Buffer Recipe — Calculator

How it works: pick a buffer system (or define a custom one), set your target pH, concentration and volume, then choose a preparation method. The calculator applies the Henderson–Hasselbalch equation (pH = pKa + log([A−]/[HA])) to work out the acid/base ratio and gives you a ready-to-follow recipe — by weighing both forms, by titrating with NaOH or HCl, or by mixing stock solutions. Optional temperature correction of pKa and an NaCl addition for ionic strength are included.

Target Parameters

Target pH

Buffer concentration

Final volume

Use temperature (pKa correction)

°C

Model

pH = pKa + log([A⁻]/[HA])

pKa_eff = pKa₂₅ + (ΔpKa/ΔT)·(T_use − 25)

Buffer System — auto-selected by target pH

All buffer systems (manual override)

pKa (25 °C)

Effective pKa (calc)

Acid form (HA)

Component

Formula

MW (g/mol)

Base form (A⁻) — pick the conjugate base, or leave “— none —” to titrate with NaOH

Component

Formula

MW (g/mol)

Preparation Method

Mix acid & base forms
Weigh both solid forms by mass Titrate acid form with NaOH
Weigh acid form, add strong base Titrate base form with HCl
Weigh base form, add strong acid Mix stock solutions
Blend acid & base stocks

Per-method chemistry

n_total = C·V ; n_HA = n_total·f_acid ; n_A− = n_total·f_base

titration: n_NaOH = n_A− | n_HCl = n_HA | V_stock = n / C_stock

Additional Salt (optional)

Add NaCl

NaCl concentration

NaCl mass (calc)

Ionic strength (approx.)

I ≈ ½Σc_iz_i² (buffer + NaCl contributions, monovalent model)

Recipe & Results

Components

Component	Form / stock	Moles	Amount

Step-by-step preparation

Acid / base composition

HA 0%

A⁻ 0%

Acid form (HA) [A⁻]/[HA] = — Base form (A⁻)

Buffer species distribution

Fraction of acid (HA) and base (A⁻) versus pH. The marker shows your target pH and its species split.

Acid fraction (HA) Base fraction (A⁻) Target pH