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Ideal gas law calculator

Compute the pressure of a gas from moles, temperature and volume (PV = nRT).

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The Ideal gas law calculator turns Moles (n), Temperature (K), Volume (L) into Pressure (atm), instantly and for free. For instance, with Moles (n) = 1, Temperature (K) = 300 and Volume (L) = 24.5 it returns Pressure (atm) = 1.005.

How to use it

  1. Enter your values: Moles (n), Temperature (K), Volume (L).
  2. Read the result instantly: Pressure (atm).

Frequently asked questions

What does the Ideal gas law calculator actually compute?

It takes Moles (n), Temperature (K) and Volume (L) and derives Pressure (atm) from them. The calculation is live as you type, so the result updates on every change.

What information do I need to provide?

3 values: Moles (n), Temperature (K) and Volume (L). Nothing else is required — no account, no file upload.

Can you show a worked example?

With Moles (n) = 1, Temperature (K) = 300 and Volume (L) = 24.5, the calculator returns Pressure (atm) = 1.005. Those figures come from running this exact tool, so you can reproduce them by entering the same values.

What happens if I enter larger values?

It moves a lot. Using Moles (n) = 2, Temperature (K) = 600 and Volume (L) = 27 instead, Pressure (atm) goes from 1.005 to 3.647 — which is why it is worth testing a few scenarios rather than trusting a single figure.

What does it give for smaller values?

Scaled down to Moles (n) = 0.5, Temperature (K) = 150 and Volume (L) = 22.1, Pressure (atm) comes out at 0.278. The relationship is worth checking at both ends before you rely on a single result.

When would I actually use this?

Preparing a solution at a stated concentration, working out how much of a reagent a reaction needs, and converting between mass, moles and volume.

What is the most common mistake?

Confusing molarity with molality. One is per litre of solution and the other per kilogram of solvent; they diverge as concentration rises, and only one of them is temperature-independent.

What is the difference between the Ideal gas law calculator and the Beer-Lambert law calculator?

This one returns Pressure (atm); the Beer-Lambert law calculator returns Result and Unit of result. That is the whole difference — open the one whose figure you need.

Is there a tool for the next step?

Molarity calculator is the closest one after this: Compute the molar concentration of a solution from moles and volume.

What else is worth having open alongside it?

Coulomb's Law Calculator and Hooke's law calculator — they come up in the same task often enough to be worth a second tab.

Further reading

All guides →
ExplainerThe Ideal Gas Law Explained: PV = nRT, R in Every Unit, and Where It BreaksPV = nRT holds when the gas is dilute and far from condensing. The value of R depends entirely on the units you feed it, and the temperature is never in degrees Celsius.ExplainerOsmotic Pressure Counts Particles, Not Molecules0.15 M of a salt that splits in two and 0.30 M of one that does not give the identical 7.64 atmospheres. Only the particle count reaches the membrane.ExplainerA Party Balloon Lifts Fourteen Grams, Not Its Own VolumeA 28 cm latex balloon nets 14 g of lift, so a kilogram takes 72 of them. At 2,000 metres the same balloon lifts 21 % less and you need 91.ExplainerAn Absorbance of Two Means One Per Cent of the Light Gets Through6,220 M⁻¹cm⁻¹ at 100 µM through 1 cm gives A = 0.622, and 23.9 % of the light emerges. Double the path length and A doubles to 1.244 — the scale is logarithmic, and that is where it breaks.ExplainerSalting Pasta Water Raises the Boiling Point by Two Tenths of a DegreeFifty grams of salt in five litres is 0.171 mol/kg and buys +0.175 °C. Reaching a full degree would take 285 grams — most of a box.ExplainerThe Same Burette Reading Gives Two Different Concentrations24.80 mL of 0.1 M titrant into 25.00 mL of analyte gives 0.0992 M — or 0.0496 M if the analyte releases two protons. The stoichiometry is typed, not measured.