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Chemistry

pH Calculator

pH from hydrogen ion concentration. Free online pH Calculator. Calculate ph online — fast, accurate, mobile-friendly, no signup needed.

pH = −log₁₀[H⁺]. 0–6 acidic, 7 neutral, 8–14 basic.
pH
3

Derivation

  1. ├── 01GivenH = 0.001
  2. ├── 02Formula{let t=e.H;return-log₁₀(t)}
  3. ├── 03Substitute{let t=e.0.001;return-log₁₀(t)}
  4. └── 04Compute pH3
Did you know?

Søren Sørensen invented the pH scale in 1909 while studying protein chemistry at the Carlsberg brewery — "p" stands for "potenz" (power) and "H" for hydrogen.

§01What is

Understanding the pH Calculator

The pH Calculator computes pH from 1 input: [h⁺] (m). pH from hydrogen ion concentration.

Chemistry turns grams and moles into reactions. Getting the stoichiometry, dilutions, or concentrations right is the difference between a lab result you can trust and one you can’t reproduce. The pH Calculator sits in that toolkit — it pH from hydrogen ion concentration. Enter your numbers above and the result updates instantly; every step of the math is shown in the Derivation panel so you can see exactly how the answer was reached.

§02The Formula

How it’s calculated

{let t=e.H;return-log₁₀(t)}

Where

H
[H⁺] (M)
§03Practical Example

Step-by-step walkthrough

Scenario

Apply the formula to a realistic set of inputs: [H⁺] (M) = 0.001.

  1. 01Start by noting the input — [H⁺] (M): 0.001.
  2. 02Substitute these values into the formula: {let t=e.H;return-log₁₀(t)}
  3. 03Compute pH: the calculator returns 3.
  4. 04Cross-check the answer by opening the Derivation panel above — every line of math is shown so you can follow the computation end-to-end.
§04Variants

Common pH Problems

The formula gets rearranged depending on which variable you need. Here are the patterns you’ll run into in the real world — find the one that matches your problem and follow the worked steps.

01 · PATTERN

[H⁺] (M) halved

H = 0.0005 (from 0.001)

Keep every other input at its default and halve the [h⁺] (m). See how ph responds.

  1. 01New [H⁺] (M): 0.0005
  2. 02Baseline pH: 3
  3. 03New pH: 3.30103
  4. 04pH increases by 10% → use this sensitivity to plan for real-world variation.
02 · PATTERN

[H⁺] (M) doubled

H = 0.002 (from 0.001)

Keep every other input at its default and double the [h⁺] (m). See how ph responds.

  1. 01New [H⁺] (M): 0.002
  2. 02Baseline pH: 3
  3. 03New pH: 2.69897
  4. 04pH decreases by 10% → use this sensitivity to plan for real-world variation.
§05FAQ

Frequently asked questions

Yes. The calculator implements the standard formula as documented and returns exact floating-point results. No approximations are used unless noted in the formula.
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