Measuring tools. View of measuring tools of varying precision. These tools are all used in different circumstances, depending on the accuracy required. The least accurate is the tape measure (lower right), which measures distance of up to 10 metres. They are commonly used to find the dimensions of a room, and distances of a similar scale. The vernier calipers (top) are used to measure smaller distances; between one and 20 centimetres. The micrometer screw gauge (lower left) is the most precise. It is used to measure distances of up to two and a half centimetres, and it is accurate to within one hundredth of a millimetre.