Sonotube Concrete Calculator: Bags, Volume and Piers

Sonotube Concrete Calculator

Estimate concrete volume, whole bags, ready-mix quantity and form tubes for round piers or columns.

Units

Number of tubes

Inside diameter (in)Use the actual inside diameter when available.

Concrete fill length (ft)

Base below tube

Base diameter (in)

Base depth (in)

Add tubes of another size

Add a second tube group

Number of larger/smaller tubes

Inside diameter (in)

Concrete fill length (ft)

Base below tube

Base diameter (in)

Base depth (in)

Allowance, bags, ready mix and tube stock

Extra concrete (%)

Mixed yield per bag (ft³)Copy the yield from the exact product label.

Price per bag

Ready-mix price per yd³

Available tube length (ft)Identical pieces are cut from this stock length.

Concrete to plan—

—Volume including allowance

—Whole bags

—Bag material cost

—Ready-mix volume and material cost

—Separate base volume

—Bag yield left over

—Total form-tube length

—Stock form tubes

—Average concrete per pier

Tube-group breakdown

Group	Quantity	Tube concrete	Base concrete	Stock tubes

Formulas

Tube volume = π × diameter² ÷ 4 × fill length × quantity. A straight base is another cylinder. A tapered or bell base is treated as a conical frustum: V = πh(D² + Dd + d²) ÷ 12, where D is the bottom diameter and d is the tube diameter.

Worked example

Six 12 in diameter tubes filled 4 ft high require about 18.850 ft³ before allowance. With 10% added, that is about 20.735 ft³ or 0.768 yd³. At 0.60 ft³ of mixed yield per bag, order 35 whole bags. A 12 ft stock tube produces three 4 ft forms, so two stock tubes cover six identical piers.

Why this differs from a general concrete calculator

This tool combines multiple tube sizes, optional enlarged bases, whole bags, ready-mix volume and a simple stock-tube cutting count. Use the general Concrete Calculator for slabs, rectangular footings and other shapes.

Limits

Sonotube is a brand name commonly used for round fiber forms. Use the actual inside diameter and product instructions for the form you buy.
The base is modeled directly below the tube and does not overlap its cylindrical fill. Excavation irregularity, loss, consolidation and overfill require an appropriate allowance.
Stock-tube counts assume identical straight cuts within each group. When a form is longer than the entered stock length, the result flags that a longer or manufacturer-approved joined form is needed.
Bag yield and ready-mix price are user inputs. The result excludes short-load charges, delivery, pumping, reinforcement, excavation, brackets, labor and tax.
This is a quantity estimate, not a structural footing or pier design. Diameter, depth, base geometry, reinforcement, frost depth, soil capacity and connections require project-specific design and local code compliance.