Unit Converters · Free tool
pH Calculator
Convert between pH, pOH, [H⁺], and [OH⁻] at 25°C in one click. Color spectrum shows acidic, neutral, or basic instantly. Free, browser-only, no sign-up.
pH
7.00
pOH
7.00
[H⁺]
1.000 × 10⁻⁷
[OH⁻]
1.000 × 10⁻⁷
Quick reference
- pH 1 stomach acid · battery acid
- pH 4 tomato juice · acid rain
- pH 7 pure water at 25°C (neutral)
- pH 8.4 seawater · baking soda solution
- pH 11 ammonia · soapy water
- pH 13–14 bleach · drain cleaner
Note: pH + pOH = 14 only at 25°C. At higher temperatures water's Kw increases and neutral pH shifts below 7.
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What it does
Convert between pH, pOH, [H⁺], and [OH⁻] at 25°C. The pH spectrum visualization shows where your solution sits on the acid-to-base scale. Useful for acid-base titrations, buffer prep, and chemistry homework.
pH = −log₁₀[H⁺]. At 25°C, pH + pOH = 14 (this shifts at other temperatures — disclosed in the reference panel).
Embed this tool on your siteShow snippetHide
Paste this snippet into any page. Loads on-demand (lazy), no tracking scripts, and sized to most dashboards. Replace the height to fit your layout.
<iframe src="https://freetoolarena.com/embed/ph-calculator" width="100%" height="720" frameborder="0" loading="lazy" title="pH Calculator" style="border:1px solid #e2e8f0;border-radius:12px;max-width:720px;"></iframe>How to use it
- Pick what you know (pH, pOH, [H⁺], or [OH⁻]).
- Enter the value.
- Read pH, pOH, [H⁺], and [OH⁻] together — plus where it sits on the colored scale.
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