Solubility Product (Ksp) Calculator

Molar solubility from Ksp, for any salt stoichiometry.

Written and maintained by Mohit PatelLast checked August 4, 2026How we build these

Ksp

Scientific notation works — AgCl is 1.8e-10, CaF₂ is 3.9e-11.

Cations per formula unit

AgCl is 1 and 1. CaF₂ is 1 and 2. Ag₂CrO₄ is 2 and 1.

Anions per formula unit

Molar solubility

1.342e-5 M

Ksp = (1s)^1 · (1s)^1

Molar solubility (s)1.3416e-5 mol/L

Cation concentration1.3416e-5 M

Anion concentration1.3416e-5 M

Ksp expressionKsp = (1s)^1 · (1s)^1

Ksp1.8000e-10

Ksp values only rank solubility within the same formula type. CaF₂ has a smaller Ksp than AgCl, 3.9 × 10⁻¹¹ against 1.8 × 10⁻¹⁰, yet it is about sixteen times more soluble, because the fluoride term is squared and that changes how the root works out. Comparing Ksp across different stoichiometries is one of the most common errors in the topic. Convert to molar solubility first, then compare.

How the Solubility Product (Ksp) Calculator works

Enter a Ksp and the ion counts in the formula and this returns the molar solubility along with each ion's concentration at saturation. It handles 1:1, 1:2, 2:1 and larger stoichiometries, which is where most Ksp mistakes actually happen.

Also known as: ksp calculator · molar solubility calculator · ksp to solubility converter · solubility product constant

Where to go next

The Solubility Product (Ksp) question rarely arrives on its own. These are the ones that usually come with it:

Common Ion Effect Calculator — How far a shared ion suppresses solubility.
Reaction Quotient Calculator — Compare Q to K and see which way a reaction runs.
Molarity Calculator — Moles per litre of solution — not of solvent.
Speed Distance Time Calculator — Any one of the three from the other two, in four units.

Sources

Frequently asked questions

How do I calculate molar solubility from Ksp?

Write the dissolution equation, express each ion as a multiple of s, substitute into the Ksp expression and solve. For AgCl, Ksp = s², so s = √Ksp = 1.34 × 10⁻⁵ M. For CaF₂, Ksp = 4s³.

Does a smaller Ksp always mean less soluble?

Only when comparing salts with the same formula type. CaF₂ has a smaller Ksp than AgCl yet is about sixteen times more soluble, because the exponents in the two expressions differ. Convert both to molar solubility before comparing.

Why is Ksp temperature dependent?

Because it is an equilibrium constant, and every equilibrium constant shifts with temperature. Most salts dissolve endothermically and get more soluble when heated; a few, including calcium sulfate, do the opposite.

What does it mean if Q is greater than Ksp?

The solution is supersaturated and a precipitate should form. Q below Ksp means more can dissolve, and Q equal to Ksp is exactly saturated.

Put this calculator on your own site

Free to use, on any site, commercial or not. Paste this where you want it to appear. It is a plain iframe, so it works in WordPress, Squarespace, Wix, Webflow, Ghost and anything else that accepts HTML.

The one-line version

<iframe src="https://www.thecalclibrary.com/embed/solubility-product-calculator" width="100%" height="640" style="border:1px solid #e2e8f0;border-radius:12px" loading="lazy" title="Solubility Product (Ksp) Calculator"></iframe>
<p style="font:13px/1.5 system-ui,sans-serif;margin:6px 0 0;color:#64748b">Powered by <a href="https://www.thecalclibrary.com/solubility-product-calculator" style="color:#64748b">Solubility Product (Ksp) Calculator</a> from The Calc Library</p>

The only condition is that the credit line below the frame stays in place. That one line is what pays for the tool being free — it is how anyone else finds it.