Map area calculator and price calculator google api question

Question

I need some help. Here is what I am trying to do. This is for a service business, mowing yards.

I am wanting to use google maps or something similar where customers can outline the property lines on the map so we know where the scope of work is to take place.

I would also like for this to measure the square footage so the customer can input this into a calculator along with other variables so they can receive a price estimate for the job. Example:

Price Calculator Sq footagre: 1200 Service A: Yes Service B: Yes Times for service C: 3

So I am trying to create something where the customer can outline on a map, it measures the sq footage and the customer is able to receive a price estimate.

Thank you for all of your help!