Calculate blast yield, energy released, or TNT energy per ton from the other two values in joules, kilojoules, megatons, or kilotons.

Convert a stated energy to TNT-equivalent units.

Energy reference

Blank uses the conventional 4.184 GJ per ton. A custom value defines a different energy reference.

Blast Yield Formula

The blast yield calculation compares total energy released to the energy released by one ton of TNT. The calculator uses tons of TNT equivalent as the base yield unit, then converts the result to kilotons or megatons.

Y = E / ET
  • Y = blast yield in tons of TNT equivalent
  • E = total energy released, in joules
  • E_T = energy released by one ton of TNT, in joules per ton

To calculate total energy released when you know the blast yield:

E = Y × ET

To calculate the energy value being used for one ton of TNT:

ET = E / Y

Select the value to solve for and enter the displayed inputs. The optional energy reference defaults to the conventional 4.184 GJ per ton when blank:

  • Energy Released: calculated from blast yield multiplied by energy per ton of TNT.
  • Energy Released by One Ton of TNT: calculated by dividing total energy by TNT-equivalent tons.
  • Blast Yield: calculated by dividing total energy by energy per ton of TNT, then converting tons to kilotons or megatons.

Common TNT Energy and Yield Conversions

The conventional energy equivalent is exactly 4.184 gigajoules per ton of TNT. This is an energy conversion; equal energy does not imply equal blast effects or safety distances.

TNT equivalent unit Tons of TNT Energy using 4.184 GJ/ton
1 ton 1 ton 4.184 GJ
1 kiloton 1,000 tons 4.184 TJ
1 megaton 1,000,000 tons 4.184 PJ

Unit Equivalent Used for
1 kJ 1,000 J Small energy inputs
1 MJ 1,000,000 J Medium energy inputs
1 GJ 1,000,000,000 J TNT energy per ton and large releases
1 kt 1,000 tons of TNT Blast yield output
1 Mt 1,000,000 tons of TNT Large blast yield output

Example Calculations

Example 1: Calculate blast yield from energy released

You have an energy release of 8,368 GJ and use 4.184 GJ as the energy released by one ton of TNT.

Y = E / ET
Y = 8368 / 4.184 = 2000 tons

Convert tons to kilotons:

2000 / 1000 = 2 kt

The blast yield is 2 kt.

Example 2: Calculate energy released from blast yield

You have a blast yield of 0.5 kt and use 4.184 GJ per ton of TNT.

First convert kilotons to tons:

0.5 kt × 1000 = 500 tons

Then calculate total energy:

E = 500 × 4.184 = 2092 GJ

The energy released is 2,092 GJ.

FAQ

What value should I use for energy released by one ton of TNT?

The conventional TNT equivalent is 4.184 GJ per ton of TNT, or 4,184,000,000 J per ton. Blank in the optional reference field uses this value. A custom value represents a different reference, not a change to the conventional unit definition.

What is the difference between kilotons and megatons?

A kiloton is 1,000 tons of TNT equivalent. A megaton is 1,000,000 tons of TNT equivalent. That means 1 megaton equals 1,000 kilotons.

How do I choose the calculation?

Choose TNT-equivalent yield or energy, then enter the known quantity. Leave the optional energy reference blank to use 4.184 GJ per ton, or enter a custom reference in GJ per ton. To infer a reference, choose Implied energy reference and enter both energy and a positive yield. Zero energy and zero yield do not define a unique reference.