Perusmitat

Perusmitat is a Finnish term meaning basic or standard dimensions. In engineering, construction, and product design, perusmitat refers to a set of fundamental measurements that define a category of parts or products. They act as reference sizes from which other dimensions, tolerances, and fit are derived. The concept helps ensure interoperability and interchangeability among components and suppliers, and it supports consistent design, procurement, and manufacturing processes.

Perusmitat are not universal constants; they are defined in standards and normative documents at national and international levels. In Finland they are often described in materials and standards published by the Finnish Standards Association (SFS) or other standardization bodies, and they may align with ISO, EN, or EN-NORM families used across Europe. Care is taken to specify the domain, such as mechanical components, architectural elements, or furniture, because perusmitat differ between industries and even between product families.

Examples vary by field. In mechanical engineering, a perusmitat might designate a base size for a bolt or shaft family; in construction, standard door or window heights; in modular furniture, common unit or module sizes. The perusmitat concept is used to derive tolerances, production plans, and procurement catalogs, enabling parts from different manufacturers to fit a common system.

In practice, designers reference perusmitat when developing new products and updating catalogs. Standards may evolve, so projects often specify the applicable perusmitat standard version to ensure alignment with current practices.