Partial Pressure Calculator — Pᵢ = XᵢP

Dalton's law: each gas in a mixture pushes as if the others weren't there, contributing its mole fraction of the total pressure. Enter the moles of the gas of interest, total moles, and total pressure.

Partial Pressure Calculator — Pᵢ = XᵢP

$P_i = X_i P_{total}$

Solve for

Moles of this gas (n_i)

Unit

Total moles in mixture (n_tot)

Unit

Total pressure (P_tot)

Unit

Result unit

How to interpret the result

Worked check: 0.25 mol O₂ in 1.00 mol of air at 1.00 atm → P(O₂) = 0.25 × 1.00 = 0.250 atm. Partial pressures always sum to the total.

Assumptions

Ideal-gas mixture (Dalton's law holds)
Gases do not react with each other