Nuclear Fusion Energy Calculator

Work out nuclear fusion energy instantly with clear inputs, formula shown and shareable results.

About Nuclear Fusion Energy Calculator

The deuterium-tritium reaction releases 17.6 MeV, most of it carried by the 14.1 MeV neutron. Because the fuel nuclei are so light, the energy per kilogram beats uranium fission by roughly a factor of four - about 3.4e14 J/kg for D-T against 8.2e13 J/kg for U-235.

Formulas

Reaction count

N = (mass / (2 x average molar mass)) x NA

Energy released

E = N x energy per reaction

Worked example

With the default values below, Nuclear Fusion Energy Calculator returns Total Energy Released of 3.39628 × 10¹¹. Change any input above and every figure here is recalculated in your browser.

Inputs used

Mass of fuel fusedminimum 0 g: 1 g
Energy per fusion reactionminimum 0 MeV: 17.6 MeV
Average molar mass of the fuel pairminimum 0 g/mol: 2.5 g/mol

Results

Total Energy Released: 3.39628 × 10¹¹ J
Number Of Fusion Reactions: 1.2044 × 10²³
Energy Per Kilogram Of Fuel: 3.3963 × 10¹⁴ J/kg
Energy Density Relative To U-235 Fission: 4.142

Step by step

1Values used
2Reaction count
3Energy released
4Total Energy Released= 339,628,000,000.00000 J
5Number Of Fusion Reactions= 120,443,000,000,000,000,000,000.0000
6Energy Per Kilogram Of Fuel= 339,628,000,000,000.0000 J/kg
7Energy Density Relative To U-235 Fission= 4.142

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 5 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 is fusion harder than fission?

Because two positively charged nuclei must be forced together against Coulomb repulsion, needing temperatures over 100 million kelvin. Fission only needs a neutron to arrive.

Where does the D-T energy go?

About 3.5 MeV to the helium nucleus, which stays in the plasma and heats it, and 14.1 MeV to the neutron, which escapes and is captured in the blanket.