Interactive length measurement trainer — 0–150 mm — LC = 0.5 mm
A steel ruler (or steel rule) is the most fundamental linear measuring tool in any engineering workshop. This free online simulator covers 0 to 150 mm with a 0.5 mm least count, matching the standard metric steel rules used in technical and vocational workshops worldwide.
Align the zero end of the rule with one edge of the object. Read the value at the other edge — identify the nearest millimetre mark, then check whether the edge falls on a whole millimetre or the 0.5 mm halfway mark. Avoid parallax error by reading straight down from directly above the scale.
A steel rule has the lowest precision (0.5 mm) in the family of linear measuring tools. For higher accuracy use a Vernier caliper (0.02 mm) or a micrometer (0.01 mm). The steel rule is best for layout work, rough cutting, marking-out, and quick reference measurements in metalwork and fabrication.
This simulator also shows readings in cm and m alongside mm, helping students practise metric unit conversion — a key competency in engineering and construction training programmes.
Suitable for introductory metrology courses, foundation engineering students, workshop induction training, and any TVET or apprenticeship programme requiring basic length measurement competency.