Chemistry Unit Converter
Convert chemistry units across ten categories: temperature, pressure, energy, mass, volume, concentration and more. Shows the formula for each conversion.
What this calculator does
Choose a category, enter a value and a unit, and see it in every other unit of that category with the conversion formula next to each result.
When you need it
Chemistry problems mix units all the time: kelvin and Celsius, atm and mmHg, joules and calories. Converting before you substitute avoids the most common source of wrong answers.
Formulas
- K = °C + 273.15
- °F = °C × 9/5 + 32
- 1 atm = 101 325 Pa = 760 mmHg = 1.01325 bar
- 1 cal = 4.184 J
How to use it
- Choose the category, for example temperature or pressure.
- Enter the value and select the unit you start with.
- Read the same quantity in every other unit, with its formula.
Worked example
Express 25 °C in kelvin and in degrees Fahrenheit.
- K = 25 + 273.15 = 298.15 K
- °F = 25 × 9/5 + 32 = 77 °F
Answer
25 °C is 298.15 K and 77 °F.
Common mistakes
- Adding 273 to a temperature difference: a change of 10 °C is a change of 10 K.
- Using the wrong calorie: 1 cal is 4.184 J, while a food Calorie is 1 kcal.
- Rounding too early in a multi-step conversion.
Related tools
Frequently asked questions
How do I convert atm to mmHg?
Multiply by 760. One atmosphere equals 760 mmHg.
How do I convert Celsius to kelvin?
Add 273.15 to the Celsius value.
How many joules are in a calorie?
One thermochemical calorie is 4.184 joules.