The modulor is a measurement system detailed by the Swiss architect Le Corbusier (in collaboration with André Wogenscky) in 1948 and published in the book Le Modulor followed by Le Modulor 2.[1]​.

This system seeks to establish a harmonious scale for architectural and urban design, using the proportions of the human body as a base.[2] Inspired by Leonardo da Vinci's Vitruvian Man and the golden section, Modulor combines mathematics and biology to propose a guide of measurements that are comfortable, functional and aesthetically pleasing for human beings.[3]​.

Le Corbusier started from a standard height of 1.83 meters (6 feet) and divided the body into segments, considering everyday postures and movements. In this way, the dimensions of the Modulor range from 1.13 meters (which corresponds to the height of the navel of a 1.83 meter person) to other measurements that are multiplied and divided following the golden ratio (1.618), generating a series of numbers that, according to Le Corbusier, help design spaces and objects on a human scale.

The measurements start from the measurement of the man with his hand raised (226 cm) and from its half, the height of the navel (113 cm).[4] From the first measurement, successively multiplying and dividing in the same way by the golden number, the so-called blue series is obtained, and from the second, the red series is obtained in the same way. Each being a Fibonacci sequence and allowing thousands of harmonic combinations.

Modulor was used in many of Le Corbusier's projects, such as in the Unité d'Habitation of Marseille, where these proportions were applied in the apartments and common spaces, with the aim of optimizing the comfort and harmony of the space.

An image of the Modulor appears on the Swiss 10 CHF banknote.