Relative effectiveness factor or R.E. factor is a measurement of an explosive's power for military demolitions purposes. It is used to compare an explosive's effectiveness relative to TNT by weight only, TNT equivalent/kg (TNTe/kg). This enables engineers to substitute one explosive for another when they are calculating blasting equations that are designed for TNT. For example, if a timber cutting charge requires 1 kg of TNT to work, it would take 0.42 kg of ONC, 0.6 kg of PETN, 1.25 kg of ANFO, or 2.22 kg of AN to have the same effect.