# Bulk Density & Porosity Calculator

Bulk density and porosity for granular or porous materials. Three-way solver: pick the unknown (ρ_bulk, m, or V) and supply the other two. ρ_bulk = m/V_bulk. Optionally enter the true particle density ρ_true to compute porosity ε = 1 − ρ_bulk/ρ_true, plus relative density against water. SI units (kg, m³, kg/m³).

> Canonical page: https://elysiatools.com/en/tools/bulk-density-calculator

- **Category:** Math & Numbers

- **Keywords:** bulk density, apparent density, porosity, void fraction, true density, particle density, relative density, specific gravity, granular material, particulate, materials science

## Overview

The Bulk Density & Porosity Calculator finds bulk density, mass, or bulk volume for granular and porous materials using SI units. Enter any two related values, and optionally add true particle density to calculate porosity and relative density.

## Inputs

- **Solve for** (select)
- **Bulk Density ρ (kg/m³)** (number): Bulk (apparent) density in kg/m³. Required when solving for mass or volume.
- **Mass m (kg)** (number): Mass of the material in kg. Required when solving for density or volume.
- **Bulk Volume V (m³)** (number): Bulk volume (including voids) in m³. Required when solving for density or mass.
- **True Particle Density ρ_true (kg/m³, optional)** (number): True (particle) density of the solid material itself, no pores. Optional — when given, porosity ε = 1 − ρ_bulk/ρ_true is reported. Quartz ≈ 2650, steel ≈ 7850 kg/m³.
- **Decimal Places** (number)

## When to use

- Calculate bulk density from a material sample's mass and bulk volume.
- Find the mass or bulk volume when density and the other measurement are known.
- Estimate porosity for a granular or porous material when true particle density is available.

## How it works

- Choose whether to solve for bulk density, mass, or bulk volume.
- Enter the other two values in kg, m³, or kg/m³.
- Optionally enter true particle density to calculate porosity.
- Set the number of decimal places and review the JSON result with the calculated values.

## Use cases

- Characterize sand, powders, aggregates, and other granular materials.
- Estimate void fraction in porous solids using measured bulk and true densities.
- Plan material quantities by converting between mass, bulk volume, and bulk density.

## Frequently asked questions

### What formula is used for bulk density?

Bulk density is calculated as ρ_bulk = m/V, where m is mass in kg and V is bulk volume in m³.

### Can I solve for mass or volume instead of density?

Yes. Select mass or volume as the unknown and provide the other two required values.

### How is porosity calculated?

When true particle density is provided, porosity is calculated as ε = 1 − ρ_bulk/ρ_true.

### What units does the calculator use?

The calculator uses kilograms for mass, cubic metres for volume, and kilograms per cubic metre for density.

### What is relative density based on?

Relative density is calculated by comparing bulk density with water at 1000 kg/m³.

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