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Nuclear Fission Energy Calculator

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

About Nuclear Fission Energy Calculator

Each uranium-235 fission releases about 200 MeV, and a gram contains 2.56e21 atoms, so fissioning one gram liberates 8.2e10 J - roughly a megawatt-day, or the energy of 3.4 tonnes of coal. That million-fold energy density over chemical fuels is the entire case for nuclear power.

Formulas

Atoms in the sample

N = (mass / molar mass) x NA

Energy released

E = N x energy per fission

Worked example

With the default values below, Nuclear Fission Energy Calculator returns Total Energy Released of 8.20998 × 10¹⁰. Change any input above and every figure here is recalculated in your browser.

Inputs used

Mass of fissile material consumedminimum 0 g
1 g
Energy released per fissionminimum 0 MeV
200 MeV
Molar mass of the nuclideminimum 0 g/mol
235.044 g/mol

Results

Total Energy Released
8.20998 × 10¹⁰ J
Number Of Fissions
2.5621 × 10²¹
Same Energy In Megawatt-Days
0.9502
Equivalent Mass Of Coal
3,420.825 kg

Step by step

  1. 1Values used
  2. 2Atoms in the sample
  3. 3Energy released
  4. 4Total Energy Released= 82,099,800,000.00000 J
  5. 5Number Of Fissions= 2,562,130,000,000,000,000,000.0000
  6. 6Same Energy In Megawatt-Days= 0.9502
  7. 7Equivalent Mass Of Coal= 3,420.825 kg

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 200 MeV per fission?

It is the average for uranium-235, split mostly between the kinetic energy of the fragments, with about 5% carried away by neutrinos and unavailable.

How much uranium does a reactor use?

A 1 GW electrical plant at 33% efficiency fissions roughly 3 kg of uranium-235 a day, though the fuel loaded is far heavier because of enrichment levels.

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