tolerances

What is the meaning of calculation?

Do you mean specification ?

If so there are several methods are there

You may refer ISO286 or ANSI B4.1 or 4.2(Metric) if you want

But these are basically general purpose guidelines and you have to select them.

The other way is the statistical design of tolerances where you come back from the final requirements and trace back to root. Here you can go for equal spreads, un-equal standard spreads (eg IT7/it6), or tolerancing based on manufacturability.

The total design of tolerances is a vast subject and difficult to cover here. We had a total subhect on the statistical design of tolerances in the SQC.

If you require the specifics, may be we can help you.

You can't.

A. Optimally, this requires a lot of insight into (always with regard to what is achievable & desirable tolearance-wise, incl. best practices) 1) the actual functionality of the machine you are designing, 2) how parts are located when assembled, 3) how parts are manufactured, etc This would be the equivalent of a full university course, several books and at least a few years of hands-on experience.

B. Sub-optimally, you need to be aware at least of the functionality requirements of your machine:

I.e. you are designing a truck that needs to fit under bridges of, say, 6.5m height. Well, you can go to your assembly and call out a height tolerance "max 6500mm". In this bare context, you'd be more correct than someone arbitrarily (and stupidly) specifying 6500+0/-1mm!!! How to translate your functional tolerances to part and manufacturing/ assy/ material prop. tolerances is where the deep insights are needed (point A), which you don't seem to have.

So you can't.

And no, browsing the net for free GD&T material (while not a bad idea) will not even begin to enlighten you, perhaps will even confuse you more...

And yes, the calculus of tolerancing goes way beyond 'stacking' (tip: ...which should not much happen anyway if you want to build things with reasonably economical/ feasible tolerances)

Don't worry, many people who claim to know how to tolerance things are basically ignorant. Even 'reading' tolerances correctly is elusive to some. Proper torerancing is one of the most difficult things in engineering.

I hope my reply doesn't discourage you, but instead prompts you to seek proper education on the subject. Other members may be able to provide refs to good books and courses, depending on your location.