Resources around numeric data.
Numeric data and numbers can exist is a number of different flavors, some examples of terminology used include:
In essence it's the particular computing environment that defines which types exist and how to use these.
Examples:
There are many specific resources on the Internet for all sorts of considerations of data and this page only focuses on a small subset of particularly important details in regard to data communications and machine-to-machine exchange of data.
See also section on Speed for more examples of, sometimes confusing, use of bits and bytes, kilo, mega, ...
To be very clear, as abbreviations in this field can be very confusing, absolutely also for professionals who work with this daily and are not clear on what they absolutely mean (especially kilo, mega, etc when talking bytes).
For instance, in general (the whole wide world, based on the SI system):
But, in the digital world it gets a bit messier, including on which datacom layer someone is talking...
| Name | Symbol | What | Values |
|---|---|---|---|
| bit | b | Smallest unit, one bit is either a zero or a one - lowest component in computers | 2: 0 or 1 |
| nibble | (none) | 4 bits, one hexadecimal number | 16: 0-15, (0-9,A-F hex) |
| byte | B | Unit, 8 bits forms a byte. Always. | 256: 0-255 |
Unfortunately, people are NOT as stringent using 'b' for bits and 'B' for bytes and sometimes this is also mixed up - be careful.
| General Use, SI, Base 10, All Applications | Digital World, Base 2 ,Alt. Interpretation | ||||||
| Prefix Name |
Symbol [SI] |
Factor [SI, base 10] |
Power [SI, base 10] |
Base 2 | Base 1024 | Prefix [IEC] |
Symbol [IEC] |
| - | 1 | 100 (10000) | 20 (10240) | 1 c: 1 |
- | ||
| kilo | k | 1 000 | 103 (10001) | 210 (10241) | s: 1024 | kibi | Ki |
| mega | M | 1 000 000 | 106 (10002) | 220 (10242) | s: 1048576 | mebi | Mi |
| giga | G | 1 000 000 000 | 109 (10003) | 230 (10243) | s: 1073741824 | gibi | Gi |
| tera | T | 1 000 000 000 000 | 1012 (10004) | 240 (10244) | s: 1099511627776 | tebi | Ti |
| peta | P | 1 000 000 000 000 000 | 1015 (10005) | 250 (10245) | s: 1125899906842624 | pebi | Pi |
| exa | E | 1 000 000 000 000 000 000 | 1018 (10006) | 260 (10246) | s: 1152921504606846976 | exbi | Ei |
| zetta | Z | 1 000 000 000 000 000 000 000 | 1021 (10007) | 270 (10247) | s: 1180591620717411303424 | zebi | Zi |
| yotta | Y | 1 000 000 000 000 000 000 000 000 | 1024 (10008) | 280 (10248) | s: 1208925819614629174706176 | yobi | Yi |
| undef | 1 000 000 000 000 000 000 000 000 000 | 1027 (10009) | 290 (10249) | 1.2379400392854E+27 c: 1 237 940 039 285 380 274 899 124 224 |
|||
| Case | Name | Acceptance | Rec.Use | Notes | |
|---|---|---|---|---|---|
| Upper | K | Kelvin | Universally accepted standard | Yes | Temperature in unit kelvin. Unit, 'K', note that use is NOT "degree Kelvin" (symbolically °K) but simply "kelvin" (symbol K). |
| Lower | k | kilo | Universally accepted standard | Yes | Prefix (SI) for kilo, factor of 1,000 (103), 'decimal kilo' |
| Alt. | |||||
| Upper | K | kilo (base 2) | Some computing | No! | Prefix for factor 1,024 (210), 'binary kilo' (JEDEC) |
| Lower | k | kilo (base 2) | Some computing | No! | Prefix for factor 1,024 (210), 'binary kilo'. Use newer 'kibi', 'Ki', instead of 'k' |
| Lower | k | kilo (base 10) | Some computing | Yes | Prefix for factor 1,000 (103), 'decimal kilo' |
wikipedia JEDEC memory standards: Unit prefixes for semiconductor storage capacity
| Example | In (e.g.) | Interpretation | In Modern Standard |
|---|---|---|---|
| 10 KB | MS Windows File Explorer | Base 2: 10 x (210), 10240 bytes (B) | 10 KiB (kibibytes) |
| 10 kB | IT HW, Mac OS Finder, | Base 10: 10 x (10003), 10000 bytes (B) | (<-, as example) |
| 10 KiB | Some Linux | Base 2: 10 x (210), 10240 bytes (B) | (<-, as example) |
| 10 kiB | incorrect prefix | ||
| 10 kb | (E.g. when talking speeds | Base 10: 10 x (10003), 10000 bits (b) | (<-, as example) |
| 10 Kb | poor use | When talking bits, it can be even harder to determine if intention is base 2 'kilo' (kibi!) or base 10 kilo. | Either use 'kb' (kilobit,1000) or 'Kib' (kibibit, 1024) |
| 10 Kib | (E.g. when talking speeds | Base 2: 10 x (210), 10240 bits (b) | (<-, as example) |
| Area | Base | Units (e.g.) | Actual Interpretation |
|---|---|---|---|
| Memory, volatile, RAM | Base 2 | 'MB', 'GB' |
'MB' = 220,10242, = MiB 'GB' = 230, 10243, = GiB |
| Hard drives (trad., mechanical) | Base 10 | 'GB', 'TB' | 'GB' = 106,10009, 'TB' = 109, 100012. |
| Diskettes | Mix | 'MB' | A '1.44 MB' disc actually holds 1,440 KiB, 1440 x 1024, 1474560 bytes, ~1.41 MiB or ~1.47 MB10. (wikipedia: Floppy_disk) |
| Compact Disc, CD | Base 2 | 'MB' | A '700 MB' capacity disc can store around 700 MiB, 737 MB10. (wikipedia: Compact_disc, wikipedia: CD-R) |
| DVDs | Base 10 | 'GB' | A '4.7 GB (single-sided, single-layer)' DVD-R holds 4,707,319,808 bytes, around 4.4 GiB. (wikipedia: DVD) |
| USB Flash drive | Base 10 | 'GB' | A '32 GB' stick holds around 32,000,000,000 bytes, around 29.8 GiB. (wikipedia: DVD) |
https://en.wikipedia.org/wiki/Binary_prefix#Usage_notes
http://swedeteam.com/kibi/calc/
Hard specifications, physical capacity, as specified by hardware manufacturers is one thing, how presented in software can be something completely different. Example
| By / Where Shown | What you see (e.g.) | Base | Comments |
|---|---|---|---|
| By manufacturer | "32 GB, 32 billion bytes" | 10 | (A modern 32 GB USB stick), as specifiied by manufacturer, on box, on web site, around* 32,000,000,000 bytes. *) variations due to technology and manufacturing. (32 bilion bytes, 32*109 / 230 ≈ 29.8 gibibytes, GiB) |
| In Mac OS pre 10.6, Finder | "29.8 GB" | 2 | Uses older interpretation (32*109 / 230 ≈ 29.8) |
| In Mac OS 10.6 and later, Finder | "32 GB" | 10 | Conforms to SI, decimal system |
| In MS Windows, File Explorer | "29.8 GB" | 2 | Uses older interpretation |
| Modern Linux file managers | "29.8 GiB" | 10 | Uses IEC, thus also conforms to SI |
google.com/search?q=ms+windows+megabyte