Chemistry
Ionic Strength Calculator
Add up the ionic strength of a solution from the concentration and charge of each ion.
Your inputs
Change any value to update the result instantly.
Ionic strength I
0.1 mol/L
Total ion concentration
0.2 mol/L
Ion 1 contribution
0.05 mol/L
Ion 2 contribution
0.05 mol/L
Ion 3 contribution
0 mol/L
Reading
Dilute enough for the Debye-Hückel limiting law
Charge is squared, so a doubly charged ion contributes four times as much as a singly charged one at the same concentration. Set a concentration to zero to leave that ion out.
What this calculator does
Adds up the ionic strength of a solution from each ion's concentration and charge.
What your result means
Higher ionic strength means stronger electrostatic screening, which lowers ion activity.
Formula and working
I = ½ Σ cᵢ zᵢ²
- 1
Collect the inputs
Ion 1 concentration = 0.1 mol/L; Ion 1 charge = 1; Ion 2 concentration = 0.1 mol/L; Ion 2 charge = -1; Ion 3 concentration = 0 mol/L; Ion 3 charge = 2
- 2
Apply the formula
I = ½ Σ cᵢ zᵢ²
- 3
Result
Ionic strength I = 0.1 mol/L
Frequently asked questions
Symbols and assumptions
- I
- Ionic strength
- c_i
- Concentration of ion i
- z_i
- Charge number of ion i
- • Concentrations are in mol/L.
- • Complete dissociation of the salts.
Sources and review
Reviewed 2026-09-22 · Next review 2027-09-22
- • The Debye-Hückel limiting law only holds at low ionic strength, roughly below 0.01 mol/L.
Important limitation
This is an educational estimate based only on the values and formula shown. Verify current rates, rules, units, and professional standards before relying on the result. It is not personalized financial or investment advice.
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