Here is a quick reference chart on subnet size for IPv6 prefixes :
CIDR Number of IPs /128 1 /127 2 /126 4 /125 8 /124 16 /123 32 /122 64 /121 128 /120 256 /119 512 /118 1,024 /117 2,048 /116 4,096 /115 8,192 /114 16,384 /113 32,768 /112 65,536 /111 131,072 /110 262,144 /109 524,288 /108 1,048,576 /107 2,097,152 /106 4,194,304 /105 8,388,608 /104 16,777,216 /103 33,554,432 /102 67,108,864 /101 134,217,728 /100 268,435,456 /99 536,870,912 /98 1,073,741,824 /97 2,147,483,648 /96 4,294,967,296 /95 8,589,934,592 /94 17,179,869,184 /93 34,359,738,368 /92 68,719,476,736 /91 137,438,953,472 /90 274,877,906,944 /89 549,755,813,888 /88 1,099,511,627,776 /87 2,199,023,255,552 /86 4,398,046,511,104 /85 8,796,093,022,208 /84 17,592,186,044,416 /83 35,184,372,088,832 /82 70,368,744,177,664 /81 140,737,488,355,328 /80 281,474,976,710,656 /79 562,949,953,421,312 /78 1,125,899,906,842,624 /77 2,251,799,813,685,248 /76 4,503,599,627,370,496 /75 9,007,199,254,740,992 /74 18,014,398,509,481,985 /73 36,028,797,018,963,970 /72 72,057,594,037,927,940 /71 144,115,188,075,855,870 /70 288,230,376,151,711,750 /69 576,460,752,303,423,500 /68 1,152,921,504,606,847,000 /67 2,305,843,009,213,694,000 /66 4,611,686,018,427,388,000 /65 9,223,372,036,854,776,000 Residential allocation – /64 (18,446,744,073,709,552,000) /63 36,893,488,147,419,105,000 /62 73,786,976,294,838,210,000 /61 147,573,952,589,676,420,000 /60 295,147,905,179,352,850,000 /59 590,295,810,358,705,700,000 /58 1,180,591,620,717,411,500,000 /57 2,361,183,241,434,823,000,000 /56 4,722,366,482,869,646,000,000 /55 9,444,732,965,739,292,000,000 /54 18,889,465,931,478,585,000,000 /53 37,778,931,862,957,170,000,000 /52 75,557,863,725,914,340,000,000 /51 151,115,727,451,828,670,000,000 /50 302,231,454,903,657,350,000,000 /49 604,462,909,807,314,700,000,000 Business allocations – /48 (1,208,925,819,614,629,500,000,000) /47 2,417,851,639,229,259,000,000,000 /46 4,835,703,278,458,518,000,000,000 /45 9,671,406,556,917,036,000,000,000 /44 19,342,813,113,834,072,000,000,000 /43 38,685,626,227,668,145,000,000,000 /42 77,371,252,455,336,290,000,000,000 /41 154,742,504,910,672,570,000,000,000 /40 309,485,009,821,345,150,000,000,000 /39 618,970,019,642,690,200,000,000,000 /38 1,237,940,039,285,380,500,000,000,000 /37 2,475,880,078,570,761,000,000,000,000 /36 4,951,760,157,141,522,000,000,000,000 /35 9,903,520,314,283,044,000,000,000,000 /34 19,807,040,628,566,087,000,000,000,000 /33 39,614,081,257,132,168,796,771,975,168 ISP allocations – /32 (79,228,162,514,264,337,593,543,950,336) /31 158,456,325,028,528,675,187,087,900,672 /30 316,912,650,057,057,350,374,175,801,344 /29 633,825,300,114,114,700,748,351,602,688 /28 1,267,650,600,228,229,401,496,703,205,376 /27 2,535,301,200,456,458,802,993,406,410,752 /26 5,070,602,400,912,917,605,986,812,821,504 /25 10,141,204,801,825,835,211,973,625,643,008 /24 20,282,409,603,651,670,423,947,251,286,016 /23 40,564,819,207,303,340,847,894,502,572,032 /22 81,129,638,414,606,681,695,789,005,144,064 /21 162,259,276,829,213,363,391,578,010,288,128 /20 324,518,553,658,426,726,783,156,020,576,256 /19 649,037,107,316,853,453,566,312,041,152,512 /18 1,298,074,214,633,706,907,132,624,082,305,024 /17 2,596,148,429,267,413,814,265,248,164,610,048 /16 5,192,296,858,534,827,628,530,496,329,220,096 /15 10,384,593,717,069,655,257,060,992,658,440,192 /14 20,769,187,434,139,310,514,121,985,316,880,384 /13 41,538,374,868,278,621,028,243,970,633,760,768 /12 83,076,749,736,557,242,056,487,941,267,521,536 /11 166,153,499,473,114,484,112,975,882,535,043,072 /10 332,306,998,946,228,968,225,951,765,070,086,144 /9 664,613,997,892,457,936,451,903,530,140,172,288 /8 1,329,227,995,784,915,872,903,807,060,280,344,576