Water Potential Calculator
Calculate the total water potential of soil using the sum of matric, gravitational, pressure, and osmotic potentials. Useful for agriculture, hydrology, and environmental science.
Published by:
isCalculator Editorial Team
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How to use this tool?
This calculator computes the total water potential (Ψtotal) by summing its four components. All values must be entered in megapascals (MPa).
- Enter component values in the four fields:
- Matric Potential (Ψm) – typically negative (e.g., -0.3)
- Gravitational Potential (Ψg) – positive for upward movement
- Pressure Potential (Ψp) – positive for turgor pressure
- Osmotic Potential (Ψo) – typically negative (e.g., -0.1)
- Click "Calculate Total Water Potential" – the button validates all inputs are numbers.
- Read the result – the total appears in MPa with the full formula breakdown below it.
Tip: Use negative values for matric and osmotic potentials as they reduce total water potential. The calculator rounds to three decimal places.
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Frequently Asked Questions
Water potential is the potential energy of water per unit volume relative to pure water, often expressed in megapascals (MPa). It determines the direction of water movement in soil and plants.
The components are matric potential (due to capillary and adsorptive forces), gravitational potential (due to elevation), pressure potential (due to hydrostatic pressure), and osmotic potential (due to solutes).
A negative total water potential indicates water is bound or under tension; a positive value indicates free water under pressure. In soils, typical values range from 0 (saturated) to -1.5 MPa (permanent wilting point).