Soil Bulk Density Calculator

Calculator Inputs

Sample Name

Oven-Dry Soil Mass

Mass Unit

Wet Soil Mass (Optional)

Particle Density

Volume Method

Direct Sample Volume

Direct Volume Unit

Cylinder Diameter

Cylinder Height

Length

Width

Depth

Dimension Unit

Coarse Fragment Volume

Coarse Volume Unit

Notes (Optional)

Example Data Table

Sample	Dry Mass (g)	Diameter (cm)	Height (cm)	Total Volume (cm³)	Coarse Volume (cm³)	Fine-Earth Volume (cm³)	Dry Bulk Density (g/cm³)
A1	235.0	5.0	10.0	196.35	8.00	188.35	1.2477
B2	268.0	5.4	9.8	224.39	10.00	214.39	1.2501
C3	310.0	6.0	10.0	282.74	15.00	267.74	1.1575

Formula Used

Dry Bulk Density = Oven-Dry Soil Mass ÷ Corrected Sample Volume

Corrected Sample Volume = Total Sample Volume − Coarse Fragment Volume

Cylinder Volume = π × (Diameter ÷ 2)² × Height

Rectangular Volume = Length × Width × Depth

Wet Bulk Density = Wet Soil Mass ÷ Corrected Sample Volume

Gravimetric Moisture (%) = ((Wet Mass − Dry Mass) ÷ Dry Mass) × 100

Porosity (%) = (1 − (Bulk Density ÷ Particle Density)) × 100

Void Ratio = Porosity Fraction ÷ (1 − Porosity Fraction)

How to Use This Calculator

Enter a sample name for easy identification.
Input the oven-dry soil mass and choose its unit.
Optionally enter wet mass to estimate moisture and wet bulk density.
Select the sample volume method: direct, cylinder, or rectangular.
Enter the required volume or dimensions and choose dimension units.
Add coarse fragment volume if stones or gravel occupied part of the sample.
Set particle density, usually 2.65 g/cm³ for mineral soils.
Press the calculate button to show results above the form.
Use the export buttons to download a CSV or PDF summary.

FAQs

1. What is soil bulk density?

Soil bulk density is the oven-dry mass of soil divided by the total sample volume. It reflects packing, pore space, and compaction within a sampled soil volume.

2. Why use oven-dry mass instead of wet mass?

Oven-dry mass removes water variability. That makes samples comparable across sites, seasons, and methods. Wet mass is still useful for estimating moisture and wet bulk density.

3. Why does the calculator ask for coarse fragment volume?

Stones and coarse fragments can occupy space without contributing fine-earth soil. Subtracting their volume improves the density estimate for the actual fine soil matrix.

4. What particle density should I enter?

A common default is 2.65 g/cm³ for many mineral soils. Organic soils, volcanic soils, and unusual mineralogy may require a different measured value.

5. What units does the calculator support?

The form accepts several mass, volume, and dimension units. All values are internally converted so the final density remains consistent and easy to compare.

6. What does a high bulk density usually indicate?

Higher bulk density often suggests compaction, lower pore space, and greater root resistance. Interpretation still depends on soil texture, structure, organic matter, and land use.

7. Can this calculator estimate porosity?

Yes. When particle density is provided, the calculator estimates porosity from dry bulk density. The result is an approximation unless particle density is directly measured.

8. Is this calculator suitable for laboratory and field work?

Yes. It is useful for core samples, lab sheets, and field summaries. Still, follow your site protocol for sampling depth, drying temperature, and fragment handling.