This website has some easy to understand information on sampling tables:
The first table gives us the code for the sample size based on our lot/batch size:
For thie table if we’re dealing with general inspection levels we can choose between:
a. Reduced (General inspection level 1)
b. Normal (General inspection level 2)
c. Tightened (General inspection level 3)
Once we have a code for our choice of inspection level we can then move to the second table to determine our sample size.
If for example our lot size is 1000 and our inspection level has been decided as level 2 (normal) then our code letter is “J”. This indicates a sample size for this lot as 80. If we have decided that our AQL (Acceptance Quality Level) level is 1 then we will accept the lot/batch if we have less then or equal to 2 rejects in the 80 sampled. If we have 3 rejects in the 80 sampled then we reject the lot/batch.