Powers of 2

Every power of two from 20 to 264, exact — with the computing milestones (bytes, KiB, 32-bit, 64-bit) that make them famous.

Why these numbers rule computing: every bit doubles the number of values a computer can represent, so memory sizes, address spaces, and file sizes all march up the powers of 2. That’s why a “kilobyte” of RAM is really 210 = 1,024 bytes, and why 32-bit systems max out at 232 = 4,294,967,296 addresses.
PowerExact value≈ ScientificIn computing
201
212
224
238
2416
2532
2664
27128
28256values in 1 byte
29512
2101,0241 KiB (kibibyte)
2112,048
2124,096
2138,192
21416,384
21532,768
21665,536values in 2 bytes / 64K
217131,072
218262,144
219524,288
2201,048,5761 MiB (mebibyte)
2212,097,152
2224,194,304
2238,388,608
22416,777,216
22533,554,432
22667,108,864
227134,217,728
228268,435,456
229536,870,912
2301,073,741,8241.07 × 1091 GiB (gibibyte)
2312,147,483,6482.15 × 109
2324,294,967,2964.29 × 109values in 4 bytes / IPv4 space
2338,589,934,5928.59 × 109
23417,179,869,1841.72 × 1010
23534,359,738,3683.44 × 1010
23668,719,476,7366.87 × 1010
237137,438,953,4721.37 × 1011
238274,877,906,9442.75 × 1011
239549,755,813,8885.50 × 1011
2401,099,511,627,7761.10 × 10121 TiB (tebibyte)
2412,199,023,255,5522.20 × 1012
2424,398,046,511,1044.40 × 1012
2438,796,093,022,2088.80 × 1012
24417,592,186,044,4161.76 × 1013
24535,184,372,088,8323.52 × 1013
24670,368,744,177,6647.04 × 1013
247140,737,488,355,3281.41 × 1014
248281,474,976,710,6562.81 × 1014
249562,949,953,421,3125.63 × 1014
2501,125,899,906,842,6241.13 × 10151 PiB (pebibyte)
2512,251,799,813,685,2482.25 × 1015
2524,503,599,627,370,4964.50 × 1015
2539,007,199,254,740,9929.01 × 1015
25418,014,398,509,481,9841.80 × 1016
25536,028,797,018,963,9683.60 × 1016
25672,057,594,037,927,9367.21 × 1016
257144,115,188,075,855,8721.44 × 1017
258288,230,376,151,711,7442.88 × 1017
259576,460,752,303,423,4885.76 × 1017
2601,152,921,504,606,846,9761.15 × 10181 EiB (exbibyte)
2612,305,843,009,213,693,9522.31 × 1018
2624,611,686,018,427,387,9044.61 × 1018
2639,223,372,036,854,775,8089.22 × 1018
26418,446,744,073,709,551,6161.84 × 1019values in 8 bytes

Negative powers of 2

PowerFractionDecimal
2−11/20.5
2−21/40.25
2−31/80.125
2−41/160.0625
2−51/320.03125
2−61/640.015625
2−71/1280.0078125
2−81/2560.00390625
2−91/5120.001953125
2−101/1,0240.0009765625

Need a power that isn’t here — 2100, 21000, or a fractional one like 21/3? The exponent calculator returns exact values up to 100,000 digits. The rules for combining powers are on the cheat sheet, and the same doubling math drives money too — see the compound growth table.

Sources & Further Reading