The scalemeter (sometimes called architect scale) is a special ruler "Ruler (instrument)") whose cross section has a triangular shape (Geometry) with the aim of containing different scales in the same ruler. It is frequently used to measure in drawings containing various scales "Scale (cartography)"). On its edge it contains a range with calibrated scales and simply rotate it on its longitudinal axis to see the appropriate scale. It can be used to measure undefined scales on your body (doing the calculations mentally).[1]​.

Rulers and scales have traditionally been made of wood (generally beech wood) and in order to maintain precision and longevity, materials have been used that offer durability and stability at the same time. Nowadays, the most common thing is to find scalemeters made of plastic or aluminum. Depending on the number of scales included in the rule, the cross section can be flattened (two or four scales), triangular (six scales, which is usually the most common) or square (eight scales).

Metric units

The scales used in Latin America use measurements in millimeters and centimeters, while in Europe and other areas that adopt the metric system they are designed with scales of said system. In this way, the drawings contain the usual scales and units. Standardized length units in the SI system may differ in different countries; Generally, millimeters (mm) are used in England and meters (m), while in France we generally work in centimeters (cm) and meters.

Flat scalemeters contain two scales that are usually:.

In triangular scales, the usual values ​​are:.

In general, it is recommended to avoid scales that are multiples of 3 such as 1:75, 1:300, 1:600, 1:900...