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Gay Lussac Law Calculator

Work out gay lussac law instantly with clear inputs, formula shown and shareable results.

About Gay Lussac Law Calculator

At constant volume, pressure is proportional to absolute temperature: P1/T1 = P2/T2. Heating a sealed vessel from 300 K to 450 K raises 200 kPa to 300 kPa. The law only works in kelvin - using Celsius would make the ratio meaningless and is the classic exam mistake.

Formulas

Gay-Lussac's law

P1 / T1 = P2 / T2 at constant volume

Final pressure

P2 = P1 x T2 / T1

Worked example

With the default values below, Gay Lussac Law Calculator returns Final Pressure of 300.000. Change any input above and every figure here is recalculated in your browser.

Inputs used

Initial pressureminimum 0 kPa
200 kPa
Initial temperatureminimum 0 K
300 K
Final temperatureminimum 0 K
450 K

Results

Final Pressure
300.000 kPa
Change In Pressure
100.000 kPa
Temperature Ratio
1.5000
Percentage Pressure Change
50.00%

Step by step

  1. 1Values used
  2. 2Gay-Lussac's law
  3. 3Final pressure
  4. 4Final Pressure= 300.000 kPa
  5. 5Change In Pressure= 100.000 kPa
  6. 6Temperature Ratio= 1.5000
  7. 7Percentage Pressure Change= 50.00

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why must temperature be absolute?

Because pressure vanishes only at absolute zero, so the proportionality is anchored there. Celsius has an arbitrary zero and gives nonsense ratios.

Is this why aerosol cans warn against heat?

Exactly. A can at 200 kPa gauge on a 20 C day reaches well over 300 kPa in a hot car, and the wall stress rises with it.

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Gay Lussac Law Calculator – Calculate Final Pressure