Ksp Solubility Calculator
Convert between the solubility product constant (Ksp) and molar solubility for a sparingly soluble salt of any AxBy formula.
Solve for
Maximum amount of salt that dissolves per litre
- 1
Denominator x^x × y^y
1^1 × 1^1 = 1 - 2
Total ion exponent n = x + y
1 + 1 = 2 - 3
Ksp ÷ (x^x × y^y)
1.8000e-10 ÷ 1 = 1.8000e-10 - 4
Molar solubility s = (...)^(1÷n)
1.8000e-10^(1÷2) = 0.000013Taking the nth root gives the equilibrium molar solubility of the salt.
How does this calculator work?
For a salt AxBy ⇌ xA + yB, Ksp = (x·s)^x·(y·s)^y. Given Ksp, molar solubility is s = (Ksp / (x^x·y^y))^(1/(x+y)); ion concentrations are x·s and y·s. Reverse the mode to compute Ksp from a measured solubility. Assumes pure water at 25 °C with ideal behaviour.
Formula
How this is calculated
A sparingly soluble salt AxBy dissolves according to the equilibrium AxBy ⇌ x A + y B. If s is the molar solubility (moles of formula units dissolved per litre), then at saturation [A] = x·s and [B] = y·s. Substituting into the equilibrium expression gives Ksp = (x·s)^x · (y·s)^y = x^x · y^y · s^(x+y).
When you provide Ksp and the stoichiometric coefficients x and y, the tool inverts this relation to solve for the molar solubility: s = (Ksp / (x^x · y^y))^(1/(x+y)). It then reports the individual ion concentrations [cation] = x·s and [anion] = y·s. Switching the mode lets you supply the measured solubility instead and computes the resulting Ksp directly from (x·s)^x · (y·s)^y.
The model assumes a pure aqueous system at 25 °C with no common-ion effect, no complex-ion formation, and ideal (activity ≈ concentration) behaviour, so it is most accurate for dilute, simple salts. x and y must be positive integers; Ksp and solubility must be positive. All concentrations are in mol/L.
Frequently asked questions
Molar solubility is the number of moles of a solid salt that dissolve to form a saturated solution per litre of water (mol/L). It differs from solubility expressed in grams per litre, which you get by multiplying by the molar mass.
Each ion appears in the equilibrium expression raised to its stoichiometric coefficient. Because [A] = x·s and [B] = y·s, the Ksp expression becomes (x·s)^x · (y·s)^y, which simplifies to x^x · y^y · s^(x+y).
No. This calculator assumes the salt dissolves in pure water. Adding a common ion suppresses solubility, which requires solving the equilibrium with the extra initial ion concentration included.
Also known as
TG we-Calculate Editorial Team. (2026). Ksp Solubility Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/ksp-solubility-calculator
TG we-Calculate Editorial Team. "Ksp Solubility Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/ksp-solubility-calculator.
TG we-Calculate Editorial Team, "Ksp Solubility Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/ksp-solubility-calculator
@misc{wecalculate_ksp_solubility_calculator, title = {Ksp Solubility Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/ksp-solubility-calculator}}, year = {2026}, note = {TG we-Calculate} }
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