Watt-hours to Tons Of TNT (Wh to tTNT)

1 watt-hour equals 8.604206501×10⁻⁷ tons of TNT (rounded).

1 watt-hour = 8.604206501×10⁻⁷ tons of TNT

How to convert watt-hours to tons of TNT

To convert watt-hours to tons of TNT, multiply the number of watt-hours by 8.604206501×10⁻⁷. The factor is rounded to 10 significant digits. To go the other way, multiply tons of TNT by 1,162,222.222 (rounded).

tons of TNT = watt-hours × 8.604206501×10⁻⁷

Example: 10 watt-hours = 0.000008604206501 tons of TNT.

The 'calorie' on food labels is really a kilocalorie. The thermochemical calorie (4.184 J) is used here unless marked IT.

About these units

Watt-hour (Wh)

Metric (SI)Current unit

Exactly 3,600 joules, the energy used by a one-watt device in an hour. Battery capacities are quoted in watt-hours.

Pair a power unit with a unit of time and you get the watt-hour: one watt sustained for one hour, which works out to 3,600 joules. The watt itself was adopted at the second International Electrical Congress in 1889, in the same session that adopted the joule, so the two units share a birthday even though the watt-hour is the one people read off batteries.

Battery capacity is where it earns its keep. Multiplying amp-hours by the battery voltage gives an estimate of watt-hours, so a 2,500 mAh lithium-ion cell at 3.7 V holds roughly 9.25 Wh. That is why a 500 mA USB device runs about 3.7 hours on it rather than five: the cell voltage, not the 5 V from the port, sets the energy.

For scale, an alkaline AA battery holds about 9 kJ, which is 2.5 Wh. A 12 W LED lamp left on for an hour uses 12 Wh, and a 40 W appliance running for 25 hours uses 1,000 Wh.

1 watt-hour = 3,600 joules (exactly).

Sources: Wikipedia: Watt-hour; Wikipedia: Joule; Wikipedia: Orders of magnitude (energy)

Ton Of TNT (tTNT)

ScientificCurrent unit

Exactly 4.184 gigajoules by convention (one tonne of TNT). The unit for explosions; a megaton is a million of them.

Explosive yields are quoted against a reference charge, and the ton of TNT is the one that stuck. Real TNT does not release a single fixed amount of energy: measured values run near 4,686 joules per gram, calculations give about 4,853, and a large open blast can burn more of its products in air than a small one. To sidestep the argument, the energy of a gram of TNT was set by convention at 4,184 joules, one kilocalorie, so a ton is exactly 4.184 gigajoules.

That makes a kiloton 4.184 terajoules and a megaton 4.184 petajoules. The scale is mostly used for nuclear weapons and asteroid impacts. The Hiroshima bomb is usually put at about 15 kilotons (63 terajoules) and the Nagasaki bomb at about 20 kilotons (84 terajoules). NIST lists the ton of TNT at 4.184 x 10^9 joules as an exact factor, matching the convention used here.

1 ton of TNT = 4,184,000,000 joules (exactly).

Sources: Wikipedia: TNT equivalent; NIST SP 811, Appendix B.8

Related conversions

See all energy units.