| Section | Inputs | Volume (m³) |
|---|---|---|
| Cylinder | Ø 3.0 × H 10.0 | 70.686 |
| Hopper (frustum) | Ø 3.0 to Ø 0.6 × H 3.0 | 8.765 |
| Roof (cone) | Ø 3.0 × H 1.0 | 2.356 |
| Gross total | Per silo | 81.807 |
| Usable storage | Fill 90%, allowance 2% | 72.154 |
| Mass capacity | Density 1450 kg/m³ | 104.62 t |
Cylinder
Gross cylinder volume:
Where r = diameter ÷ 2, and h is vertical height.
Cone
Used for hopper or conical roof:
This assumes a right circular cone.
Frustum (truncated cone)
Common for hopper transitions:
d₁ is top diameter, d₂ is bottom diameter.
Dome (spherical cap)
If roof is a dome and you enter cap height:
a is base radius (diameter ÷ 2), h is cap height.
Usable storage and mass
Bulk density is optional and depends on material (cement, fly ash, grains, etc.).
- Select your unit system and number of silos.
- Enter cylinder diameter and height. These are required.
- Enable the hopper section if your silo has a cone or transition.
- Enable the roof section if you want to include top volume.
- Set fill level and allowance for safe operating capacity.
- Optionally add bulk density to estimate stored material mass.
Silo volume impacts procurement and schedule
Volume drives ordering, haulage cycles, and plant uptime. A 1 m³ error can mean roughly 1.4–1.6 tonnes of cement or fly ash, depending on bulk density. Use the calculator to size storage against daily consumption, delivery lead time, and buffer stock targets. It also helps compare “taller vs wider” layouts when footprint is limited. Document assumptions in submittals to reduce on-site rework later.
Shapes modeled in this calculator
Most construction silos combine a cylindrical shell with a conical hopper and a roof. This calculator sums each enabled segment: cylinder volume (πr²h) plus cone volume (⅓πr²h). Optional roof volume can be treated as a cone based on your input. This segmented method matches steel and precast silos used for cement, lime, and mineral fillers.
From volume to mass capacity
Site teams usually speak in tonnes, not cubic meters. Enter the material bulk density to convert storage volume to mass capacity. For example, 80 m³ of cement at 1450 kg/m³ stores about 116 tonnes, while 80 m³ of sand at 1600 kg/m³ stores about 128 tonnes. Moisture and aeration can shift density, so confirm with supplier data. For powders, design with conservative density to avoid overstating tonnage.
Allowances: freeboard, fill limit, and losses
Silos should not be filled to 100%. Freeboard reduces dusting and protects level sensors and vent filters. Apply a fill limit (e.g., 85–95%) and a handling loss (e.g., 1–3%) to estimate usable capacity. Losses include spillage and pneumatic line purge. The calculator reports gross and usable volumes to keep assumptions visible.
Field checks and QA tips
Verify dimensions on drawings: internal diameter, straight-side height, hopper height, and roof rise. Measure in meters, then recheck unit conversions. If internal liners or wear plates are planned, subtract their thickness from the internal radius. Compare the calculated volume against the vendor’s stated capacity and flag differences above 2–3% for review. Remember: capacity is not the same as reliable discharge.
FAQs
1) What dimensions are required for an accurate result?
Use internal diameter, straight-side (cylindrical) height, and any hopper or roof heights. Internal dimensions matter because liners and shell thickness reduce capacity compared with external measurements.
2) How should I enter a hopper that is not a perfect cone?
Approximate it as a cone using the internal top diameter and hopper height. If the hopper is a frustum or has offsets, calculate segments separately and add them as additional cone/cylinder entries.
3) Which bulk density should I use for cement or aggregates?
Use the supplier’s bulk density for the delivered condition. Cement commonly ranges around 1350–1550 kg/m³, while sand and stone vary with moisture and grading. If unsure, select a conservative value.
4) Why does usable capacity differ from gross volume?
Gross volume is pure geometry. Usable capacity applies fill limits and loss allowances to reflect freeboard, sensor clearances, and handling losses. This helps avoid overestimating material on hand.
5) What fill limit is typical on construction silos?
Many sites target 85–95% depending on venting, level sensors, and dust control. Use a lower limit when overpressure risk, foaming, or frequent pneumatic filling is expected.
6) How do the CSV and PDF exports work?
After you calculate, use the export buttons to download the entered inputs and computed results. CSV is ideal for spreadsheets, while PDF creates a shareable one-page record for approvals and site files.