Megatons of TNT to Kilojoule
MtTNT
kJ
Conversion History
| Conversion | Reuse | Delete |
|---|---|---|
1 MtTNT (Megatons of TNT) → 4184000000000 kJ (Kilojoule) Just now |
Quick Reference Table (Megatons of TNT to Kilojoule)
| Megatons of TNT (MtTNT) | Kilojoule (kJ) |
|---|---|
| 0.001 | 4,184,000,000 |
| 0.01 | 41,840,000,000 |
| 0.1 | 418,400,000,000 |
| 0.475 | 1,987,400,000,000 |
| 1 | 4,184,000,000,000 |
| 10 | 41,840,000,000,000 |
| 50 | 209,200,000,000,000 |
About Megatons of TNT (MtTNT)
A megaton of TNT equals 4.184 × 10¹⁵ joules — one million metric tons of TNT — and is the unit used to quantify thermonuclear weapon yields and very large natural catastrophic events. Modern strategic nuclear warheads typically yield 0.1–1 megaton; the largest ever detonated, the Soviet Tsar Bomba (1961), yielded approximately 50 megatons. The energy of the asteroid impact that caused the Cretaceous–Paleogene extinction is estimated at around 100 million megatons.
The US W88 thermonuclear warhead yields approximately 0.475 megatons. The Tsar Bomba, the largest nuclear weapon ever tested, yielded about 50 megatons.
About Kilojoule (kJ)
A kilojoule (kJ) equals 1,000 joules and is one of the most practical SI energy units for everyday human-scale work. Food energy is commonly labelled in kilojoules in Australia, the EU, and many other countries — the same information that the US labels in Calories. Physical exercise and metabolic rates are often quoted in kilojoules per hour. One kilojoule is roughly the energy released by a small firecracker, or the kinetic energy of a tennis ball traveling at 160 km/h.
A 100 mL glass of orange juice contains about 180 kJ of food energy. Running 1 km burns approximately 200–300 kJ depending on body weight.
Megatons of TNT – Frequently Asked Questions
How powerful is one megaton of TNT?
One megaton equals 4.184 × 10¹⁵ joules — the energy of burning about 120 million liters of petrol or the total electricity output of a large power plant running for 50 days. A 1-megaton airburst would flatten reinforced concrete buildings within 2 km, cause third-degree burns at 10 km, and break windows at 40+ km. It is roughly 67 times the Hiroshima bomb.
What was the yield of the Tsar Bomba and why was it so large?
The Soviet AN602 "Tsar Bomba," detonated on 30 October 1961, yielded approximately 50 megatons — the largest human-made explosion in history. It was a three-stage thermonuclear device originally designed for 100 Mt but scaled down by replacing the uranium tamper with lead to reduce fallout. The fireball was 8 km wide, and the mushroom cloud rose 67 km. It was a propaganda weapon with no practical military use.
What are the yields of modern nuclear warheads in megatons?
Modern strategic warheads are smaller than Cold War designs because accuracy improved. The US W88 yields about 0.475 Mt; the W76-1 about 0.1 Mt. Russian RS-28 Sarmat MIRVs carry warheads estimated at 0.5–0.8 Mt each. Military planners found that several smaller warheads (MIRVs) destroy more area than one large one due to the cube-root scaling of blast radius with yield.
How does the megaton scale apply to asteroid impacts?
The Chicxulub impact that ended the dinosaurs released roughly 100 million megatons (10²³ J). The Tunguska event (1908) was 3–15 megatons. NASA's planetary defense threshold is objects capable of 1+ megatons of damage. A 50-meter iron asteroid striking Earth at 20 km/s would release about 10 megatons — enough to obliterate a major city.
Why did nuclear weapon yields decrease after the 1960s despite advancing technology?
Accuracy replaced raw yield. A 0.5 Mt warhead landing within 100 meters of a target destroys it just as effectively as a 10 Mt warhead landing 1 km away. MIRVed missiles carrying 6–10 smaller warheads also cover more total area than one massive bomb. The US retired its last megaton-class warhead (the B83) in 2022, relying entirely on sub-megaton weapons.
Kilojoule – Frequently Asked Questions
Why do Australian food labels show kilojoules instead of calories?
Australia, New Zealand, and the EU mandate SI-based labeling, so food packages list energy in kilojoules. The US and Canada stuck with kilocalories (branded as "Calories"). To convert, divide kJ by 4.184 — a 500 kJ snack bar is about 120 kcal. Most Australian shoppers learn the kJ scale by familiarity rather than converting every time.
How many kilojoules does a person burn walking for 30 minutes?
A 70 kg person walking briskly at 5.5 km/h burns roughly 600–700 kJ in 30 minutes (about 150–170 kcal). That is roughly one banana or a small flat white. Running the same distance roughly triples the kilojoule burn because the body must lift itself off the ground with every stride.
What is the difference between kJ and kcal on a food label?
They measure the same thing — food energy — in different units. One kilocalorie (kcal) equals 4.184 kilojoules (kJ). European and Australian labels show both; US labels show only kcal (labelled "Calories"). A 2,000 kcal/day diet is 8,368 kJ/day. Nutritionists consider the two interchangeable for dietary guidance.
How much energy in kilojoules does a smartphone battery hold?
A typical smartphone battery rated at 15 Wh holds about 54 kJ. That is roughly the food energy in a single sugar cube (17 kJ per cube times three). A laptop battery at 60 Wh stores about 216 kJ, and a Tesla Model 3 battery pack at 60 kWh stores 216,000 kJ — enough dietary energy to feed a person for about 25 days.
Is a kilojoule a large or small amount of energy?
It is a middle-ground unit — too large for electronics (which use millijoules) and too small for household energy bills (which use megajoules or kWh). One kilojoule is the kinetic energy of a tennis ball served at about 160 km/h, the energy in a small sip of juice, or the heat generated by a 100 W bulb in ten seconds. It sits at the human snack-and-exercise scale.