The work defines the concept of linguistic complexity of a text, which affects the difficulty of its translation. Absolute unconditional and relative conditional factors of difficulty are distinguished, the consideration of which makes it possible to rationalize translation activities. The concept of laboriousness is introduced in relation to the translation of the text. Describes methods for quantifying the complexity of a text and the complexity of its translation. The manual is intended for translators of scientific and technical literature, as well as for those who are engaged in the organization, planning and scientific research of translation activities.