The formula
ADR = room revenue ÷ room nights sold
Use room revenue only — not food, laundry or anything else on the bill — and leave taxes out. Complimentary rooms are usually left out of both the revenue and the nights, so a free room does not drag the average down. Indian hotels often call the same number ARR, the average room rate.
ADR says how well you priced the rooms you sold; it says nothing about the rooms you did not sell. That is why it is read beside occupancy, and why RevPAR combines the two.
Example
In June a 20-room hotel sells 390 room nights for ₹11,70,000 of room revenue, taxes excluded.
ADR = ₹11,70,000 ÷ 390 = ₹3,000
How Nivasik handles it
Nivasik's PMS reports and Revenue Insights read the reservations and folios themselves, so room revenue is what was actually charged to rooms, and revenue is shown against occupancy.