pOH Calculator
Calculate pOH from hydroxide concentration and convert to pH.
About pOH Calculator
pOH mirrors pH for bases. Since the ion product of water fixes [H⁺][OH⁻] at 10⁻¹⁴ at 25 °C, either quantity determines the other completely. Working in pOH is more natural for basic solutions, and it avoids handling very small hydrogen ion concentrations.
Formula
pOH
pOH = −log₁₀[OH⁻]; pH = 14 − pOH at 25 °C
- [OH⁻]
- Hydroxide ion concentration in moles per litre
Worked example
With the default values below, pOH Calculator returns pOH of 4.0000. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Hydroxide ion concentrationminimum 0 mol/L
- 0.0001 mol/L
Results
- pOH
- 4.0000
- pH
- 10.0000
- Hydrogen Ion Concentration
- 0.00000000010000 mol/L
- Classification
- Basic
- Times More Basic Than Neutral Water
- 1,000.00
Step by step
- 1Values used
- 2pOH
- 3pOH= 4.0000
- 4pH= 10.0000
- 5Hydrogen Ion Concentration= 0.00000000010000 mol/L
- 6Classification= Basic
- 7Times More Basic Than Neutral Water= 1,000.00
Assumptions and limits
- The result is derived only from the single input listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 14 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is pOH calculated?
pOH = −log₁₀[OH⁻]; pH = 14 − pOH at 25 °C pOH mirrors pH for bases. Since the ion product of water fixes [H⁺][OH⁻] at 10⁻¹⁴ at 25 °C, either quantity determines the other completely.
Why does pOH matter?
Working in pOH is more natural for basic solutions, and it avoids handling very small hydrogen ion concentrations.
What values do I need to enter?
This calculator takes 1 input: Hydroxide ion concentration. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.