All lots have not the same depth as the standard lot and the problem very often is to assign a value to a shorter or deeper lot. No absolute rule that will fit every case can be laid down, but rules have been adopted by experts which are widely used and have been proved fairly accurate. They are based on the theory that the portion of the lot nearest to the street is the most valuable part and the rear the least valuable. When you shorten a lot you take from its value, but as you still have frontage on the street the value has not been diminished proportionately with the area. Thus a lot 20 x 80 containing 1,600 square feet usually is worth more than 80 per cent of the value of a lot 20 x 100 containing 2,000 square feet.

The location of the short lot may have a great deal to do with its relative value. If the proper improvement for it would be shops or stores, it might be almost as valuable as a full depth lot; if a tenement house, it might be altogether unsuited by reason of the laws governing the erection of tenement houses, and also because of the possibility that the building would not pay an adequate return on cost.