Rate (%),Exact (years),Rule of 70 (years),Rule of 72 (years),Rule of 69.3 (years),% Error (70)
0.5,138.9757,140.0,144.0,138.6,0.737
1.0,69.6607,70.0,72.0,69.3,0.4871
1.5,46.5555,46.6667,48.0,46.2,0.2387
2.0,35.0028,35.0,36.0,34.65,-0.008
2.5,28.071,28.0,28.8,27.72,-0.2531
3.0,23.4498,23.3333,24.0,23.1,-0.4965
3.5,20.1488,20.0,20.5714,19.8,-0.7385
4.0,17.673,17.5,18.0,17.325,-0.9788
4.5,15.7473,15.5556,16.0,15.4,-1.2176
5.0,14.2067,14.0,14.4,13.86,-1.4549
6.0,11.8957,11.6667,12.0,11.55,-1.925
7.0,10.2448,10.0,10.2857,9.9,-2.3892
8.0,9.0065,8.75,9.0,8.6625,-2.8476
9.0,8.0432,7.7778,8.0,7.7,-3.3003
10.0,7.2725,7.0,7.2,6.93,-3.7475
11.0,6.6419,6.3636,6.5455,6.3,-4.1893
12.0,6.1163,5.8333,6.0,5.775,-4.6257
13.0,5.6714,5.3846,5.5385,5.3308,-5.057
14.0,5.2901,5.0,5.1429,4.95,-5.4831
15.0,4.9595,4.6667,4.8,4.62,-5.9042
16.0,4.6702,4.375,4.5,4.3312,-6.3204
17.0,4.4148,4.1176,4.2353,4.0765,-6.7318
18.0,4.1878,3.8889,4.0,3.85,-7.1384
19.0,3.9847,3.6842,3.7895,3.6474,-7.5405
20.0,3.8018,3.5,3.6,3.465,-7.938
21.0,3.6363,3.3333,3.4286,3.3,-8.331
22.0,3.4858,3.1818,3.2727,3.15,-8.7196
23.0,3.3483,3.0435,3.1304,3.013,-9.104
24.0,3.2223,2.9167,3.0,2.8875,-9.4841
25.0,3.1063,2.8,2.88,2.772,-9.8601
26.0,2.9992,2.6923,2.7692,2.6654,-10.2321
27.0,2.9,2.5926,2.6667,2.5667,-10.6
28.0,2.8079,2.5,2.5714,2.475,-10.964
29.0,2.722,2.4138,2.4828,2.3897,-11.3242
30.0,2.6419,2.3333,2.4,2.31,-11.6806