How to calculate CPI rental increase California

[Kenneth Woodall]

California's AB 1482 law states that rents can only increase 5% + CPI (up to 10%) per year. 

The CPI must be calculated from April-April of the previous year.

1.) I have a tenant renewing their lease in 2 months, but the April CPI isn't out yet -- what's the best way to calculate the rental increase?

2.) If I'm using previous year's numbers, CPI looks to be 4.1%, so adding 5%, that would be 9.1%, correct?

3.) Does anyone have a simple way to find this info, or a free calculator online?

This is for units in San Bernardino County.