Buffer Solution pH Calculator
Buffer pH from the Henderson-Hasselbalch equation.
Enter your values
Enter the acid pka you are working with.
Enter the conjugate base concentration in M.
Enter the weak acid concentration in M.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Buffer pH
- 4.76
- Ratio [base]/[acid]
- 1
- pKa used
- 4.76
Quick answer
pH = pKa + log10([base]/[acid]).
pH = pKa + log10([A-]/[HA])
At a glance
| What it does | Buffer pH from the Henderson-Hasselbalch equation. |
|---|---|
| Category | Science |
| Inputs needed | Acid pKa, Conjugate base concentration, Weak acid concentration |
| Main output | Buffer pH |
| Formula | pH = pKa + log10([A-]/[HA]) |
| Cost | Free — no sign-up, no download |
How to use the Buffer Solution pH Calculator
- 1Enter the pKa of the weak acid (4.76 for acetic acid is a common example).
- 2Enter the concentrations of the conjugate base and the weak acid.
- 3Read the resulting buffer pH.
Inputs explained
- Acid pKa
- Enter the acid pka you are working with.
- Conjugate base concentration(M)
- Enter the conjugate base concentration in M.
- Weak acid concentration(M)
- Enter the weak acid concentration in M.
Worked example
Using the values the calculator loads with:
Inputs
- Acid pKa4.76
- Conjugate base concentration0.1 M
- Weak acid concentration0.1 M
Results
- Buffer pH4.76
- Ratio [base]/[acid]1
- pKa used4.76
Frequently asked questions
What makes a good buffer?
A buffer works best within 1 pH unit of the acid's pKa, where the base-to-acid ratio stays balanced.
What if the ratio is 1:1?
When base and acid concentrations are equal, pH equals pKa exactly since log10(1) = 0.
What do I need to enter into the Buffer Solution pH Calculator?
Just 3 values: acid pka, conjugate base concentration, weak acid concentration. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Buffer Solution pH Calculator work out the answer?
pH = pKa + log10([base]/[acid]). It applies the formula pH = pKa + log10([A-]/[HA]) and shows the working so you can check each step by hand.
Is the Buffer Solution pH Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.