Kilograms of TNT to Calorie (nutritional)

One kilogram of TNT releases 4.184 MJ — enough to shatter windows within several meters and cause serious injury at close range. In open air, 1 kg of TNT produces a blast overpressure lethal to humans within about 2–3 meters. The effect depends heavily on confinement: the same charge inside a vehicle or building is far more destructive than in open ground.

One kilogram of TNT (4.184 MJ) is roughly the kinetic energy of a 1,500 kg car traveling at 75 km/h, or the energy stored in about 120 mL (half a cup) of petrol. It is also the chemical energy in roughly one large meal (1,000 kcal). The difference is that TNT releases its energy in microseconds rather than hours.

Mining engineers express blast charge sizes in kg of TNT equivalent to standardize across different commercial explosives. A typical quarry blast hole uses 5–50 kg of ANFO (ammonium nitrate/fuel oil), equivalent to roughly 4–37 kg TNT. Building demolition charges range from 10 to several hundred kg TNT equivalent, carefully placed at structural weak points.

A standard 155 mm artillery shell contains about 7–11 kg of TNT equivalent. A 500 lb (Mk 82) air-dropped bomb holds roughly 87 kg of TNT equivalent. An RPG-7 warhead is about 1–2 kg TNT equivalent. Anti-tank mines range from 5–10 kg TNT equivalent. These figures represent explosive fill, not total weapon weight.

A standard stick of commercial dynamite (about 200 g, 20 cm long) has a TNT equivalence of roughly 0.25–0.30 kg, since dynamite is about 1.25–1.5× as powerful as TNT by weight. Eight sticks of dynamite are roughly equivalent to one kilogram of TNT. Modern mining rarely uses traditional dynamite, preferring cheaper ANFO or emulsion explosives.

In the late 19th century, nutritionists adopted the kilocalorie as the practical unit for food energy but dropped the "kilo" prefix in everyday speech. A banana labelled "90 calories" actually contains 90 kilocalories (90,000 small calories). Some labels use a capital "C" (Calorie) to distinguish it from the small calorie, but this convention is inconsistently applied and remains a source of confusion worldwide.

Lowercase cal denotes a small calorie; a kilocalorie is 1,000 small calories of the same variant. A food Calorie (Cal), however, already means one kilocalorie. In this converter, 200 food Calories = 200 nutritional kcal = 836.8 kJ. The separate small thermochemical calorie selection uses 4.184 J per cal th, while each nutritional selection uses 4,184 J per Cal or kcal.

This converter does not determine a daily energy requirement; it only converts a supplied energy quantity. For example, 2,000 food Calories means 2,000 nutritional kcal, or 8,368 kJ, using the selected convention. That conversion example is not a personal intake recommendation.

Kilojoules are an SI energy unit, while kilocalories remain common for food-energy quantities. For the food-energy convention used here, multiply kcal by 4.184 to get kJ, or divide kJ by 4.184 to get kcal. For example, 2,000 kcal = 8,368 kJ. The food Calorie (Cal) and nutritional kcal selections use the same conversion factor.

Wilbur Atwater and colleagues in the 1890s used bomb calorimeters to burn food samples and measure heat released. They established that carbohydrates yield ~4 kcal/g, protein ~4 kcal/g, and fat ~9 kcal/g — the Atwater factors still printed on food labels today. Modern methods use chemical analysis and Atwater factors rather than direct calorimetry for every product.