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Chemistry

Buffer pH Calculator

Henderson-Hasselbalch equation. Free online Buffer pH Calculator. Calculate buffer ph online — fast, accurate, mobile-friendly, no signup needed.

Henderson–Hasselbalch: pH = pKa + log([A⁻]/[HA]).
pH
4.76

Derivation

  1. ├── 01Givenpka = 4.76, base = 0.1, acid = 0.1
  2. ├── 02Formulat+log₁₀(a / n)
  3. └── 03Compute pH4.76
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 Buffer pH Calculator

The Buffer pH Calculator computes pH from 3 inputs: pka, [base], [acid]. Henderson-Hasselbalch equation.

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 Buffer pH Calculator sits in that toolkit — it henderson-Hasselbalch equation. 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

t+log₁₀(a / n)

Where

pka
pKa
base
[base]
acid
[acid]
§03Practical Example

Step-by-step walkthrough

Scenario

Apply the formula to a realistic set of inputs: pKa = 4.76, [base] = 0.1, [acid] = 0.1.

  1. 01Start by noting the input — pKa: 4.76.
  2. 02Start by noting the input — [base]: 0.1.
  3. 03Start by noting the input — [acid]: 0.1.
  4. 04Substitute these values into the formula: t+log₁₀(a / n)
  5. 05Compute pH: the calculator returns 4.76.
  6. 06Cross-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 Buffer 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

pKa halved

pka = 2.38 (from 4.76)

Keep every other input at its default and halve the pka. See how ph responds.

  1. 01New pKa: 2.38
  2. 02Baseline pH: 4.76
  3. 03New pH: 2.38
  4. 04pH decreases by 50% → use this sensitivity to plan for real-world variation.
02 · PATTERN

pKa doubled

pka = 9.52 (from 4.76)

Keep every other input at its default and double the pka. See how ph responds.

  1. 01New pKa: 9.52
  2. 02Baseline pH: 4.76
  3. 03New pH: 9.52
  4. 04pH increases by 100% → use this sensitivity to plan for real-world variation.
03 · PATTERN

[base] halved

base = 0.05 (from 0.1)

Keep every other input at its default and halve the [base]. See how ph responds.

  1. 01New [base]: 0.05
  2. 02Baseline pH: 4.76
  3. 03New pH: 4.45897
  4. 04pH decreases by 6.3% → use this sensitivity to plan for real-world variation.
04 · PATTERN

[base] doubled

base = 0.2 (from 0.1)

Keep every other input at its default and double the [base]. See how ph responds.

  1. 01New [base]: 0.2
  2. 02Baseline pH: 4.76
  3. 03New pH: 5.06103
  4. 04pH increases by 6.3% → 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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