Rex says
The fast lane for the math you almost remember from school. Type the numbers, get the answer, move on with your day.
Try a scenario
Click to load — tweak from there.Inputs
Result
pH
4.00
pOH
10.00
[OH⁻] (mol/L)
0.0000000001
Classification
Acidic
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One click, a permanent link with your numbers baked in.
How to use this
- 1Enter [h⁺] concentration (mol/L).
- 2Read your ph on the right — it updates as you type.
- 3Hit Share to keep the scenario or send it to someone.
About this calculator
pH is the negative log of hydrogen-ion concentration. Enter molarity to get pH, or work back from pH to concentration.
Worked example
Using the values the calculator loads with:
Inputs
- [H⁺] concentration: 0.0001 mol/L
Results
- pH: 4
- pOH: 10
- [OH⁻] (mol/L): 0.0000000001
- Classification: Acidic
What each field means
Inputs
- [H⁺] concentration (mol/L)
- The [h⁺] concentration used in the calculation, measured in mol/L. Starts at 0.0001 mol/L so you have a working example on load.
Results
- pH
- Returned as a decimal number and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- pOH
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- [OH⁻] (mol/L)
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Classification
- Returned as a plain value. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
How does the ph and poh calculator work?
pH is the negative log of hydrogen-ion concentration. Enter molarity to get pH, or work back from pH to concentration. The underlying maths is: pH = −log₁₀[H⁺]; pH + pOH = 14
What do I need to enter?
Just one value: [h⁺] concentration. Each field starts with a sensible default, so you can change one number at a time and watch the result move.
What does the ph result mean?
It is returned as a decimal number and updates live as you edit the inputs, so you can compare two or three versions of a scenario in a few seconds.
Is this calculator free, and do I need an account?
Yes, it's free, and no account is required. Nothing you type is stored on our servers — the maths runs entirely in your browser.
How accurate is the result?
It applies the standard formula exactly, so the arithmetic is precise. Results are rounded for display; the underlying calculation keeps full precision.
Who is this tool for?
It's built for students, developers, and anyone who needs the answer right now without setting up a spreadsheet.
Accuracy and limitations
- Results are rounded for display; the underlying calculation keeps full precision.
- Very large or very small inputs may hit floating-point limits in the browser.
- Inputs outside the accepted range are clamped rather than rejected.
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). pH Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/ph-calculator
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/ph-calculator" target="_blank" rel="noopener">pH Calculator — RevenueLab</a> (2026).</p>
Source: [pH Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/ph-calculator) (2026).