1) Arithmetical increase method
In this method, a constant increase in the growth of population is added periodically and the population at the required time is determined. This method is based on an assumption that population is increasing at constant rate. This method is most suitable for old cities and towns which are stabilised.
2) Geometric Increase Method
It is based on the assumption that the percentage increase in population from decade to decade or a constant interval of time remains constant. It is suitable for larger cities.
3) Incremental Increase Method
In this method, the average of increase in population is found out by arthimetical increase method and to this is added the averageof the net incremental increase once for every future decade.
4) Decreasing Growth of Rate
This method is similar to geometrical increase method except that a changing rate of decrease is assumed rather than a constant rate of increase. The changing rate of large and old cities is generally considered to be a decreasing rate.
5) Simple Graphical Method
In this method, plotting of population of a city for the last few decades to a suitable scale on the graph paper with respect to decade and then extending the curve so obtained smoothly to forecast the future population of various decades.