Science & Engineering

pOH Calculator

Calculates pOH from hydroxide ion concentration using pOH = -log10[OH-], then reports pH as 14 minus pOH. Enter 0.0001 mol/L to get pOH 4 and pH 10.

What this calculator does

The pOH Calculator estimates your result instantly from the values you enter, using standard science & engineering formulas. Calculates pOH from hydroxide ion concentration using pOH = -log10[OH-], then reports pH as 14 minus pOH. Enter 0.0001 mol/L to get pOH 4 and pH 10. Calculations run in your browser, so nothing you type is sent to a server, and the output is an estimate rather than a certified or official figure.

pOH Calculator

Result

—
pOH
—
pH

About pOH Calculator

This tool finds the pOH of a solution from its hydroxide ion concentration using pOH = −log10[OH−], and returns the matching pH as 14 − pOH. Enter the [OH−] concentration in mol/L to see both.

Formula & Mathematical Calculation

pOH = f([OH⁻] Concentration (mol/L))

Calculated according to standard science formulas implemented in the calculator core.

Calculation Example

For [OH−] = 0.0001 mol/L: pOH = −log10(0.0001). The pOH box shows 4 and the pH box shows 10, with the note pOH = -log[OH⁻] = 4, so pH = 14 − pOH = 10.

Key Benefits

  • Computes pOH from hydroxide ion concentration with pOH = -log10[OH-]
  • Derives the matching pH as 14 - pOH automatically
  • Rounds pOH and pH to three decimal places
  • Displays both values side by side

How to Use this Calculator

  1. Enter the hydroxide ion concentration
    Type the [OH-] concentration in mol/L into the input field, for example 0.0001.
  2. Calculate
    Click Calculate to run the pOH formula.
  3. Read pOH and pH
    The result shows pOH in one box and the derived pH in the other.

Assumptions & Limitations

What the calculation assumes

  • Every value you enter is treated as an exact, known amount.
  • Any rate or interval you enter is assumed to hold for the whole period unless the form asks for it separately.
  • Results use standard published formulas and account only for the values entered above.
  • Rounding is applied for display; the underlying calculation uses your full precision.
  • Results are returned in the same units you enter, unless the tool states the output unit.

What it does not cover

  • pOH Calculator produces a calculated result for reference and learning, not a certified or official measurement.
  • Real-world outcomes differ when tolerances, rounding rules or local standards apply.
  • Definitions and standards vary by region and change over time; verify the convention that applies to your case.
  • Figures are only as accurate as the inputs you supply — check them before acting on the result.
  • For work where the result carries real consequences, confirm it against an authoritative source.

Frequently Asked Questions

It computes pOH = -log10[OH-] and then sets pH = 14 - pOH.

A single value: the hydroxide ion concentration [OH-] in mol/L.

The logarithm is undefined at zero, so the tool requires a concentration greater than 0.

Yes. This one starts from hydroxide [OH-] to find pOH first, while the pH calculator starts from hydrogen [H+].

Free to use, no account needed. Calculations run in your browser, so nothing you type is sent to a server. Results are estimates — how we build and check our calculators.