TNT Equivalent Calculator

Created by Rahul Dhari
Reviewed by Steven Wooding
Based on research by
United Nations IATG 01.80 - Formulae for Ammunition Management - Clause 9.1 (March 2021)
Last updated: Jan 12, 2023

This TNT equivalent calculator will help you find the TNT equivalent weight for different explosives. Using this calculator, you can find answers to questions like how many kilograms of C4 produces energy equivalent to 1 kg of TNT.

There was a need to adopt a universal quantity to compare the energy output of various explosives. TNT (trinitrotoluene) equivalent weight was chosen because its blast characteristics resemble most solid-type explosives. Blast characteristics data is crucial to design protective structures, and the number of explosives help determine the pressure loads (see blast radius calculator) acting on the structures during an explosion event. In addition to this, it is also used as a unit of energy conversion (see energy conversion calculator).

Read on to understand how to calculate TNT equivalence using our tool.

TNT Equivalence

TNT equivalence is a function of the ratio of heat produced during detonation. A kilogram of TNT produces 4.1844.184 MJ of energy. For an explosive having a heat of detonation HexpH_\mathrm{exp}, the TNT equivalent weight WeqW_\mathrm{eq} is:

Weq=WexpHexpHTNT,W_\mathrm{eq} = W_\mathrm{exp} \frac{H_\mathrm{exp}}{H_\mathrm{TNT}},

where the heat of detonation is expressed in MJ/kg\mathrm{MJ/kg} and weight is in kg\mathrm{kg}. The ratio of heat of detonation is called the TNT factor. The table below contains some of the common explosives and their heat of detonation:

Explosive

Heat of detonation (MJ/kg)

Factor

TNT

4.184

1.000

Baratole

2.209

0.528

Comp B

4.566

1.091

C4

4.715

1.127

HMX

4.821

1.152

Pentolit 50/50

4.545

1.086

PBX 9407

4.757

1.137

PETN

4.906

1.173

RDX

4.821

1.152

Tetryl

4.481

1.071

NQ

3.165

0.756

NG

4.715

1.127

Ammounium nitrate

1.757

0.420

ANFO

3.682

0.880

Natural gas

0.669

0.160

Ammonium picrate

4.058

0.970

HBX-3

4.268

1.020

Torpex

5.021

1.200

Tritonal

3.891

0.930

Amatol 80/20

4.895

1.170

Tetrytol 75/25

5.021

1.200

Torpex

5.021

1.200

Did you know?
Only one-third of the chemical energy is released upon detonation; the rest is released at a slower rate as the explosive burns through, which is a function of heat of combustion.

How to calculate TNT equivalent

Now that you know what is TNT factor is, we will use it to calculate TNT equivalences. You can do that using the accompanying tool.

  1. Enter the heat of detonation of the explosive.
  2. Insert the heat of detonation for 1 kg of TNT (4.184 MJ/kg4.184~\mathrm{MJ/kg}).
  3. Fill in the weight of the explosive.
  4. The calculator will return the TNT factor and TNT equivalent weight.

We have already input data for some common explosives. Click on the drop-down list to pick one.

Using the TNT equivalent calculator

Using our calculator, let's calculate the TNT equivalent weight of 6.5 kg of C4.

To calculate the TNT equivalent weight:

  1. Select "C4" from the list of explosives.

  2. The calculator sets the heat of detonation as 4.71 MJ/kg and 4.184 MJ/kg for C4 and TNT, respectively.

  3. The TNT factor is:

TNT factor=HexpHTNT=4.714.184=1.127\qquad \footnotesize \begin{split} \mathrm{TNT \ factor} &= \frac{H_\mathrm{exp}}{H_\mathrm{TNT}}\\[1.5em] &= \frac{4.71}{4.184} = 1.127 \end{split}
  1. Enter the weight of C4 as 6.5 kg.

  2. You can obtain the TNT equivalent weight by multiplying the factor with the weight of C4:

Weq=6.5×1.127=7.325 kg of TNT\qquad \footnotesize \begin{split} W_\mathrm{eq} &= 6.5 \times 1.127\\ &= 7.325~\mathrm{kg\ of\ TNT} \end{split}

FAQ

What is TNT?

TNT is one of the most commonly used explosives for military and mining operations. It stands for "2,4,6-trinitrotoluene". One kg of TNT releases 4.184 MJ of energy upon detonation. This value helps compare various high-energy events.

What is TNT equivalent factor?

TNT equivalent factor is a physical quantity used to compare explosives based on their heat of detonation. It was adopted as a benchmark because blast characteristics resemble most solid-type explosives. Mathematically, it is the ratio of heat of detonation of explosive and TNT.

How do I calculate TNT equivalent factor?

To calculate TNT equivalent factor:

  1. Find the heat of detonation of the explosive in kJ/kg.

  2. Divide the heat of the detonation of the explosive by the heat of the detonation of TNT (4,184 kJ/kg) to obtain the TNT equivalent factor.

How much TNT is equivalent to 3 kg of C4?

3 kg of C4 has the TNT equivalent weight of 3.381 kg of TNT. Using the heat of detonation of C4 and TNT as 4.71 MJ/kg and 4.184 MJ/kg, respectively:

Wexp = 3 × 4.71/4.184 = 3.381 kg of TNT.

Rahul Dhari
Select an explosive 💣 to begin.
Explosive
TNT
Heat of detonation
Heat of detonation of explosive (Hexp)
J/kg
Heat of detonation of TNT (Htnt)
J/kg
TNT factor
Weight
Weight of explosive (Wexp)
lb
TNT equivalent weight (Weq)
lb
of TNT
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