Pick a state (28 states included). Each state has a unit hierarchy (big -> small). You can edit the unit definitions for any state, then enter two areas and Add or Subtract them. Results show in the state's native mixed units and in square meters.
States included: Andhra Pradesh, Arunachal Pradesh, Assam, Bihar, Chhattisgarh, Goa, Gujarat, Haryana, Himachal Pradesh, Jharkhand, Karnataka, Kerala, Madhya Pradesh, Maharashtra, Manipur, Meghalaya, Mizoram, Nagaland, Odisha, Punjab, Rajasthan, Sikkim, Tamil Nadu, Telangana, Tripura, Uttar Pradesh, Uttarakhand, West Bengal.
Presets provide commonly-used hierarchical units, but local usage can vary — edit unit ratios if you need exact local figures.
Values are converted to square meters for exact arithmetic (editable smallest unit).