Metric measuring with dual unit tapes

In this country building regulations have been metric since 1972, building plans are metric and most materials are sold in metric quantities. It therefore makes sense to make metric measurements when undertaking a DIY project.

Unfortunately making measurements in metric is hampered by the fact that most British tapes are sold with dual measures.

Most measuring tapes and rulers sold for carpentry, plumbing and other building tasks in Britain are dual unit tapes with both imperial and metric scales. In the case of rulers a user can simply turn the ruler upside down in order to use the other unit as the two scales are printed facing opposite directions. Retractable steel measuring tapes are different. The scales for both upper and lower edges are printed the same way up.

Dual tape in DIY store

Take a simple example like measuring a piece of wood for a cut. The natural way of using the measuring tape is to align the upper side of the tape with the upper edge of the wood and marking the desired cutting position by measuring from the left. The required cutline will then be usually be marked using a set square.

Unfortunately with most dual measure tapes this is only possible using the inch side of the tape. For example if one wants to mark a 40 cm line the inch scale is on the upper part of the tape and the (lower) metric scale is awkward to use.

using dual tape above imperial

The only way to measure the 40 cm cutline in the normal way is to precariously position the lower edge of the tape close to the upper edge of the wood.

Marking below metric edge

This is totally unsatisfactory as measurement accuracy is compromised.

If, as one would do with a ruler, the tape is turned upside down so that the metric side is uppermost the metric scale then appears upside down. The measurement is also made from right to left rather than the usual left to right.

using dual tape upside down

This too is an unacceptable way of working.

The only way to use the tape to measure in metric is to align the lower edge of the tape with the lower edge of the wood. This is counter-intuitive and seems very awkward.

Given that British plumbing fittings went metric in the early 1970s and that all building plans have been in metric since 1972 and since almost all building materials are sold in metric, it is very surprising that dual tape measures are not designed to have metric on the upper edge of the tape. If that were the case they would be usable for metric DIY and home use.

Information on metric only tapes is provided on this website.

The only way to measure the 40 cm cutline in the normal way is to precariously position the lower edge of the tape close to the upper edge of the wood.