There is as such no percentage required to be eligible for SBI PO exam.

You have to complete below eligibility criteria

1- You must be graduated in any discipline from a recognised University or any equivalent qualification recognised by the Central Government.

2- You must not be below 21 years or above 30 years as on April 01, 2017 i.e. they must have been born not earlier than April 02, 1987 and later than April 01, 1996 (both days inclusive).

There is relaxation of age for reserved category.

Good Luck!!