Calculate gas pressure from temperature and volume. Choose units, include compressibility, and see clear steps. Export results for study, experiments, and practical engineering decisions.
| Case | n (mol) | T (K) | V (L) | Z | Pressure (atm) | Pressure (kPa) |
|---|---|---|---|---|---|---|
| Standard molar volume | 1.0 | 298.15 | 24.465 | 1.00 | 1.000 | 101.325 |
| Smaller container | 1.0 | 300 | 10.0 | 1.00 | 2.462 | 249.4 |
| Real-gas correction | 2.0 | 350 | 20.0 | 0.90 | 2.588 | 262.2 |
These examples assume ideal behavior unless Z modifies it.
The ideal gas relationship connects pressure, volume, temperature, and amount of substance:
P·V = n·R·T
Solving for pressure and optionally including a compressibility factor gives:
P = Z · n · R · T / V
For high pressures, very low temperatures, or near condensation, the ideal model may deviate. Use Z carefully or a real-gas equation when needed.
The ideal gas law links microscopic motion to macroscopic pressure. At a fixed amount of gas, raising absolute temperature increases molecular kinetic energy and collision rate, so pressure rises in direct proportion to T. At fixed temperature, shrinking volume forces more collisions per area, so pressure increases as 1/V.
This tool computes pressure from n (moles), T (temperature), and V (volume). You can enter the amount as moles directly or convert from mass using n = m/M. Internally, the calculator converts temperature to Kelvin and volume to cubic meters to keep units consistent.
Results are shown in Pa, kPa, MPa, bar, atm, torr, and psi. Useful reference points include 1 atm = 101.325 kPa, 1 bar = 100 kPa, and 1 torr ≈ 133.322 Pa. These conversions help compare vacuum work, atmospheric testing, and mechanical gauge readings in one view.
In classroom and lab settings, volumes often range from 10 mL syringes to 50 L vessels, while temperatures span roughly 273–400 K. For example, 1 mol at 298.15 K occupying 24.465 L gives about 1 atm, matching common molar volume conditions near room temperature.
The optional Z factor scales pressure to approximate non-ideal behavior. When Z < 1, attractions reduce pressure relative to ideal predictions; when Z > 1, repulsions increase it. For moderate pressures, using Z values from charts or process data can significantly improve estimates.
Because P = Z·n·R·T/V, small errors in temperature or moles transfer linearly to pressure, while
volume errors are amplified inversely. A 2% underestimate in volume typically causes about a 2% overestimate in pressure,
making careful volume measurement important for tight tolerances.
The steps panel shows how each input is converted and how the pressure is formed in base units before conversions. This is helpful for reports, audits, and lab notebooks where you need to document assumptions, constants, and unit handling without rewriting the full derivation each time.
The ideal model can drift near phase change, at very high pressures, or at cryogenic temperatures. If results look inconsistent with sensors, validate inputs, apply an appropriate Z value, or consider a real-gas model. This calculator is best for fast checks, comparisons, and early-stage sizing decisions.
It computes gas pressure from the ideal gas relationship using moles (or mass and molar mass), temperature, volume, and an optional compressibility factor Z.
Kelvin is an absolute scale. The ideal gas law uses absolute temperature, so Celsius or Fahrenheit must be converted to Kelvin to avoid incorrect proportional scaling.
Use Z when pressures are moderate to high, temperatures are far from ambient, or process data indicates non-ideal behavior. Z values often come from charts, EOS software, or plant measurements.
Yes. Select the mass mode and provide mass and molar mass. The calculator converts to moles using n = m/M before applying the pressure formula.
Use Pa or kPa for scientific work, bar for industrial process discussions, atm for chemistry comparisons, torr for vacuum contexts, and psi for many mechanical gauges.
Pressure is most sensitive to volume because it appears in the denominator. Small volume errors directly create similar percentage errors in pressure, so measure volume carefully.
Differences can come from non-ideal behavior, wet gas, leaks, temperature gradients, or unit mistakes. Verify absolute temperature, volume units, and Z. Use a real-gas model if conditions are extreme.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.