pH to Hydrogen-Ion Concentration Converter

pH is a logarithm, so the gap between pH 6 and pH 7 is a ten-fold change in hydrogen-ion concentration, not a one-unit difference. This converter turns any pH into mol/L, mmol/L or g/L of H⁺ and back, showing the exact relation and the worked values.

Convert ph to hydrogen-ion concentration units

Value

From

Why pH is not a linear scale

pH = −log₁₀[H⁺], so each whole unit is a factor of ten in hydrogen-ion concentration. pH 5 has ten times the H⁺ of pH 6 and one hundred times that of pH 7. Quoting a pH difference as if it were linear understates the chemistry by orders of magnitude.

This converter does the exponentiation for you: enter a pH and read [H⁺] directly, or enter a concentration to recover the pH. It is exact arithmetic on the definition, with no approximation.

Units of hydrogen-ion concentration

Mol/L (M) is the SI concentration; mmol/L is convenient for the very small numbers pH produces; g/L expresses the same amount of H⁺ as mass, useful when a mass balance is being struck. All three describe the same ion, just in different units.

Complete conversion reference

Convert 1 unit to	pH	mol/L [H⁺]	mmol/L [H⁺]	g/L [H⁺]
1 pH	1	0.1	100	0.1008
1 mol/L [H⁺]	0	1	1000	1.008
1 mmol/L [H⁺]	3	0.001	1	0.001008
1 g/L [H⁺]	0.00346053	0.992063	992.063	1

Instruments for this measurement

PH100

Pen-type waterproof pH meter

Rapid field micro-samples

PH200

pH / ORP tester

Pen form · field & lab

PH600

Benchtop pH / ORP tester

Lab precision

PH6000C

144×144 panel pH / ORP monitor

Continuous online

pH meter principle & calibration guide

Electrode care & calibration

Two-point / three-point

Models shown are representative families, not a complete catalogue. Send us your application, water analysis and installation constraints and we will match instruments to it.

Frequently asked

How do I convert pH to concentration?

[H⁺] in mol/L = 10^(−pH). So pH 7 gives 1×10⁻⁷ mol/L and pH 4 gives 1×10⁻⁴ mol/L. The converter shows mol/L, mmol/L and g/L for any pH you enter.

Is pH 7 really neutral?

In pure water at 25 °C, yes — [H⁺] = [OH⁻] = 1×10⁻⁷ mol/L. At other temperatures neutrality shifts slightly because the ion-product of water changes, but the converter reports concentration exactly from the pH you give.

Why is pH 6 ten times more acidic than pH 7?

Because pH is a base-10 logarithm of concentration. Each unit is a factor of ten, so pH 6 has 10× the H⁺ of pH 7. This is why a one-unit change in pH is chemically large, not small.

What is 1 mol/L of H⁺ in pH?

pH = −log₁₀(1) = 0. A strong acid at 1 mol/L H⁺ reads pH 0; dilute it to 1×10⁻⁴ mol/L and the pH becomes 4.

This page performs exact unit arithmetic with no physical assumption beyond the stated reference (for example mH₂O assumes water near 4 °C, and pH follows its logarithmic definition). It is a working aid, not a substitute for the measurement method named in your permit.