standard pipe diameters (D) used in calculations IP UNITS Pipe dia., inch Pipe dia., inch Pipe dia., inch 0.50 8 48 0.75 10 54 1 12 60 1.25 14 72 1.5 16 84 2 18 96 2.5 20 108 3 24 120 4 30 144 5 36 168 6 42 192 SI UNITS Pipe dia., mm Pipe dia., mm Pipe dia., mm 6 * 125 1050 8 * 150 1200 10 * 200 1350 15 250 1500 20 200 1800 25 350 2100 32 400 2400 40 450 2700 50 500 3000 65 600 3600 80 750 4200 100 900 4800 * THESE PIPE SIZES ARE NOT INCLUDED IN CALCULATORS