How to use the first law of thermodynamics calculator
Find change in internal energy from heat and work. Enter heat added to system, work done by system in the fields above; the change in internal energy is computed instantly and plotted on the chart so you can see how the answer changes.
Formula
Variables
- Q — Heat added to system (J)
- W — Work done by system (J)
Worked example
With heat added to system = 800 J, work done by system = 300 J, the calculator gives change in internal energy ≈ 500 J.
Frequently asked questions
What is the formula for the first law of thermodynamics calculation?
Change in internal energy (J) = Q-W. Here Q is heat added to system (J), W is work done by system (J).
What inputs do I need for the first law of thermodynamics calculator?
You need heat added to system in J, work done by system in J. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use this calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.