Aisha K.
Mar 12, 2026
Clean layout and the results update instantly. Exactly what I needed for a quick planning check.
Unit Converters
pH to Hydrogen Ion Concentration Converter
[H⁺] = 10^(−pH) mol L⁻¹. pOH ≈ 14 − pH at 25 °C.
[H⁺] = 10^(−pH) mol/L as a dilute-water approximation. pH 7 is 1×10⁻⁷ M. Strong acids, high ionic strength, and 37 °C blood chemistry all argue with that textbook line. Use activity if you are publishing.
pH
pH → mol/L
1.0000e-7 mol/L
pH 7 is 10⁻⁷ mol/L. Activity is not concentration in a strong brine.
- pH
- 7
- pOH (25 °C)
- 7
Plain-English guide
Terms & how it works
Confused by a field? Read the short definitions here while you use the tool.
pH
The “pH” value used in this tool’s formula. Adjust it to see results update live.
How this calculator works
[H⁺] = 10^(−pH) mol/L as a dilute-water approximation. pH 7 is 1×10⁻⁷ M. Strong acids, high ionic strength, and 37 °C blood chemistry all argue with that textbook line. Use activity if you are publishing. [H⁺] = 10^(−pH) mol L⁻¹. pOH ≈ 14 − pH at 25 °C. Example: pH 3 → 0.001 mol/L. pH 7 → 1×10⁻⁷ mol/L.
[H⁺] = 10^(−pH) mol L⁻¹. pOH ≈ 14 − pH at 25 °C.
Example: pH 3 → 0.001 mol/L. pH 7 → 1×10⁻⁷ mol/L.
When to use this pH to [H+]
Common use cases
- [H⁺] = 10^(−pH) mol/L as a dilute-water approximation. pH 7 is 1×10⁻⁷ M. Strong acids, high ionic strength, and 37 °C blood chemistry all argue with that textbook line. Use activity if you are publishing.
- Sanity-check with this case: pH 3 → 0.001 mol/L. pH 7 → 1×10⁻⁷ mol/L.
- The relationship is: [H⁺] = 10^(−pH) mol L⁻¹. pOH ≈ 14 − pH at 25 °C.
Localized examples
- Unit Converters: the example on this page uses the same formula as the widget.
What you get
- Fields: pH
- [H⁺] = 10^(−pH) mol L⁻¹. pOH ≈ 14 − pH at 25 °C.
- Example on the page: pH 3 → 0.001 mol/L. pH 7 → 1×10⁻⁷ mol/L.
How to Convert pH to [H+] Step-by-Step
- 1Enter pH. Use the values you have, not a catalog average, unless that is all you know.
- 2[H⁺] = 10^(−pH) mol L⁻¹. pOH ≈ 14 − pH at 25 °C.
- 3Worked case: pH 3 → 0.001 mol/L. pH 7 → 1×10⁻⁷ mol/L.
- 4Check which dictionary the other person is using — US or UK, decimal or 1,024 — then trust the number.
Governing formula
[H⁺] = 10^(−pH) mol L⁻¹. pOH ≈ 14 − pH at 25 °C.
pH 3 → 0.001 mol/L. pH 7 → 1×10⁻⁷ mol/L.
Example: set pH = 7, then read the result.
Variable definitions
- value
pH
The “pH” field. Default 7; typical range -2–16.
- The conversion ([H⁺] = 10^(−pH) mol L⁻¹. pOH ≈ 14 − pH at 25 °C.) does not pick US vs UK gallons, SI vs binary megabytes, or Mach at altitude for you. Read the footnote on the page.
- Nothing here is uploaded for the calculation itself.
Frequently Asked Questions
Possible in very concentrated acid. The log still works; the activity coefficient will not be 1.
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Reviews & Ratings
See what others think about this tool, then leave your own rating to help improve CalculioHub.
4.8
out of 5.0
4 reviews
Daniel R.
Feb 28, 2026
Very usable on mobile. Would love a save/export option later, but the math feels solid.
Priya S.
Feb 3, 2026
The FAQ section answered my questions before I even had to search. Smooth dark mode too.
Marcus L.
Jan 19, 2026
Simple inputs, clear outputs. This replaced three bookmarks I used to juggle.
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