How do we measure resistor tolerance?
Tolerance is in the production process, not in the use of resistance. if you want to know the actual resistance, simply use a multimeter.
you can not measure tolerance with a sample of significant size. nowadays, the manufacturing is so good that in any 2% lot, the parts can be sold at 5%, because they all come very close to the specifications.
you first need a large sample of resistors. it’s a lot of them.
Second, you need an automatic measuring system that can process measurements with a precision greater than the expected tolerance of the resistor.
in the end you will get a Gaussian distribution. The current manufacturing technology is quite good and the bell-shaped curve will be very narrow. The best way is to get the manufacturer’s specifications and trust your data and not try to measure tolerance.
you can not measure the tolerance of a single resistor. you can of course measure the error using a suitable device, high resolution and high resolution. but not tolerance. Tolerance is a statistical result of very large quantities of resistors, normally used in manufacturing. the manufacturing process is controlled to obtain a certain dispersion of the yields.
all resistors must be marked or packaged with tolerance, as this is an important specification parameter. but as users, we just believe the manufacturer.
As the end user, there is no practical way to measure resistance tolerance. the value of the tolerance is almost always marked on the part or traceable by marks on a data sheet. in the case of color-coded resistors, if there is no tolerance band, it is assumed that it is 20%.
If you are determined to get a tolerance rating, you can use a lot of similar parts, such as 60 or 150 pieces (the more you will get better results). you would measure and score each measured value, then apply a basic statistical analysis to determine the upper and lower limits and the mean and standard deviation. then you would have finite numbers for your batch of resistors and that would only apply to that lot.