Inch-Pound to Kilograms of TNT

Inch-pounds provide finer resolution for small fasteners where foot-pound values would be fractions (e.g., 3 in·lb vs 0.25 ft·lb). Electronics assembly, firearms scope mounting, and bicycle component installation all specify inch-pounds because over-torquing a small screw by even one foot-pound can strip threads or crack housings.

On an M3 screw into aluminum (spec: 5 in·lb), exceeding by 2 in·lb — a 40% overload — can strip the threads or crack a thin boss. Small fasteners have almost no safety margin because the thread engagement area is tiny and the materials (plastic, aluminum, brass) are soft. This is why electronics repair shops use beam-type or preset click torque drivers accurate to ±0.5 in·lb, and why aerospace assembly procedures treat inch-pound specs as hard limits, not suggestions.

Laptop hinge screws typically require 2–5 in·lb, hard drive mounting screws 2–4 in·lb, and motherboard standoff screws 5–8 in·lb. Going beyond the spec risks cracking plastic bosses or stripping soft aluminum threads. A precision bit driver with a torque limiter is essential for electronics repair work.

Dimensionally they are identical — force times distance — but context differs. As torque, 1 in·lb means one pound-force applied at one inch from a pivot. As energy, it means one pound-force pushing through one inch of linear displacement (0.11299 J). In practice, inch-pounds almost always refer to torque in mechanical specifications.

Scope rings and bases use small screws that are easily damaged, and consistent clamping force is critical for zero retention under recoil. Typical specs are 15–25 in·lb for ring screws and 30–65 in·lb for base screws. Under-torquing lets the scope shift; over-torquing cracks the scope tube or strips the screw. A dedicated inch-pound torque wrench is considered essential kit for precision rifle setup.

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.