Case 1
- Initial volume V₁
- 1
- Initial temperature T₁
- 273.15K
- Final temperature T₂
- 373.15K
1.3661
Open with these valuesCharles's Law Calculator
1.3661unit of V₁
Result: 1.3661 unit of V₁At constant pressure a gas expands in proportion to its absolute temperature: double the kelvin, double the volume. Enter the starting volume and both temperatures in kelvin. A balloon taken from 0 °C to 100 °C grows by 37 %, not by a factor of a hundred.
The numbers at a glance
Held fixed: Initial volume V₁ 1.000, Initial temperature T₁ 273.15 K.
| Final temperature T₂ (K) | Result |
|---|---|
| 100.00 | 0.3661 |
| 200.00 | 0.7322 |
| 300.00 | 1.0983 |
| 373.15Your value | 1.3661 |
| 400.00 | 1.4644 |
| 500.00 | 1.8305 |
| 600.00 | 2.1966 |
| 700.00 | 2.5627 |
Worked examples
Case 2
- Initial volume V₁
- 10
- Initial temperature T₁
- 290K
- Final temperature T₂
- 310K
10.6897
Open with these valuesCase 3
- Initial volume V₁
- 22.4
- Initial temperature T₁
- 273.15K
- Final temperature T₂
- 298.15K
24.4502
Open with these valuesHow it's calculated
V₂ = V₁ × T₂ ÷ T₁
- StepEnter the starting volume in any unit you like.
- StepConvert both temperatures to kelvin: degrees Celsius plus 273.15.
- ResultRead the final volume in the unit you used for the first one.
What this number means
Kelvin is compulsory here
The volume is proportional to the absolute temperature, so the scale has to start at true zero. Entering 17 and 37 instead of 290 K and 310 K turns a volume of 10 into 21.76 rather than 10.69.
The pressure has to stay put
The law describes a gas free to expand against a fixed pressure — the balloon carried into a warm room. If the pressure moves as well, the combined gas law is the one to reach for.
The volume may be in any unit
Only the temperature ratio scales it, so litres, millilitres and cubic metres all work. The answer comes back in the unit of V₁.
Commonly misread
0 °C to 100 °C ought to multiply the volume by a hundred.
In kelvin it is 373.15 divided by 273.15, so the volume grows by 37 %. Celsius has no true zero to divide by.
The pressure rises as the gas is warmed.
Charles's law assumes a fixed pressure throughout. With two quantities moving, the combined gas law is needed.
A balloon that swells in a warm room has gained gas.
The amount of substance is unchanged; only the volume grows. From 4 °C to 22 °C that is 295.15 over 277.15, about 6.5 % more.
Reference table
| V₁, T₁, T₂ | Temperature change | Final volume V₂ |
|---|---|---|
| 1, 273.15, 273.15 | none | 1.0000 |
| 1, 273.15, 373.15 | 0 °C to 100 °C | 1.3661 |
| 0.5, 250, 500 | doubled | 1.0000 |
| 2, 300, 600 | doubled | 4.0000 |
| 10, 290, 310 | 17 °C to 37 °C | 10.6897 |
| 22.4, 273.15, 298.15 | 0 °C to 25 °C | 24.4502 |
Questions
What is Charles's law?
For a fixed amount of gas at constant pressure, volume is proportional to absolute temperature. Written as a ratio it says V₁ divided by T₁ equals V₂ divided by T₂.
Why must temperatures be in kelvin?
Because the law is about a ratio, and a ratio needs a scale that starts at true zero. Using Celsius makes a change from 0 °C to 100 °C look infinite instead of a rise of 37 %.
How much does a balloon grow in a warm room?
From a fridge at 4 °C to a room at 22 °C the volume rises by about 6.5 %, since 295.15 divided by 277.15 is 1.065. The balloon looks fuller but has not gained any gas.
What if the pressure changes as well?
Charles's law then no longer holds on its own. Use the combined gas law, which carries the pressure ratio alongside the temperature ratio.
Sources and last check
Information, not professional advice.