How can one calculate Roll lengths for various diameters?

ROLL DIA
(Cms) 30 40 50 60 70 80 85 90
GSM ROLL LENGTH (Mtrs)
10 1280 2400 3800 5550 7550 9900 11250 12600
15 850 1585 2550 3675 5050 6600 7500 8400
17 760 1400 2250 3250 4450 5800 6600 7400
20 640 1190 1900 2770 3775 4950 5600 6300
25 500 1000 1500 2200 3000 4000 4500 5000
30 425 795 1265 1840 2525 3300 3700 4200
35 370 685 1085 1575 2150 2835 3600 4450
40 320 600 950 1380 1890 2480 2800 3150
45 285 530 845 1225 1680 2210 2500 2800
50 250 475 760 1100 1740 1985 2245 2520
54 240 440 705 1020 1400 1835 2075 2330
60 215 400 635 920 1260 1650 1870 2100
65 200 365 585 850 1165 1525 1730 1925
70 185 340 540 790 1080 1420 1600 1800
80 160 300 475 690 945 1240 1400 1575
90 145 265 422 615 840 1100 1245 1400
100 130 240 380 550 755 990 1124 1260
105 125 225 362 525 720 945 1070 1200