target finish height. The process takes 4 steps.
Enter the tube diameter
Type the inside diameter of the form.
Measure the current level
Measure from the tube top down to the concrete, or from the bottom up.
Enter the target height
Type the finish height, such as the top of the form or a mark for a post base.
Read the top-up volume
The calculator returns cubic feet (ft³), liters (L) and the count of small bags.
Sonotube Top-Up Calculator Formula
The Sonotube Top-Up Calculator works on the height gap only.
Gap
Δh = h_target − h_currentBoth measured from the same reference.
Top-up volume
V = π × (D ÷ 24)² × (Δh ÷ 12)Δh in inches gives ft³.
From the top
Δh = drop below rim − target dropUse a tape from the tube rim down.
Worked example: 10 in tube, concrete 5 in below the rim, target is the rim
- Δh = 5 in
- V = 0.5454 × (5 ÷ 12) = 0.227 ft³ (6.4 L)
- One 50 lb (23 kg) bag yields 0.375 ft³, so 1 bag finishes the tube
Sonotube Top-Up Calculator Conversion Table
The top-up conversion table lists the concrete needed to raise 4 tube sizes by 2 in, 4 in and 6 in (5 cm, 10 cm and 15 cm).
| Tube | ft³ per inch | ft³ for 2 in | ft³ for 4 in | ft³ for 6 in | 50 lb bags for 6 in |
|---|---|---|---|---|---|
| 8 in | 0.0291 | 0.058 | 0.116 | 0.175 | 1 |
| 10 in | 0.0455 | 0.091 | 0.182 | 0.273 | 1 |
| 12 in | 0.0654 | 0.131 | 0.262 | 0.393 | 2 |
| 16 in | 0.1164 | 0.233 | 0.465 | 0.698 | 2 |
Top-ups bond best on fresh concrete. On hardened concrete, clean the surface and use a bonding agent.
What is Sonotube Top-Up Calculator?
A Sonotube Top-Up Calculator is a small-volume tool that finds the concrete needed to raise the level in a partly filled tube to a target height.
Concrete settles a little after rodding, a batch runs short, or a crew stops below the rim. Top-ups are small: a 10 in tube needs 0.045 ft³ per inch of height. The calculator turns that into bags or liters, so a crew mixes only the amount needed.
The tool measures gaps from the rim down, which matches how a crew reads a tape on site.
What are the uses of Sonotube Top-Up Calculator?
There are 4 main uses of the Sonotube Top-Up Calculator.
Short batches
Crews finish a tube when the last batch falls short.
Settlement correction
Builders fill the dip that forms after rodding and vibration.
Post base height
Installers raise concrete to a set height for anchor hardware.
Repairs
Owners raise an existing low pier to new grade.
🔗Related Sonotube Calculators
View all 106 subtools →Sonotube Partial Fill Calculator
Find the concrete for a tube you fill part way.
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.
Available Concrete Fill Height Calculator
See how high your concrete will reach.