Accurate measurements separate amateur mistakes from professional results. Here is what you need to know to use a tape measure correctly.
Why you should avoid cloth or plastic tape measures
Cloth and plastic tapes are cheap and flexible, but they are unreliable for precise work:
- They stretch and lose their shape over time
- They sag on longer measurements
- They are affected by temperature and humidity
- Their markings are often less precise
Recommendation: use a good steel tape measure for framing, so that your measurements are accurate.
Understanding the markings
Metric scale
Metric tapes are marked in centimetres (cm), each divided into millimetres (mm):
- Every 1mm: the smallest marks
- Every 5mm: slightly longer marks
- Every 10mm (1cm): the longest marks, with numbers
Imperial scale
Imperial tapes usually show marks down to 1/8 inch, or 1/16 inch on better tapes:
- 1/16 inch: the shortest marks (the finest detail)
- 1/8 inch: medium length
- 1/4 inch & 1/2 inch: longer marks
- Full inches: the longest marks, with numbers
Interactive tape measure
Try it yourself. Enter a measurement below to see where it falls on a tape measure:
How to use the metal hook correctly
The small metal hook at the end of a steel tape is made to move slightly.
Outside measurements
Hook the tab over the edge of the material and pull the tape tight. The hook slides outwards to allow for its own thickness.
Inside measurements
Push the hook firmly against one surface and extend the tape to the opposite one. The hook slides inwards, again allowing for its thickness.
Tip: the 10mm method (the most accurate). For the greatest precision, start the tape at the 10mm mark and subtract 10mm from your reading. This takes the movement of the hook out of the measurement altogether.
Good habits for accurate measuring
- Keep the tape straight and taut
- Measure twice, order once
- Use the same tape for the whole project
- Keep your tape clean and dry
Final thoughts
A good steel tape measure is one of the most useful tools you can own. Learn how the hook works and use the 10mm method, and your measurements will be more accurate straight away.
Try the interactive tool above with different values to see how each measurement looks on a tape.