This paper proposes a cost estimation sheet supporting decision making for city planning. The urban form is represented by 30 by 30 cells on the sheet and the cost is estimated regarding population distribution, population projection, maintenance cost of road network, water supply and sewerage network, and investment for new development site. The sheet first requests its user to input current population distribution and several cost parameters. Then the sheet designates the downtown cells. A distance from closest downtown cell is calculated for each cell, which is used for cost estimation. User will be asked to finalize the spatial plan where cells are given the following labels; downtown, to be developed as new sub centers, to be disengaged. The maintenance cost is calculated by number of cells, distance from closest downtown, and population within the cell. Finally, the sheet gives how long does it take until the saving of maintenance cost by disengagement will balance the development cost of new sub centers.
