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