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Chemistry

Henderson-Hasselbalch

Same as buffer pH. Free online Henderson-Hasselbalch. Calculate henderson-hasselbalch online — fast, accurate, mobile-friendly, no signup needed.

pH
4.76

Derivation

  1. ├── 01Givenpka = 4.76, ratio = 1
  2. ├── 02Formulat+log₁₀(a)
  3. └── 03Compute pH4.76
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§01What is

Understanding the Henderson-Hasselbalch

The Henderson-Hasselbalch computes pH from 2 inputs: pka, [a⁻]/[ha]. Same as buffer pH.

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 Henderson-Hasselbalch sits in that toolkit — it same as buffer pH. 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)

Where

pka
pKa
ratio
[A⁻]/[HA]
§03Practical Example

Step-by-step walkthrough

Scenario

Apply the formula to a realistic set of inputs: pKa = 4.76, [A⁻]/[HA] = 1.

  1. 01Start by noting the input — pKa: 4.76.
  2. 02Start by noting the input — [A⁻]/[HA]: 1.
  3. 03Substitute these values into the formula: t+log₁₀(a)
  4. 04Compute pH: the calculator returns 4.76.
  5. 05Cross-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 Henderson-Hasselbalch 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

[A⁻]/[HA] halved

ratio = 0.5 (from 1)

Keep every other input at its default and halve the [a⁻]/[ha]. See how ph responds.

  1. 01New [A⁻]/[HA]: 0.5
  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

[A⁻]/[HA] doubled

ratio = 2 (from 1)

Keep every other input at its default and double the [a⁻]/[ha]. See how ph responds.

  1. 01New [A⁻]/[HA]: 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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