pH Calculator

Because pH isn't just a number—it's the difference between a thriving aquarium and fish soup. Calculate everything from simple acid/base solutions to complex buffer systems and titrations.

Simple pH Calculations

For when you just need a quick pH without the complications of weak acids or fancy equilibria.

Concentration of your strong acid solution

Results

Ready to Calculate pH?

Select your solution type above and enter the concentration to see the pH and other properties.

What Actually IS pH?

Everyone knows pH measures how acidic something is. Everyone also immediately forgets which end of the scale is which. Is pH 1 acidic or basic? (It's very acidic, by the way. Like, car-battery acidic.)

The weirdness starts with the name. pH means 'power of hydrogen,' which sounds like something from a sci-fi movie but actually refers to the mathematical exponent in the hydrogen ion concentration. When chemists say pH 3, they're shorthand for saying [H⁺] = 10⁻³ M, or 0.001 M.

Why the negative exponent?

Because hydrogen ion concentrations are usually tiny numbers, and scientists got tired of writing all those zeros. pH 7 is 10⁻⁷ M, which is 0.0000001 M. See? Annoying.

Here's the thing that trips everyone up: the pH scale is backwards from what your intuition expects. Lower numbers = more acidic = more hydrogen ions. Higher numbers = more basic = fewer hydrogen ions. It's inverted because of that negative exponent.

Strong vs Weak Acids: Not What You Think

Quick: which is more dangerous, a strong acid or a weak acid?

Trick question. 'Strong' and 'weak' don't mean what you think they mean in chemistry. They're not about danger or concentration—they're about personality.

Strong Acid

The chemistry equivalent of someone who can't keep a secret. Drop HCl into water, and it immediately spills everything, breaking apart completely into H⁺ and Cl⁻. Total transparency. No chill.

Weak Acid

More reserved. Acetic acid (vinegar) in water mostly stays as acetic acid. Only a tiny percentage—maybe 1-2%—actually breaks apart at any given moment. The rest just hangs out, intact.

The wild part:

You can have a concentrated weak acid that's way more dangerous than a dilute strong acid. A 10 M solution of acetic acid (glacial acetic acid) will absolutely ruin your day, even though it's 'weak.' Meanwhile, 0.001 M HCl is so dilute you could drink it. (Don't drink it.)

Important Notes

This calculator provides estimates based on simplified models. Real solutions may have additional equilibria, ionic strength effects, or temperature dependencies. For precise laboratory work, verify with experimental measurements.