Tank Fill • V_fill = V_tot × (d / h)³

Partial Cone & Tank Fill Calculator (Liquid Depth Solver)

Calculate liquid volume, percentage full, and remaining ullage capacity in a conical tank or hopper oriented with its apex at the bottom. Uses the cubic scaling law of similar geometric solids to convert dipstick depth into precise volume.

Input Dimensions

Adjust values below to compute instant results in real time.
R
h_tot
d
h_tot d (depth) r_d R (top) Cubic fill scaling: $V_{ ext{fill}} = V_{ ext{total}} imes (d / h_{ ext{tot}})^3$
Calculated Result
0.0000 cm³
Secondary Metric 1
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Secondary Metric 2
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Equivalent Unit Conversions
Litres (L) —
Millilitres (mL) —
Cubic Metres (m³) —
US Gallons (gal) —
UK Imp Gallons —
Cubic Feet (ft³) —
Step-by-Step Proof

Mathematical Calculation Steps

How the Formula Works & Geometric Derivation

In Euclidean solid geometry, a cone is formed by connecting a planar circular base to an apex vertex point via a continuous curved lateral surface. The governing equation for this calculator is:

Governing Equation
$$V_{\text{fill}} = \frac{\pi R^2 h_{\text{total}}}{3} \left(\frac{d}{h_{\text{total}}}\right)^3 = V_{\text{total}} \left(\frac{d}{h_{\text{total}}}\right)^3$$

Liquid volume scales with the cube of the liquid depth ratio (d / h_total).

This mathematical relationship originates from integral calculus. By slicing the conical volume into infinitesimal horizontal circular disks of thickness $dz$ from the apex ($z = 0$) down to the base altitude ($z = h$), each disk at level $z$ possesses a radius $r(z) = rac{r}{h}z$. The volume integral is evaluated as:

$$V = \int_0^h \pi [r(z)]^2 dz = \pi \frac{r^2}{h^2} \int_0^h z^2 dz = \pi \frac{r^2}{h^2} \left[ \frac{z^3}{3} \right]_0^h = \frac{1}{3} \pi r^2 h$$

Variables and Parameters Reference

Below is a breakdown of every mathematical symbol and physical dimension used across this calculator:

Symbol Parameter Name Definition & Geometric Meaning
V_fill Liquid Fill Volume Volume of liquid currently stored up to depth d
V_tot Total Tank Capacity Maximum liquid capacity when filled to the top rim
V_rem Remaining Capacity Ullage or empty volume remaining: V_tot - V_fill
R Top Rim Radius Radius of the top circular opening of the cone
h_tot Total Vertical Height Full vertical height from bottom apex to top rim
d Liquid Depth Measured liquid level from bottom apex upward
r_d Liquid Surface Radius Radius of the liquid surface at depth d: r_d = R × (d / h_tot)

Worked Example: Liquid in a Half-Full Depth Conical Funnel

Problem Statement: A conical tank has top radius R = 100 cm and total height h_tot = 200 cm. Liquid is filled to depth d = 100 cm (halfway up). Find the liquid volume and fill percentage.

  1. Compute total tank capacity: V_tot = (1/3) × π × (100)² × 200 = (2,000,000π / 3) ≈ 2,094,395 cm³ (~2,094.4 Liters).
  2. Find depth ratio: d / h_tot = 100 / 200 = 0.5 (half height).
  3. Apply cubic law: (0.5)³ = 0.125 (only 12.5% of total volume!).
  4. Compute liquid volume: V_fill = 2,094.4 × 0.125 = 261.8 Liters.
  5. Key insight: Even though the dipstick reads 50% depth, the tank only holds 12.5% of its total capacity because cones narrow toward the apex!

Practical Applications & Real-World Use Cases

Conical mathematics is widely applied across aerospace engineering, industrial manufacturing, food science, civil earthworks, and architectural design:

  • Brewing & winemaking: monitoring batch volumes inside conical fermentation tanks.
  • Agriculture: grain and seed fill level inventory in conical-bottom silos and hoppers.
  • Water treatment: gauging sludge settle volume in conical clarifiers and thickeners.
  • Chemical processing: automated liquid level dip transmitter calibration for conical reaction vessels.

Frequently Asked Questions

Authoritative answers on cone formulas, common pitfalls, and calculation methods.

For a cone filled from its apex, the liquid forms a smaller, similar cone. If d is the liquid depth measured upward from the apex, the volume is V = (πR²H / 3) × (d/H)³, where R and H are the full cone's radius and height.

An inverted cone uses the same geometric volume formula as an upright cone. However, the liquid depth must be measured from the correct reference point. For a tank with its apex at the bottom, the liquid depth is measured from that bottom apex.

For a cone filled from its apex, the fraction of total volume filled is (d/H)³. Multiply this fraction by 100 to obtain the percentage full. This relationship applies to a geometrically similar, upright or inverted conical tank filled from its apex.

No. If a cone is filled from its apex to half its total height, it contains one-eighth of the full cone's volume. The radius of the liquid surface is also half the base radius because the smaller liquid cone is geometrically similar to the full cone.

Yes. Subtract the current liquid volume from the total cone volume. The result is the remaining capacity, provided the tank has the same conical geometry throughout and there are no additional sections that need to be included.

Cone height is the full perpendicular distance from the apex to the base. Liquid depth is the distance from the apex to the current liquid surface for a cone filled from its apex. Using the wrong reference point can produce an incorrect fill volume.

Yes, for the conical section of the tank. If the tank also contains a cylindrical section, calculate that section separately and combine the volumes as appropriate. The result should reflect the actual tank shape and the liquid level.

Yes. First calculate the liquid volume in consistent units, then convert it into litres, US gallons, or imperial gallons. The calculator should clearly label the selected unit system because US and imperial gallons have different conversion factors.

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