It is difficult since there are a lot of variables some of which you can control and others which you cannot.
Factors to consider:
Are you expecting social security benefits?
Will you have a defined benefit pension?
What do you expect your expenses to be in retirement?
What will inflation between now and then be?
What gain can be expected on investments?
What salary growth do you expect?
etc. etc. etc.
The figures I have seen most often are a minimum of 10% with a desired savings/investing rate of 15%. This might include an employer matching amount in a retirement account.

Bob ... who has never heard anyone complain that they saved too much during their wage earning years.