Which ton is referred to in 'a ton of TNT'?

The energy equivalent of 1 ton of TNT is defined to be 4.184 GJ, which is 4.184 × 10⁹ J (not 1 GJ as stated in the posted question). Since this is a defined value, it is considered exact. Reference http://ws680.nist.gov/publication/get_pdf.cfm? read more

It actually does not really refer to any specific ton — though initially the tonne (metric ton) was intended, rounding the energy release of one gram of detonating TNT to 1000 calories/gram. It really means one gigacalorie, the “ton” designation is an illustrative comparison. read more

A ton of TNT or tonne of TNT is a unit of energy equal to 10 9 (thermochemical) calories, also known as a gigacalorie (Gcal), equal to 4.184 gigajoules (GJ). A kiloton of TNT or kilotonne of TNT is a unit of energy equal to 10 12 calories, also known as a teracalorie (Tcal), equal to 4.184 terajoules (TJ). read more

1 short ton (ton in North America) = 907.18474 kg = 2000 lb 1 metric ton (tonne) = 1000.0 kg A ton of TNT or tonne of TNT is a unit of energy equal to 109 (thermochemical) calories, also known as a gigacalorie (Gcal), equal to 4.184 gigajoules (GJ). read more