How to use the nuclear fusion calculator
Prepare the values for this calculation
Calculate fusion Q-value from two reactant masses and the complete product rest-mass sum. Use the formula below to check that it answers your question. Read the input units before transferring figures from a statement, measurement or dataset.
Enter and check each input
- Reactant 1 mass (u): enter a value at least 1e-12. Use the unit named in the label or selected above. Do not leave this required field blank.
- Reactant 2 mass (u): enter a value at least 1e-12. Use the unit named in the label or selected above. Do not leave this required field blank.
- Complete product mass sum (u): enter a value at least 1e-12. Use the unit named in the label or selected above. Do not leave this required field blank.
- Number of fusion events: enter a value at least 1 and no more than 1e+30. Use the unit named in the label or selected above. Do not leave this required field blank.
The input table gives a complete example. Keep units and time periods consistent across related fields.
Calculate and resolve any input error
Choose Calculate after entering the values. Changes also update the answer after a short pause. If an error appears, follow its message, correct the field and calculate again. Reset restores the example values.
Interpret the answer
Check Fusion Q-value first. With the unchanged example inputs, it is 17.5893006996 MeV/event. Compare the additional metrics with the primary result; each has its own label and unit.
Compare and keep a useful result
For a controlled comparison, keep every other example input unchanged and change Reactant 1 mass (u) from 2.01410177812 to 2.215511956. The resulting Fusion Q-value is 205.2016935622 MeV/event. This illustrates the equation’s response to that input, rather than a forecast of real events.
Read the chart’s axis labels and data table. A scenario curve changes one stated input while holding the others fixed; it does not add external observations. Use Download graph to save an available chart as a PNG.
Use Copy result or Download CSV to keep the answer. Share tool shares the page address without placing your input values in the URL. Recheck inputs and assumptions before using the result for a decision.
Nuclear Fusion Calculator formula
Q=(m₁+m₂−m_products)c²=(Δm in u)×931.49410242 MeV.
Inputs and units
| Input | Format / range | Example |
|---|---|---|
| Reactant 1 mass (u) | minimum 1e-12 | 2.01410177812 |
| Reactant 2 mass (u) | minimum 1e-12 | 3.01604928199 |
| Complete product mass sum (u) | minimum 1e-12 | 5.01126817008 |
| Number of fusion events | minimum 1; maximum 1e+30 | 1 |
Worked example
Using the example inputs above, the fusion q-value is 17.5893006996 MeV/event.
- Fusion Q-value
- 17.5893006996 MeV/event
- Mass defect
- 0.01888289003 u
- Total energy for entered events
- 2.8181166589e-12 J
Results and assumptions
Rest-mass energy difference only; product mass must include every reaction product. Atomic or nuclear masses must be used consistently so electron masses cancel appropriately.
Sources and method references
Fix an input or unexpected result
Reactant 1 mass (u) is required. Enter reactant 1 mass (u) using the format and bounds in the input table. Zero and an empty field are different: use zero only if it is allowed and represents your data.
If your answer differs from the example, choose Reset and compare every field, including selected units and options. Check percentage versus decimal entry and whether values describe the same period. Round only the final displayed answer when reproducing the formula.
If a discrepancy remains, report the calculator issue with the page address, non-sensitive example inputs, actual result, expected result and a reference for your calculation.