Yield is the only honest way to compare a home you might let with anything else you might do with the money, because it converts a rent into a rate. A ₹40,000 rent tells you nothing on its own; ₹40,000 a month against a ₹1.5 crore price is 3.2% a year gross, and that figure can sit next to a deposit rate, a bond, or a second property in a different corridor and be argued about properly. The same move works on the other side of the sum: to compare the prices rather than the rents, put two quotes on one area basis before dividing anything by either of them.
The gap between gross and net is where most of the disappointment lives. Gross yield is what gets advertised because it divides by nothing. Net yield subtracts what the property costs you to hold, and this page subtracts only the single maintenance figure you typed. A complete net figure would also take out property tax, insurance, the letting agent's cut, repairs, income tax on the rent, and — the one nobody budgets for — the months between tenants when the rent is zero and the maintenance is not.
Appreciation is treated as compound growth on the purchase price, which is the convention, and it is also the number to distrust most. It compounds, so a two-point difference in the assumed rate changes the answer more over twenty years than the entire rental income does. That is why this page starts it at zero in both columns and makes you type it: an appreciation rate supplied by the seller of the asset is not an input, it is a sales pitch.
It is also why the page has two columns rather than one. Put your real belief in B and leave A at zero, and the gap between the two lines on the chart is not a forecast — it is the exact amount of the case that rests on something nobody can check. If the case only works with the gap in it, you have learned the most useful thing this page can tell you.