pH converter
Convert pH to the actual concentration of hydrogen ions and back. Each whole step of pH is a tenfold change.
That's about the acidity of pure water. Neutral, near pure water and blood.
What it means
How acidic is that?
Values are for water at 25 °C. The neutral point shifts slightly with temperature: it is 6.14 in water at 100 °C.
Every unit
Your acidity in every unit
Learn
Three things worth knowing
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One step is ten times
Lemon juice at pH 2 is not "three times" more acidic than coffee at pH 5 — it is a thousand times.
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Sørensen and the brewery
Søren Sørensen invented the pH scale in 1909 at the Carlsberg laboratory, working on how acidity affects brewing.
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pH can go below 0
The 0 to 14 range is a convenience, not a limit. Concentrated acids reach negative pH, and strong bases go past 14.
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Background
About pH
pH is the negative base-ten logarithm of the hydrogen ion concentration. At pH 7 there are 10⁻⁷ moles of H⁺ per liter, which is neutral. Each step down multiplies the acidity by ten.