Boiling Point Elevation Calculator
Enter the molality, the van 't Hoff factor, and the solvent (or a custom ebullioscopic constant Kb) to find the boiling-point elevation. Optionally get the estimated boiling point of the solution. The equation is an idealized dilute-solution model.
Last updated: September 26, 2026
Frequently asked questions
What is boiling-point elevation?
It is the increase in a solvent's boiling temperature when a nonvolatile solute is dissolved in it. Dissolved particles lower the solvent's vapor pressure, so a higher temperature is needed to boil.
What is the formula?
ΔTb = i × Kb × m, where i is the van 't Hoff factor, Kb is the solvent's ebullioscopic constant in K·kg/mol, and m is the molality in mol/kg.
What is the difference between molality and molarity?
Molality is moles of solute per kilogram of solvent. Molarity is moles per liter of solution. The equation uses molality.
What van 't Hoff factor should I use?
It is about 1 for molecules that do not dissociate, such as sugar, and close to 2 for a fully dissociated salt such as NaCl. Real solutions deviate from these ideal values.
Why is Kb different for each solvent?
Kb depends on the solvent's properties. That is why the calculator offers solvent presets and a custom option instead of a single constant for everything.
When does the equation fail?
For concentrated, strongly interacting, or volatile-solute solutions. It is an idealized dilute-solution model.