256
256 is 2⁸ — the number of distinct values a single byte can hold.
Where 256 fits
Why 256 is special
256 is why so many limits in computing are 255: a byte holds 2⁸ = 256 values, and counting from zero makes the largest 255. It is the size of the extended character sets, the range of each colour channel in 24-bit images, and the reason an eight-bit game could show exactly 256 of anything before something had to give.
Same number, different meanings
How 256 is understood across different contexts — never implying one meaning because of another.
- Mathematics
256 is why so many limits in computing are 255: a byte holds 2⁸ = 256 values, and counting from zero makes the largest 255. It is the size of the extended character sets, the range of each colour channel in 24-bit images, and the reason an eight-bit game could show exactly 256 of anything before something had to give.
- Everyday life
A single byte holds 256 distinct values, so limits expressed as 255 are almost always one byte with zero counted. It is why colour channels stop at 255 and why older systems refused a 256th item.
- Technology & computing
AES-256 means a 256-bit key, giving 2²⁵⁶ possible keys — a quantity with no physical analogue, and far beyond brute force by any conceivable classical machine. The larger figure is not twice as strong as AES-128 but astronomically stronger, because the space doubles with each bit. It is chosen for margin rather than necessity: AES-128 has no practical attack either, and the main argument for 256 is resistance to a future quantum search, which would effectively halve the key length.
- Media & popular culture
Pac-Man becomes unplayable at level 256 because the level counter is a single byte: the routine that draws the bonus fruit loops once per level, and at 256 the counter reads zero and the loop overruns, filling the right half of the screen with garbage. The game has no ending — the designers never expected anyone to reach that far — so the corrupted level is the de facto finish, and the first documented perfect game through it was played in 1999.
- Geography
+256 reaches Uganda, which has among the world's youngest median ages. Its demographic profile shapes everything from schooling to mobile adoption more than most policy does.
- Religion & belief
In Ifá divination among Yoruba-speaking peoples, the sixteen principal odu pair into two hundred and fifty-six combinations (Nigeria, Benin, and the African diaspora). Sixteen taken in ordered pairs. The same arithmetic that gives a byte its range gives the corpus its size, which is a coincidence of counting in sixteens rather than a connection between the two. This is a scholarly account rather than the tradition's own framing.
Not just a mathematical number
256is also used in ways where ordinary arithmetic doesn't apply — each listed below with what genuinely does and doesn't follow from it.
- Mathematical number
A genuine quantity — its mathematical properties (prime, square, factors, and so on) are real facts about it.
A genuine quantity that ordinary arithmetic applies to — it can be prime, even, a perfect square, added to another number meaningfully, and so on.
- Measurement
Also used as a measurement — Byte.
A quantity expressed against a defined unit or standard (24 hours in a day, 60 seconds in a minute) — arithmetic is meaningful, but the specific value is a fixed convention of the measuring system, not a discovered mathematical property.
256 is part of
Factors & digit properties
- Divisors (9)
- 1, 2, 4, 8, 16, 32, 64, 128, 256
- Prime factorisation
- 2^8
- Digit sum
- 13
- Digital root
- 4
Representations
- Decimal
- 256
- Scientific notation
- 2.560 × 10^2
Roman numerals
C C L V I
Binary
1 0 0 0 0 0 0 0 0
1 × 256 + 0 × 128 + 0 × 64 + 0 × 32 + 0 × 16 + 0 × 8 + 0 × 4 + 0 × 2 + 0 × 1 = 256
Octal
4 0 0
4 × 64 + 0 × 8 + 0 × 1 = 256
Hexadecimal
1 0 0
1 × 256 + 0 × 16 + 0 × 1 = 256
Read as powers of two: 256 = 256.
In historical numeral systems
Egyptian
2 coils of rope, 5 hobbles, 6 strokes
2 × 100 + 5 × 10 + 6 × 1 = 256. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
4 vertical wedges (sixties place), 1 corner wedge + 6 vertical wedges (units place)
4 × 60 + 16 = 256. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
sigma, then nu, then stigma, marked as a numeral
sigma-nu-stigma + keraia
sigma + nu + stigma written in descending order and added — the letters carry their values wherever they stand, so this is addition, not place value.
Hebrew numerals
resh, then nun, then vav
resh-nun-vav
resh (200) + nun (50) + vav (6) = 256, written in descending order.
Maya
2 bars + 2 dots (upper, twenties place) over 3 bars + 1 dot (lower, units place)
12 × 20 + 16 = 256. Places stack vertically with the smallest at the bottom, so the upper group is worth twenty times the lower.
Systems that simply cannot reach this value are left out. Where a script needs a font most readers do not have, the reading is given instead of the glyphs — see number systems for each system in full.
Other mathematical patterns
- Deficient number
- Powerful number
Related numbers & connections
Consecutive powers of two, and consecutive units of storage history: 256 values in a byte, 512 bytes in the disk sector that file systems assumed for decades. Doubling is the only step the binary world takes.
View 512 →256 is the number of distinct values a single byte holds, which is why so many limits are the 255 that counting from zero produces.
256 appears in Numbers in culture and belief, the topic covering numbers that carry a documented cultural fact.
Mathematically related
Shares a distinctive class
- belongs toByte
why?
Strength 0.50, confidence "high".
- is associated withPowers of two
why?
Strength 0.50, confidence "high".
Numbers Around Us
- appears inCulture and belief
why?
Strength 0.50, confidence "high".
Other connections
- is associated with16777216
why?
Strength 0.50, confidence "high".
Everyday life
A single byte holds 256 distinct values, so limits expressed as 255 are almost always one byte with zero counted. It is why colour channels stop at 255 and why older systems refused a 256th item.
DocumentedEveryday lifeGeography: GlobalPeriod: 1960s–
Technology & computing
AES-256 means a 256-bit key, giving 2²⁵⁶ possible keys — a quantity with no physical analogue, and far beyond brute force by any conceivable classical machine. The larger figure is not twice as strong as AES-128 but astronomically stronger, because the space doubles with each bit. It is chosen for margin rather than necessity: AES-128 has no practical attack either, and the main argument for 256 is resistance to a future quantum search, which would effectively halve the key length.
DocumentedTechnology & computingA byte holds 2⁸ = 256 distinct values, and counting from zero makes the largest one 255. That is why so many maximums are 255 rather than 256: colour channel intensities, the largest value in an unsigned 8-bit field, and the classic arcade 'kill screen' where a counter wraps past its byte.
DocumentedTechnology & computing
Media & popular culture
Pac-Man becomes unplayable at level 256 because the level counter is a single byte: the routine that draws the bonus fruit loops once per level, and at 256 the counter reads zero and the loop overruns, filling the right half of the screen with garbage. The game has no ending — the designers never expected anyone to reach that far — so the corrupted level is the de facto finish, and the first documented perfect game through it was played in 1999.
DocumentedMedia & popular culturePeriod: 1980 game; first perfect game 1999
Geography
+256 reaches Uganda, which has among the world's youngest median ages. Its demographic profile shapes everything from schooling to mobile adoption more than most policy does.
DocumentedGeographyGeography: Uganda
Mathematics
256 = 2⁸ = 4⁴ = 16², which is why it recurs at several different levels of the same systems: sixteen hexadecimal values per digit, two hex digits per byte, 256 values per byte. The nesting is the reason hexadecimal and binary interconvert so cleanly that programmers read one as the other.
DocumentedMathematics
Religion & belief
In Ifá divination among Yoruba-speaking peoples, the sixteen principal odu pair into two hundred and fifty-six combinations (Nigeria, Benin, and the African diaspora). Sixteen taken in ordered pairs. The same arithmetic that gives a byte its range gives the corpus its size, which is a coincidence of counting in sixteens rather than a connection between the two. This is a scholarly account rather than the tradition's own framing.
Tradition / practiceReligion & beliefCulture: Ifá divination among Yoruba-speaking peoplesGeography: Nigeria, Benin, and the African diasporaPresented as belief or tradition, not as an established fact.
Common questions
Why do so many limits stop at 255 rather than 256?
Because a byte holds 256 distinct values and counting starts at zero, so the largest is 255. That is why colour channels run 0–255, why an unsigned 8-bit field maxes at 255, and why the classic arcade kill screen arrives when a level counter wraps past a byte.
Is AES-256 twice as strong as AES-128?
Far more than twice — the number of possible keys doubles with every added bit, so 256 bits gives 2¹²⁸ times as many as 128. Neither has a practical attack, and the usual argument for 256 is margin against a future quantum search, which would effectively halve any key's length.
Is 256 a prime number?
No, 256 is not prime.
What are the factors of 256?
The factors of 256 are 1, 2, 4, 8, 16, 32, 64, 128, 256.
What is 256 in Roman numerals?
256 in Roman numerals is CCLVI.
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 7 reviewer-confirmed records, sourced and reviewed before publication.
Last reviewed: 15 July 2026