CalcaTools

Combined Gas Calculator | Final pressure from P, V & T

Solve combined gas law problems — final pressure, volume or temperature — from the other five values, with temperatures converted to kelvin automatically. The P₁V₁/T₁ = P₂V₂/T₂ relationship is applied with every step shown.

Last updated: June 2026 · Free · No sign-up required

Results

Enter values above and click Calculate to see your result instantly.

What the Combined Gas Calculator does

Under the hood, this calculator applies P₂ = P₁ × V₁ × T₂ ÷ (T₁ × V₂), temperatures in kelvin, so the combined gas law calculator result you see is genuine math, not a lookup table.

If you are new to combined gas law calculator, start with the worked example in the methodology section below — it walks the formula end-to-end with real numbers — then use the quick-reference table for common scenarios.

Quick reference

Held constantLawRelationship
TemperatureBoyleP₁V₁ = P₂V₂
PressureCharlesV₁÷T₁ = V₂÷T₂
VolumeGay-LussacP₁÷T₁ = P₂÷T₂
NothingCombinedP₁V₁÷T₁ = P₂V₂÷T₂

info Combined Gas Calculator

Free math calculator — enter your numbers and get an instant, accurate result.

info Private by design

Everything runs locally in your browser. No uploads, no accounts, no tracking.

info Works everywhere

Fully responsive and mobile-friendly — calculate on any device, any time.

info Educational

Includes the formula and step-by-step explanation so you understand the math, not just the answer.

Interpretation guide

ChangeEffect on P₂
Volume halvedPressure doubles (T fixed)
Temperature upPressure rises (V fixed)
Both V↓ and T↑Effects multiply

lightbulb Worked example

Let's say you are using the Combined Gas Calculator. Calculates combined gas law using P₂ = P₁ × V₁ × T₂ ÷ (T₁ × V₂), temperatures in kelvin, right in your browser. Enter the values that match your situation into the input fields and press calculate — using realistic numbers makes the result directly useful for you.

Result: The calculator instantly applies the formula P₂ = P₁ × V₁ × T₂ ÷ (T₁ × V₂), temperatures in kelvin and returns the result with appropriate precision.

What this means: Read the result in the context of what you are measuring. The step-by-step breakdown lets you confirm the math and understand which input most affects the outcome.

Formula & methodology

Formula: P₂ = P₁ × V₁ × T₂ ÷ (T₁ × V₂), temperatures in kelvin

The Combined Gas Calculator is built on a well-established calculation method. It uses the formula P₂ = P₁ × V₁ × T₂ ÷ (T₁ × V₂), temperatures in kelvin to turn your inputs into a reliable result. Calculates combined gas law using P₂ = P₁ × V₁ × T₂ ÷ (T₁ × V₂), temperatures in kelvin, right in your browser. The steps are shown on the page so you can follow the reasoning from input to output.

  1. Enter the initial pressure, volume and temperature (kelvin: °C + 273.15).
  2. Enter the final volume and temperature.
  3. The tool rearranges P₁V₁÷T₁ = P₂V₂÷T₂ to P₂ = P₁V₁T₂÷(T₁V₂) and verifies both sides match.

Example: P₁ = 1 atm, V₁ = 2 L, T₁ = 300 K, compressed to 1 L at 350 K → P₂ = 2.333 atm.

Authoritative source: Wolfram MathWorld

Frequently asked questions

What is the combined gas law?
It combines Boyle's, Charles's, and Gay-Lussac's laws into one relationship for a fixed amount of gas: P₁V₁/T₁ = P₂V₂/T₂. Solve for the final pressure with P₂ = P₁ × V₁ × T₂ ÷ (T₁ × V₂), always using temperatures in kelvin. For example, compressing a gas to half its volume while doubling its temperature quadruples the pressure.
Why must temperature be in kelvin?
The Combined Gas Calculator is free, private, and accurate: it runs entirely in your browser (no uploads, no accounts), applies the standard calculation, and explains each step so you can verify the result. Calculates combined gas law using P₂ = P₁ × V₁ × T₂ ÷ (T₁ × V₂), temperatures in kelvin, right in your browser. There is no limit on usage, and it works on any device.
What units do pressure and volume need?
The Combined Gas Calculator is a free online tool that calculates combined gas law using p₂ = p₁ × v₁ × t₂ ÷ (t₁ × v₂), temperatures in kelvin, right in your browser. You enter a few values, and it returns an accurate result together with a step-by-step explanation, so it works as both a calculator and a quick reference for the underlying concept.
How is this different from the ideal gas law?
The combined gas law P₁V₁/T₁ = P₂V₂/T₂ describes how a FIXED amount of gas changes between two states, and it is a special case of the ideal gas law PV = nRT with n and R constant. The ideal gas law is more general — it also solves for the amount of gas or absolute state variables. The combined law is the practical tool for compression and expansion problems.
What if my gas amount changes?
The combined gas law assumes a constant amount of gas; if gas is added or removed, you must include the mole count using the full ideal gas law PV = nRT. When the amount changes, compare states with P₁V₁/(n₁T₁) = P₂V₂/(n₂T₂). The calculator flags this assumption and reminds you to use the ideal gas law for open systems.
What does the Combined Gas Calculator do?
Calculates combined gas law using P₂ = P₁ × V₁ × T₂ ÷ (T₁ × V₂), temperatures in kelvin, right in your browser. The calculator takes your inputs, applies the standard calculation, and returns a clear result so you can make an informed decision without doing the math by hand.
What formula does the Combined Gas Calculator use?
It applies P₂ = P₁ × V₁ × T₂ ÷ (T₁ × V₂) with temperatures in kelvin, derived from the combined gas law P₁V₁/T₁ = P₂V₂/T₂. Enter the initial pressure, volume, and temperature plus any two of the final values, and the tool solves for the unknown. Remember to convert Celsius to kelvin by adding 273.15.
Is the Combined Gas Calculator free and private?
Yes — the Combined Gas Calculator. There is no sign-up, no paywall, no trial, and no limit on how many calculations you can run. CalcaTools covers its costs with non-intrusive display advertising, so the calculator itself never asks for payment or restricts any feature.
How accurate is the Combined Gas Calculator?
The Combined Gas Calculator applies the standard formula: P₂ = P₁ × V₁ × T₂ ÷ (T₁ × V₂), temperatures in kelvin. It is tested against published worked examples before launch and uses native double-precision arithmetic, so results are accurate to typical precision for the values you enter — with no intermediate rounding that could distort the answer.

Explore the full math toolkit

Every CalcaTools math calculator — algebra, geometry, trigonometry, statistics, sequences, and unit conversions — with step-by-step workings on every result.