I want to convert a string to hash and divid into n bucket

Question

Problem: I want to divide the M strings into N bucket as uniformly as possible.

One solution I was thinking is,

1. Create a hash of string
2. Convert the hash to integer by mapping ascii value of each character in hash
3. Sum up those ascii values
4. Divide the sum by N

Uniform distribution I believe will be solved by hashing but not sure converting to ascii will change anything.

Please suggest better solution if you have one.

Thank you in advance