Hollow cylinders appear as precast pipe sections, manholes, well rings and architectural columns with a void. The concrete is the ring between the outer and inner diameters; for a solid column set the inner diameter to zero.
How to use the Concrete Estimator – Tube
- Outer diameter
- Inner diameter
- Height
- Quantity
- Waste
- Premix bag size
- Price per bag
- Every result field is editable: type into Total concrete and Height plus every other field update to match.
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter the outer diameter, inner diameter, height, number of tubes, waste, bag size and prices.
Premixed bag yields
| Bag | Yield | Bags per yd³ |
|---|---|---|
| 40 lb | 0.30 ft³ | 90 |
| 50 lb | 0.375 ft³ | 72 |
| 60 lb | 0.45 ft³ | 60 |
| 80 lb | 0.60 ft³ | 45 |
| 25 kg | ≈ 0.0117 m³ | ≈ 85 per m³ |
Tips for an accurate estimate
- Measure the formwork, not the drawing – forms bulge and subgrades are rarely perfectly flat, so add 5–10%.
- Below about 1 cubic yard, premixed bags are usually cheaper; above that, ready-mix saves time and gives a more consistent pour.
- Order ready-mix in quarter- or half-yard steps and ask about short-load fees for small deliveries.
- Keep fresh concrete damp for at least a week – curing matters as much as the mix for final strength.
Common mistakes to avoid
- Running short mid-pour, which leaves a weak cold joint.
- Adding extra water on site to make concrete easier to place – it lowers strength and increases cracking.
- Ignoring the volume of rebar, posts or pipes in the pour, or the gravel base under it.
Inputs explained
| Field | What to enter |
|---|---|
| Outer diameter | Units: in, cm, mm, ft, m |
| Inner diameter | Units: in, cm, mm, ft, m |
| Height | Units: ft, m, in, yd, cm |
| Quantity | A number |
| Waste | In % |
| Premix bag size | Choose one: 40 lb bag (0.30 ft³), 50 lb bag (0.375 ft³), 60 lb bag (0.45 ft³), 80 lb bag (0.60 ft³) … |
| Price per bag | Units: /piece |
What each result means
- Volume of one tube = pi÷4×([Outer diameter]^2 – [Inner diameter]^2)×[Height]
- Total concrete = [Volume of one tube]×[Quantity]×(1 + [Waste]÷100)
- Weight = [Total concrete]×2400
- Premix bags = ceil([Total concrete]÷[Premix bag size])
- Cost = [Premix bags]×[Price per bag]
Formula
V = π/4 × (OD² − ID²) × H × quantity × (1 + waste)Worked example
Inputs — Outer diameter: 24 in; Inner diameter: 18 in; Height: 4 ft; Quantity: 2; Waste: 7 %; Premix bag size: 80 lb bag (0.60 ft³); Price per bag: $6.5 /piece.
Results — Volume of one tube = 5.498 ft³; Total concrete = 0.436 yd³; Weight = 1,763 lb; Premix bags = 20; Cost = $130.00.
Frequently asked questions
What is the volume of a concrete ring?
π/4 × (outer diameter² − inner diameter²) × height.
What wall thickness should a tube have?
Precast pipes and rings typically have walls of 2–6 in depending on diameter and load.
What formula does the Concrete Estimator – Tube use?
V = π/4 × (OD² − ID²) × H × quantity × (1 + waste).