How it works
- 1Enter the requested chemistry values, formula or equation.
- 2Check units and leave a field blank only when the tool is designed to solve for an unknown.
- 3Run the calculation and review the result, formula and supporting breakdown.
← Chemistry Calculators & Laboratory Tools
BROWSER · Toolardo Chemistry Core (local JavaScript)
I need to calculate pH / pOH
pH / pOH Calculator
Convert among pH, pOH, hydrogen-ion concentration and hydroxide-ion concentration using Kw = 1.0×10⁻¹⁴ at 25 °C.
✓ Runs locally in your browser✓ No account required✓ Deterministic formula-based calculation
pH
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pOH
—
[H⁺]
—
[OH⁻]
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At 25 °C: pH + pOH = 14; Kw = 1.0 × 10⁻¹⁴
This is an ideal concentration-based calculation at 25 °C; activities and temperature-dependent pKw are not included.
About this tool
At 25 °C the tool uses pH + pOH = 14 and Kw = [H⁺][OH⁻] = 1.0×10⁻¹⁴.
Common uses
pH calculatorpOH calculatorH+ concentration calculatorOH concentration calculator
Frequently asked questions
Why does pH + pOH equal 14?
That relation follows from Kw = 1.0×10⁻14 at 25 °C. At other temperatures, pKw changes.
Can pH be below 0 or above 14?
Yes for sufficiently concentrated solutions; the familiar 0–14 range is not a universal hard limit.
Does this include activity coefficients?
No. This is an ideal concentration-based calculation.
Does this calculation run on a server?
No. The calculation runs locally in your browser with JavaScript.
Can I use the result directly in laboratory work?
Use it as a calculation aid and verify reagent form, purity, constants, assumptions and your laboratory SOP before operational use.