Worked example

Use to find new V after T&P change.

Combined Gas Law

Combine Boyle, Charles, Gay-Lussac for constant n.

Equation

$\frac{P_1 V_1}{T_1}=\frac{P_2 V_2}{T_2}$

Inline: $\frac{P_1 V_1}{T_1}=\frac{P_2 V_2}{T_2}$$

Variables

Symbol	Quantity	Unit	Notes
$P$	pressure	atm	—
$V$	volume	L	—
$T$	temperature	K	—

Conditions and limitations

n constant.

Rearrangements

$T_2 = P_2 V_2 T_1 / (P_1 V_1)$

Dimensional check: atm·L/K ✓

Worked example

Use to find new V after T&P change.

Steps: write equation → substitute with units → check dimensional consistency → report with correct significant figures.

Common errors

• Mixing unit systems

Related resources

• gases-gas-laws topic
• Calculators — linked only when a real calculator implements this formula.
• Constants — sourced constants with version when values are required.

Sources

• NIST Physical Constants 2022 — CODATA.

Reviewed 2026-08-21 by Editorial Team; due 2027-08-21.