Amorphous metals display an extraordinary mechanical strength and elasticity and can at the same time be formed like thermoplastic polymers. These properties make them the ideal material for industrial applications where complex parts have to withstand high mechanical loads. In this work, the thermoplastic formability of amorphous metals is evaluated and discussed in connection to their thermophysical properties. Formability is experimentally assessed in thermoplastic deformation experiments with a constant heating rate, and in isothermal experiments. The results are compared to the theoretical formability values calculated from the thermophysical material properties and found to perfectly coincide. The formability of amorphous alloys can be reliably calculated based on a viscosity measurement in the supercooled liquid region. In isothermal experiments, the maximum formability is obtained at the highest temperatures where crystallization can still be avoided.