As woodworkers based in the UK, we have the unenviable task of having to work in both Metric (mm) and Imperial (inches) units at the same time. Saw mills and woodworking tool manufacturers don’t seem to have found any consensus on a default unit of measurement. This often leads to confusion when trying to establish what we are actually purchasing. For instance, is 18mm plywood is actually 18mm or is it ¾ inch which is actually 19.05mm. The answer varies from store to store.
I believe the whole world has this problem, but maybe not quite as pronounced as it is here in the UK where we have officially converted to metric, but still use MPH on the roads and weigh babies in Pounds (lbs). Personally, I cannot wait for the day that we finally ditch the archaic imperial units and finally embrace the simplicity of a fully metric world. Though I don’t see that happening any time soon.
Instead, we must be bi-lingual with our measurements. So with that in mind, here are some helpful conversions.
Common Conversions
| FRACTION | DECIMAL | MILLIMETER |
|---|---|---|
| 1/32 | 0.03125 | 0.79375 |
| 1/16 | 0.0625 | 1.5875 |
| 1/8 | 0.125 | 3.175 |
| 3/16 | 0.1875 | 4.7625 |
| 1/4 | 0.25 | 6.35 |
| 5/16 | 0.3125 | 7.9375 |
| 3/8 | 0.375 | 9.525 |
| 7/16 | 0.4375 | 11.1125 |
| 1/2 | 0.5 | 12.7 |
1 foot = 12 inches
| FRACTION | DECIMAL | MILLIMETER |
|---|---|---|
| 5/8 | 0.625 | 15.875 |
| 11/16 | 0.6875 | 17.4625 |
| 3/4 | 0.75 | 19.05 |
| 13/16 | 0.8125 | 20.6375 |
| 7/8 | 0.875 | 22.225 |
| 15/16 | 0.9375 | 23.8125 |
| 1 | 1 | 25.4 |
| 1 1/2 | 1.5 | 38.1 |
| 2 | 2 | 50.8 |
1 metre = 100 centimetres = 1000 millimetres
Are our project plans Imperial or METRIC?
We do our very best to keep things simple. That said, it isn’t always easy in the wacky world of lumber dimensions.
With each project, we try to find the best solution. Sometimes that is working in imperial, other times metric, but most of the time we provide both. The only thing we ask, is that you don’t use both. Pick a unit at the start of the project and stick with it.
Each project will clearly state what units the plans are written in, and if you still have questions send us a message before purchase.
