Calculator & Tool Hub
Turn powder data into engineering decisions
Calculate, compare, interpret, and check the assumptions behind the result
Use these powder engineering calculators and tools to convert measured inputs into engineering quantities, compare material states, test process assumptions, and identify when a calculation is not enough on its own.
Calculators & decision tools
Choose the calculation that matches the question
The suite combines numerical calculators with interpretation tools. Each tool states the inputs it needs, the output it produces, and the assumption that can make the result misleading. Use the calculation as part of the engineering decision, not as a substitute for representative measurements or process context.
Showing all 11 tools.
Choose a tool
Select any card above to open the calculator here. Each tool states the equation or screening basis, input requirements, and the limitation that matters most.
Particle Size Distribution Analyzer
Enter particle size and cumulative percent passing as pairs. D-values are interpolated in log(size) only where the requested percentile is bracketed by measured data. The tool never extrapolates beyond the supplied range.
Result
Enter cumulative data and run the analyzer.
Use with care: percentile interpolation depends on the supplied points and interpolation basis. Sampling, dispersion state, measurement principle and weighting basis still determine what the PSD represents.
Minimum Fluidization Velocity
Compare an Ergun force-balance estimate with the Wen–Yu correlation. The Ergun route includes particle sphericity and can use a measured εmf; if εmf is left blank, the tool uses 0.45 as a clearly flagged assumption and reports a 0.40–0.45 sensitivity range.
Result
Enter representative particle and fluid properties. Supply εmf if you know it; otherwise the assumption will be shown in the result.
Use with care: the Ergun route is sensitive to εmf and particle shape. Wen–Yu removes the need to enter εmf and φ separately by using empirical voidage/shape approximations. Broad PSDs, cohesion, mixtures and distributor effects can still shift the measured onset of fluidization.
Packed-Bed Pressure Drop
Use the Ergun equation to estimate pressure gradient and total pressure loss through a packed bed. Sphericity is included explicitly so a nonspherical powder is not silently treated as a bed of perfect spheres.
Result
Use a representative equivalent diameter, sphericity and packed-bed voidage.
Use with care: pressure drop is highly sensitive to voidage and particle shape. PSD, packing method, wall effects and the choice of representative diameter can also shift ΔP substantially. The Ergun coefficients remain empirical.
Terminal Settling Velocity
Iteratively solve the drag-force balance for an isolated spherical particle in a Newtonian fluid using the Clift–Gauvin sphere-drag correlation. The result reports both the Reynolds-number regime and whether it remains inside the nominal correlation range.
Result
The tool iterates between terminal velocity, Reynolds number and drag coefficient.
Use with care: Clift–Gauvin is a sphere-drag correlation and is commonly applied below Re ≈ 3 × 105. Nonsphericity, particle interactions, turbulence, hindered settling, electrostatics and broad PSDs can materially alter real settling or elutriation behavior.
Geldart Classification
Screen gas-fluidization behavior using generalized Grace boundaries for A/B and B/D. The C/A division is shown as a transition band rather than an invented sharp line.
Result
The map uses the entered gas properties to calculate Archimedes number and generalized group boundaries.
Use with care: this remains a screening classification. The A/B boundary is based on the Grace generalized relation, B/D on Ar = 1.45 × 105, and C/A is represented as the published transition interval Ar ≈ 0.31–1.3. Cohesion, moisture, shape, PSD and interparticle forces can still shift actual behavior.
Flow Function / ffc Interpreter
Enter major principal stress σ₁ and unconfined yield strength fc pairs from the same shear-cell flow function. The tool calculates ffc point by point and plots fc against σ₁.
Result
Enter at least one valid stress pair.
Use with care: ffc is stress-dependent. A single coefficient is not a universal material property and does not replace wall-friction data, time consolidation, hopper design or process-specific validation.
Bin / Vessel Capacity
Calculate the internal volume of a cylindrical straight-side section plus a conical or frustum hopper. Define the hopper by either its vertical height or its half-angle measured from vertical.
Result
The hopper is treated as a conical frustum; set outlet diameter to zero for a full cone. Half-angle is measured from vertical.
Use with care: geometric volume is not guaranteed usable capacity. Freeboard, fill pattern, angle of repose, aeration, internal hardware, outlet geometry, segregation and operating limits can reduce practical inventory.
Void Fraction / Porosity
Estimate the fraction of the bulk bed not occupied by solid material from bulk density and the selected particle-density basis.
Result
Use densities that refer to the same material state and a particle-density definition appropriate to the pore structure.
Use with care: the result depends on what the particle-density measurement includes or excludes. Closed pores, accessible pores, envelope density and skeletal density are not interchangeable.
BET Surface Area ↔ Equivalent Diameter
Use the nonporous-sphere relation SSA = 6/(ρd). The result is a geometric equivalent, not automatically a measured particle size.
Result
For a nonporous sphere, d (µm) = 6 / [ρ (g/cm³) × SSA (m²/g)].
Use with care: porous, rough, aggregated or highly nonspherical particles can have large internal or external surface contributions, so the equivalent diameter may differ strongly from laser diffraction or imaging size.
Carr Index & Hausner Ratio
Calculate two empirical packing-response indices from bulk and tapped density measured on a consistent basis.
Result
Bulk and tapped density must use the same unit and sample basis.
Use with care: Carr index and Hausner ratio are empirical screening indicators. Their descriptive bands do not reproduce stress-dependent shear behavior or guarantee performance in a feeder, hopper or process.
Moisture Basis Converter
Keep wet-basis and dry-basis moisture definitions separate when comparing specifications, drying data or mass balances.
Result
Wet basis uses total wet mass as the denominator; dry basis uses dry-solids mass.
Use with care: basis conversion does not change how moisture was measured. Loss on drying, Karl Fischer, water activity and sorption measurements answer different questions.
Quick comparison
Match the engineering question to the calculation
Use the required inputs and the critical limitation to decide whether the calculator is appropriate before relying on the numerical result. A clean equation cannot compensate for a poorly defined particle size, density, moisture basis, bed state, or stress condition.
| Decision question | Tool | Required inputs | Critical limitation |
|---|---|---|---|
| What do D10, D50, D90 and span look like for this cumulative PSD? | PSD Analyzer | Particle size and cumulative % passing | The result inherits the measurement method, sampling, dispersion state, weighting basis and interpolation choice. |
| At what superficial velocity should this bed begin to fluidize? | Minimum Fluidization Velocity | Particle size/density, gas density/viscosity, sphericity, and optional εmf for the Ergun route | The Ergun route is sensitive to εmf and sphericity; Wen–Yu removes those separate inputs through empirical approximations. |
| What pressure drop should this packed bed generate at the stated flow? | Packed-Bed Pressure Drop | Particle size, sphericity, voidage, bed depth, superficial velocity, fluid density and viscosity | Shape, PSD, packing history, wall effects and uncertain voidage can shift ΔP substantially. |
| How fast would an isolated particle settle through the fluid? | Terminal Settling Velocity | Particle size/density, fluid density/viscosity | Clift–Gauvin assumes an isolated sphere; the result reports the Reynolds-number regime and flags values outside its nominal range. |
| Which broad fluidization behavior should this powder be screened against? | Geldart Classification | Characteristic particle size, particle/gas density, and gas viscosity | A/B and B/D use generalized correlations; C/A is a transition band rather than a sharp boundary, and real behavior still depends on cohesion and particle state. |
| How does measured cohesive strength change with consolidation stress? | Flow Function / ffc Interpreter | Multiple σ₁ and fc pairs from the same shear-cell flow function | ffc is stress-dependent and does not replace wall friction, time consolidation or equipment-specific design. |
| How much powder can this cylindrical bin and hopper contain? | Bin / Vessel Capacity | Diameter, straight-side height, hopper height or half-angle, outlet diameter, bulk density and working fill | Geometric capacity is not automatically usable process capacity. |
| How much of the bulk bed volume is void space? | Void Fraction / Porosity | Bulk density and selected particle/skeletal density | The answer changes with the particle-density definition and pore volume included by that measurement. |
| What sphere diameter corresponds to this BET area and density? | BET ↔ Equivalent Diameter | Specific surface area and density, or equivalent diameter and density | Porous, rough or nonspherical particles can make the geometric equivalent very different from measured particle size. |
| How strongly does tapping change the packing state? | Carr Index & Hausner Ratio | Bulk and tapped density | These empirical indices do not reproduce stress-dependent shear behavior or guarantee process flow. |
| Are these two moisture values actually on the same basis? | Moisture Basis Converter | Moisture % and wet/dry basis | Basis conversion does not reconcile differences between LOD, Karl Fischer, water activity or sorption methods. |
A calculation narrows the engineering question. Use the linked PTI property, process, troubleshooting and test-method pages to decide whether the assumptions and input data represent the real powder state.
Connect the result
Move from the number to the physical meaning
A calculation becomes useful only when the inputs and output are connected to the measured material state, the governing powder behavior, and the process decision it is intended to support.
Need measured inputs or experimental validation? PowderTechnology.info works closely with Delft Solids Solutions, a contract research organization specializing in the characterization of powders and granules. A calculator is only as useful as the inputs and assumptions behind it. DSS can generate representative particle-size, density, flow, porosity, surface-area, permeability and other data, or test whether a calculated process expectation matches the actual material response.
