How to measure nut size. Bolts and nuts measure in different ways, however, they are key to each other. For example, nuts rarely use more than one measurement, while bolts can have up to four.
Nuts are measured by their width and then the thread pitch. Bolts meanwhile are also measured by their length and diameter as well as the thread pitch.
However, both cannot be interchanged if they come from different measurements simply because they will not fit together properly when used.
So it’s best to make sure that all nuts and bolts being used for an application have the right measurements.
How to measure nut size
First, place the end of a measuring tape on one of the flat sides of the nut’s outer perimeter this will be your starting point.
Now stretch the end of the tape measure across the nut’s diameter to the flat-side directly across from it (in this case this would be the opposite edge). If it is a metric nut, count how many lines are on each side.
Measuring for diameter
Lay the nut down on one side of the inner threads. Set the end of the tape measure at one side of the inner threading and stretch it over to the other side.
This will help you count how many times around it goes, as well as any markings that might be in between for instance every ¼ inch or ⅜ inch, etc.
Then take this measurement across the widest opening that your threads make whether you originally measured from inside out or outside in to find what we’re looking for.
Taking measurements between the flats
Lay the nut on a flat surface so that the hole lays flush. Place the straight part of a tape measure against the flat side of the nut to follow its perimeter as you would with any other tool or object.
If measuring flats, you want to make sure one side is clearly in view for accuracy’s sake. Start at point-A and read up until you reach where point B used to be mark this new distance with a permanent marker and then note your result nearby on the hexagonal cross-section itself (as was done in the example).
One relatively easy way to both accurately and easily measure nuts and bolts is by using calipers which employ various types of jaws or movable pieces that grip an object within a specific range.
This method is known as “micrometer” caliper when discussing nuts and bolts which refer to its accuracy rather than size unlike “linear” which tends to more commonly classify its overall measurement range on objects versus their length alone so as to eliminate human error.
Measurement of thread coarseness or fineness
Count how many threads per inch are present along with the inside diameter of a bolt. Grab a magnifying glass and hold a pin parallel to where you will measure the inside diameter so it makes an imprint on your paper that can be traced when measuring.
Add up the thread numbers in order to get the total number of threads per inch, and make note of it on a piece of paper.
Then work out how many threads there are inside of the nut thickness that corresponds to its nominal diameter.
Simply divide the total number of threads by the number corresponding to the thickness (mm), take into account any scale factors present in denominations used (metric or imperial).
How do you determine bolt nut size?
Bolts are commonly measured by the length of their shank, the size of their bolt heads, and the width of their shanks, depending on which type of bolt they are. Bolts use four measurement types to define what each component is.
Nuts are measured by two measurements instead: the width of the hex shape, and then its thread pitch based on a unit that gauges how far its threads protrude from the nut.
How do you measure a spanner nut?
Wrench sizes are based on the span (distance between two endpoints) and not the width of the handle. For example, the American standard size 10 wrench is actually a 9-inch spanner with a 1-inch wide handle. Older British tools and current US tools have odd intermediate sizes given in fractional values.
Bolt and nut measurement