Sum Insured is calculated as per below calculator -
Covered Area (Sq. ft) * Cost of construction (per sq. ft) = SI for your Building

Now calculation for both the above flats assuming Cost of construction (per sq. ft)= 1000/sq ft -
1- (950 sq ft) * (Rs 1000/sq ft) = Rs 950000/-(SI of Building)
2- (1250 sq ft) * (Rs 1000/sq ft) = Rs 1250000/-(SI of Building)

The contents are assessed on the market value of the items.

* Fire and Earth Quack Insurance is now non tariff, so each comapany can give any rate. So take help of online comparing sites.