Resistor tolerances

[MattHollands]

Hi! I'm new here!
I was wondering about resistor tolerances. Imagine I were building a high precision one off device, but only had 5% tolerance resistors. Chances are if I measured enough resistors I would find one at exactly the right resistance. Would this be as precise as buying 1% (or better) tolerance resistors, or is there something intrinsically inaccurate about high tolerance resistors e.g. Will they naturally vary over time more than an lower tolerance resistor?

I hope I have been clear in what I am asking!

Thanks 

[cosmicray]

Imagine I were building a high precision one off device

This is like a rabbit's hole, in how precise your device needs to be, etc, etc. There are extreme examples on eevblog of resistor precision, and they usually are needed because the device/project needs that level of precision. Unless you have a calibrated DMM, you may have to question what value your DMM is presenting vs what resistance is actually present. Matched sets of resistors can, to some extent, be determined via a whetstone bridge.

What resistor value are you trying to obtain ?

[MattHollands]

Thanks for the replies! I don't have any particular value in mind right now, I am just thinking about potentially building my own (basic) LCR meter. I haven't decided what values I would put in series with the DUT but I guess the accuracy of this resistor is quite important to the overall accuracy of the LCR reading. However I suppose as it is only a one-off I could just measure the true value of whatever resistor I use and use that for the calculations instead

[wraper]

With higher tolerance, likely you'll get higher temperature coefficient too and increased resistance change with ageing. Should be aware of carbon resistors too which will come with 5%+ tolerance. Of course there are low tempco high initial tolerance resistors in the wild but this is special case.

[MattHollands]

Ok, I have contacted where I bought my resistors from to see if I can get the datasheets for them. I suspect they won't be brilliant and will end up buying some specially for my case.
Looks like I need to buy some more electronics trays so I can keep my high tolerance resistors from my low tolerance ones!