Calculator Input
Formula Used
| Method | Formula | Meaning |
|---|---|---|
| Direct volumetric | θv = Vw / Vt | Volumetric water content equals water volume divided by total soil volume. |
| Gravimetric content | θg = (Mwet - Mdry) / Mdry | Gravimetric water content uses wet and dry mass difference. |
| Gravimetric to volumetric | θv = θg × (ρb / ρw) | Converts gravimetric moisture to volumetric moisture using densities. |
| Degree of saturation | S = θv / n | Shows how much of pore space is filled with water. |
| Air-filled porosity | nair = n - θv | Remaining pore space still occupied by air. |
Keep units consistent before applying formulas. The calculator handles common conversions for volume, mass, and density automatically.
How to Use This Calculator
- Select the calculation mode.
- Use the direct method when water volume and total sample volume are known.
- Use the gravimetric conversion when wet mass, dry mass, and bulk density are available.
- Optionally enter porosity to estimate degree of saturation and air-filled porosity.
- Click the calculate button to show the result above the form.
- Review the result table, moisture interpretation, and Plotly chart.
- Use the CSV or PDF buttons to export the computed summary.
Example Data Table
| Case | Mode | Input Summary | Volumetric Content | Extra Output |
|---|---|---|---|---|
| Example 1 | Direct | Water = 180 cm³, Total = 900 cm³, Porosity = 45% | 0.2000 = 20.00% | Saturation = 44.44% |
| Example 2 | Direct | Water = 0.32 L, Total = 1.60 L, Porosity = 50% | 0.2000 = 20.00% | Air-filled porosity = 30.00% |
| Example 3 | Gravimetric | Wet = 620 g, Dry = 500 g, Bulk density = 1.30 g/cm³ | 0.3120 = 31.20% | Gravimetric content = 0.2400 |
| Example 4 | Gravimetric | Wet = 1.85 kg, Dry = 1.50 kg, Bulk density = 1450 kg/m³ | 0.3383 = 33.83% | Useful for cross-checking field samples |
FAQs
1) What is volumetric soil moisture content?
It is the fraction of a soil sample’s total volume occupied by water. It may be written as a decimal, such as 0.25, or as a percentage, such as 25%.
2) Why use volumetric content instead of gravimetric content?
Volumetric content is easier to compare with pore space, irrigation depth, and root-zone storage. Gravimetric content is mass-based, so it often needs density data before practical field interpretation.
3) When should I use the direct volumetric method?
Use it when you already know the water volume and the total soil sample volume. This is common in controlled sampling, lab cylinders, and calibration work.
4) When should I use the gravimetric conversion method?
Use it when you measured wet mass and dry mass and also know the bulk density. This route is common after oven-dry testing and laboratory moisture analysis.
5) What does porosity add to the result?
Porosity lets you estimate the degree of saturation and the air-filled pore space. Those values help with drainage, aeration, and root-zone condition checks.
6) Can volumetric content be more than 100%?
Under normal physical conditions, no. A result above 100% usually means inconsistent units, incorrect density values, or measurement errors in wet mass, dry mass, or volume.
7) Does soil type affect interpretation?
Yes. Clay, silt, sand, and organic soils can hold different amounts of water at the same volumetric content. Always interpret values alongside texture and field conditions.
8) What export options are included?
The calculator provides CSV and PDF export buttons after a successful calculation. They capture the result table so you can save, print, or share the summary.