Topo sheets are prepared three mainly in groups in India :
1. The million sheet, where the scale of the sheet is 1:1,000,000 or 1 cm : 10 km ; there are total of 36 of these sheets covering the entire country.
2. The quarter inch sheet has a scale of 1: 250,000 or 1 cm : 2.5 km, each of these sheets is numbered separately from A to P.
3. The one inch sheet has a scale of 1 : 50,000 or 2 cm : 1 km.
