Sum of products: {sum}. Round up to the next
multiple of 10: {next}. Check digit:{' '}
{next} − {sum} = {check}
{check === given ? `, which matches the last digit of ${value}.` : `, but ${value} ends in ${given}: this number is not valid.`}
;
};
const EAN_L = ['0001101', '0011001', '0010011', '0111101', '0100011', '0110001', '0101111', '0111011', '0110111', '0001011'];
const EAN_R = EAN_L.map(p => p.replace(/./g, c => c === '0' ? '1' : '0'));
const EAN_G = EAN_R.map(p => p.split('').reverse().join(''));
const EAN_PARITY = ['LLLLLL', 'LLGLGG', 'LLGGLG', 'LLGGGL', 'LGLLGG', 'LGGLLG', 'LGGGLL', 'LGLGLG', 'LGLGGL', 'LGGLGL'];
const leftChar = k => 3 + 7 * k + 3.5;
const rightChar = (k, halfWidth) => 3 + halfWidth + 5 + 7 * k + 3.5;
const ANATOMY = {
'ean-13': {
length: 13,
quiet: [11, 7],
encode: d => {
const parity = EAN_PARITY[d[0]];
const left = d.slice(1, 7).map((n, i) => (parity[i] === 'L' ? EAN_L : EAN_G)[n]).join('');
const right = d.slice(7).map(n => EAN_R[n]).join('');
return '101' + left + '01010' + right + '101';
},
hri: i => i === 0 ? -6 : i <= 6 ? leftChar(i - 1) : rightChar(i - 7, 42),
number: [[0, 3, 'GS1 prefix', 'Which national GS1 office issued the company prefix. Not the country the product was made in.'], [3, 12, 'Company prefix and item reference', 'The brand owner’s GS1 company prefix followed by its number for this item. Where one ends and the other begins depends on the prefix length, which you can’t tell from the digits alone.'], [12, 13, 'Check digit', 'Calculated from the other 12 digits with GS1 mod-10.']],
leftNote: 'Six digits, each seven modules wide. Each digit is drawn in one of two patterns, and the combination of patterns encodes the first digit, which has no bars of its own.'
},
'upc-a': {
length: 12,
quiet: [9, 9],
encode: d => '101' + d.slice(0, 6).map(n => EAN_L[n]).join('') + '01010' + d.slice(6).map(n => EAN_R[n]).join('') + '101',
hri: i => i === 0 ? -5 : i <= 5 ? leftChar(i) : i <= 10 ? rightChar(i - 6, 42) : 95 + 5,
extended: [[3, 10], [85, 92]],
number: [[0, 11, 'Company prefix and item reference', 'The brand owner’s GS1 company prefix followed by its number for this item.'], [11, 12, 'Check digit', 'Calculated from the other 11 digits with GS1 mod-10.']],
leftNote: 'Six digits, each seven modules wide.'
},
'ean-8': {
length: 8,
quiet: [7, 7],
encode: d => '101' + d.slice(0, 4).map(n => EAN_L[n]).join('') + '01010' + d.slice(4).map(n => EAN_R[n]).join('') + '101',
hri: i => i <= 3 ? leftChar(i) : rightChar(i - 4, 28),
number: [[0, 3, 'GS1-8 prefix', 'Which national GS1 office issued the number.'], [3, 7, 'Item reference', 'Assigned by that GS1 office for this item.'], [7, 8, 'Check digit', 'Calculated from the other 7 digits with GS1 mod-10.']],
leftNote: 'Four digits, each seven modules wide.'
},
'upc-e': {
length: 8,
quiet: [9, 7],
encode: d => {
const forZero = ['GGGLLL', 'GGLGLL', 'GGLLGL', 'GGLLLG', 'GLGGLL', 'GLLGGL', 'GLLLGG', 'GLGLGL', 'GLGLLG', 'GLLGLG'][d[7]];
const parity = d[0] === 0 ? forZero : forZero.replace(/./g, c => c === 'G' ? 'L' : 'G');
return '101' + d.slice(1, 7).map((n, i) => (parity[i] === 'L' ? EAN_L : EAN_G)[n]).join('') + '010101';
},
hri: i => i === 0 ? -5 : i <= 6 ? leftChar(i - 1) : 51 + 4,
guards: () => [[0, 3], [45, 51]],
structure: () => [['Start guard', 0, 3, 'Three modules (bar, space, bar) that tell the scanner where the symbol starts and how wide one module is.'], ['Six digits', 3, 45, 'Each digit is seven modules wide and drawn in one of two patterns. The combination of patterns encodes the number system and the check digit, which have no bars of their own.'], ['End guard', 45, 51, 'Six modules that mark the end of the symbol.']],
number: [[0, 1, 'Number system', 'Always 0 or 1.'], [1, 7, 'Zero-suppressed digits', 'The company prefix and item reference with their zeros removed. The last of the six says where the zeros go back.'], [7, 8, 'Check digit', 'The check digit of the full 12-digit UPC-A.']]
}
};
ANATOMY.isbn = {
...ANATOMY['ean-13'],
number: [[0, 3, 'Prefix', '978 or 979, which mark the number as a book.'], [3, 12, 'Registration group, registrant and publication', 'The language area or country, the publisher, and the edition. Each part varies in length, which is what the hyphens in a printed ISBN show.'], [12, 13, 'Check digit', 'Calculated from the other 12 digits with GS1 mod-10.']]
};
ANATOMY.issn = {
...ANATOMY['ean-13'],
number: [[0, 3, 'Prefix', '977, which marks the number as a serial publication.'], [3, 10, 'ISSN', 'The first seven digits of the ISSN. Its own check digit is left out.'], [10, 12, 'Variant', 'Usually 00. Publishers change it for a special issue or a price change.'], [12, 13, 'Check digit', 'Calculated from the other 12 digits with GS1 mod-10.']]
};
const Anatomy = ({type, value, plain}) => {
const spec = ANATOMY[type];
const digits = String(value).split('').map(Number);
if (!spec || digits.length !== spec.length || digits.some(isNaN)) {
return
Can’t draw {type} for “{value}”.
;
}
const modules = spec.encode(digits);
const n = modules.length;
const half = (n - 11) / 2;
const guards = spec.guards ? spec.guards() : [[0, 3], [3 + half, 8 + half], [n - 3, n]];
const tall = [...guards, ...spec.extended || []];
const isTall = m => tall.some(([a, b]) => m >= a && m < b);
const M = 4;
const [qL, qR] = spec.quiet;
const x = m => (qL + m) * M;
const width = (qL + n + qR) * M;
const labelTop = plain ? 0 : 30, barTop = labelTop + 6, barH = 70, guardH = 76, hriY = barTop + guardH + 4, labelBottom = hriY + 6;
const bottomBracket = labelBottom + 8, height = plain ? labelBottom : bottomBracket + 22;
const bars = [];
for (let m = 0; m < n; m++) {
if (modules[m] !== '1') continue;
let end = m;
while (modules[end + 1] === '1') end++;
bars.push();
m = end;
}
const structure = spec.structure ? spec.structure() : [['Start guard', 0, 3, 'Three modules (bar, space, bar) that tell the scanner where the symbol starts and how wide one module is.'], ['Left half', 3, 3 + half, spec.leftNote], ['Center guard', 3 + half, 8 + half, 'Five modules that separate the two halves. Scanners decode each half on its own, then join them.'], ['Right half', 8 + half, n - 3, 'The remaining digits, each seven modules wide, always drawn from the same set of patterns.'], ['End guard', n - 3, n, 'Three modules that mark the end of the symbol.']];
const numberSegs = spec.number.map(([a, b, name, meaning]) => [name, spec.hri(a) - 3.5, spec.hri(b - 1) + 3.5, meaning]);
const legend = [...structure, ...numberSegs];
const bracket = (key, x1, x2, y, up) => {
const t = up ? y - 4 : y + 4;
return ;
};
const marker = (key, label, cx, y) => {label};
const label = <>
{}
{bars}
{digits.map((d, i) => {d})}
;
if (plain) {
return ;
}
return
{legend.map(([name, , , meaning]) =>
{name}. {meaning}
)}
;
};
const C128 = [[2, 1, 2, 2, 2, 2], [2, 2, 2, 1, 2, 2], [2, 2, 2, 2, 2, 1], [1, 2, 1, 2, 2, 3], [1, 2, 1, 3, 2, 2], [1, 3, 1, 2, 2, 2], [1, 2, 2, 2, 1, 3], [1, 2, 2, 3, 1, 2], [1, 3, 2, 2, 1, 2], [2, 2, 1, 2, 1, 3], [2, 2, 1, 3, 1, 2], [2, 3, 1, 2, 1, 2], [1, 1, 2, 2, 3, 2], [1, 2, 2, 1, 3, 2], [1, 2, 2, 2, 3, 1], [1, 1, 3, 2, 2, 2], [1, 2, 3, 1, 2, 2], [1, 2, 3, 2, 2, 1], [2, 2, 3, 2, 1, 1], [2, 2, 1, 1, 3, 2], [2, 2, 1, 2, 3, 1], [2, 1, 3, 2, 1, 2], [2, 2, 3, 1, 1, 2], [3, 1, 2, 1, 3, 1], [3, 1, 1, 2, 2, 2], [3, 2, 1, 1, 2, 2], [3, 2, 1, 2, 2, 1], [3, 1, 2, 2, 1, 2], [3, 2, 2, 1, 1, 2], [3, 2, 2, 2, 1, 1], [2, 1, 2, 1, 2, 3], [2, 1, 2, 3, 2, 1], [2, 3, 2, 1, 2, 1], [1, 1, 1, 3, 2, 3], [1, 3, 1, 1, 2, 3], [1, 3, 1, 3, 2, 1], [1, 1, 2, 3, 1, 3], [1, 3, 2, 1, 1, 3], [1, 3, 2, 3, 1, 1], [2, 1, 1, 3, 1, 3], [2, 3, 1, 1, 1, 3], [2, 3, 1, 3, 1, 1], [1, 1, 2, 1, 3, 3], [1, 1, 2, 3, 3, 1], [1, 3, 2, 1, 3, 1], [1, 1, 3, 1, 2, 3], [1, 1, 3, 3, 2, 1], [1, 3, 3, 1, 2, 1], [3, 1, 3, 1, 2, 1], [2, 1, 1, 3, 3, 1], [2, 3, 1, 1, 3, 1], [2, 1, 3, 1, 1, 3], [2, 1, 3, 3, 1, 1], [2, 1, 3, 1, 3, 1], [3, 1, 1, 1, 2, 3], [3, 1, 1, 3, 2, 1], [3, 3, 1, 1, 2, 1], [3, 1, 2, 1, 1, 3], [3, 1, 2, 3, 1, 1], [3, 3, 2, 1, 1, 1], [3, 1, 4, 1, 1, 1], [2, 2, 1, 4, 1, 1], [4, 3, 1, 1, 1, 1], [1, 1, 1, 2, 2, 4], [1, 1, 1, 4, 2, 2], [1, 2, 1, 1, 2, 4], [1, 2, 1, 4, 2, 1], [1, 4, 1, 1, 2, 2], [1, 4, 1, 2, 2, 1], [1, 1, 2, 2, 1, 4], [1, 1, 2, 4, 1, 2], [1, 2, 2, 1, 1, 4], [1, 2, 2, 4, 1, 1], [1, 4, 2, 1, 1, 2], [1, 4, 2, 2, 1, 1], [2, 4, 1, 2, 1, 1], [2, 2, 1, 1, 1, 4], [4, 1, 3, 1, 1, 1], [2, 4, 1, 1, 1, 2], [1, 3, 4, 1, 1, 1], [1, 1, 1, 2, 4, 2], [1, 2, 1, 1, 4, 2], [1, 2, 1, 2, 4, 1], [1, 1, 4, 2, 1, 2], [1, 2, 4, 1, 1, 2], [1, 2, 4, 2, 1, 1], [4, 1, 1, 2, 1, 2], [4, 2, 1, 1, 1, 2], [4, 2, 1, 2, 1, 1], [2, 1, 2, 1, 4, 1], [2, 1, 4, 1, 2, 1], [4, 1, 2, 1, 2, 1], [1, 1, 1, 1, 4, 3], [1, 1, 1, 3, 4, 1], [1, 3, 1, 1, 4, 1], [1, 1, 4, 1, 1, 3], [1, 1, 4, 3, 1, 1], [4, 1, 1, 1, 1, 3], [4, 1, 1, 3, 1, 1], [1, 1, 3, 1, 4, 1], [1, 1, 4, 1, 3, 1], [3, 1, 1, 1, 4, 1], [4, 1, 1, 1, 3, 1], [2, 1, 1, 4, 1, 2], [2, 1, 1, 2, 1, 4], [2, 1, 1, 2, 3, 2], [2, 3, 3, 1, 1, 1, 2]];
const C39_CHARS = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ-. $/+%';
const C39 = [0x034, 0x121, 0x061, 0x160, 0x031, 0x130, 0x070, 0x025, 0x124, 0x064, 0x109, 0x049, 0x148, 0x019, 0x118, 0x058, 0x00d, 0x10c, 0x04c, 0x01c, 0x103, 0x043, 0x142, 0x013, 0x112, 0x052, 0x007, 0x106, 0x046, 0x016, 0x181, 0x0c1, 0x1c0, 0x091, 0x190, 0x0d0, 0x085, 0x184, 0x0c4, 0x0a8, 0x0a2, 0x08a, 0x02a];
const C39_STAR = 0x094;
const I25 = ['NNWWN', 'WNNNW', 'NWNNW', 'WWNNN', 'NNWNW', 'WNWNN', 'NWWNN', 'NNNWW', 'WNNWN', 'NWNWN'];
const C93 = [0x114, 0x148, 0x144, 0x142, 0x128, 0x124, 0x122, 0x150, 0x112, 0x10a, 0x1a8, 0x1a4, 0x1a2, 0x194, 0x192, 0x18a, 0x168, 0x164, 0x162, 0x134, 0x11a, 0x158, 0x14c, 0x146, 0x12c, 0x116, 0x1b4, 0x1b2, 0x1ac, 0x1a6, 0x196, 0x19a, 0x16c, 0x166, 0x136, 0x13a, 0x12e, 0x1d4, 0x1d2, 0x1ca, 0x16e, 0x176, 0x1ae, 0x126, 0x1da, 0x1d6, 0x132, 0x15e];
const code93 = text => {
const values = [...text].map(c => C39_CHARS.indexOf(c));
const weighted = (vs, max) => vs.reduceRight((acc, v, i) => acc + v * ((vs.length - 1 - i) % max + 1), 0) % 47;
const c = weighted(values, 20);
const k = weighted([...values, c], 15);
const modules = [47, ...values, c, k, 47].map(v => C93[v].toString(2).padStart(9, '0')).join('') + '1';
const widths = [];
for (let i = 0; i < modules.length; ) {
let j = i;
while (modules[j] === modules[i]) j++;
widths.push(j - i);
i = j;
}
const n = values.length;
const name = v => C39_CHARS[v] || `value ${v}`;
return {
widths,
hri: text,
segments: [['Start character', 0, 9, 'Marks the start. Scanners don’t send it.'], ['Data', 9, 9 * (n + 1), 'Each character is 9 modules: three bars and three spaces, each 1 to 4 modules wide.'], ['Check character C', 9 * (n + 1), 9 * (n + 2), `Mod-47 over the data, with weights 1 to 20. Here, ${name(c)}.`], ['Check character K', 9 * (n + 2), 9 * (n + 3), `Mod-47 over the data and C, with weights 1 to 15. Here, ${name(k)}.`], ['Stop', 9 * (n + 3), 9 * (n + 4) + 1, 'The stop character, then a single-module bar that ends the symbol.']]
};
};
const code39 = text => {
const chars = [...text];
const check = C39_CHARS[chars.reduce((sum, c) => sum + C39_CHARS.indexOf(c), 0) % 43];
const element = bits => Array.from({
length: 9
}, (_, i) => bits >> 8 - i & 1 ? 3 : 1);
const parts = [C39_STAR, ...chars.map(c => C39[C39_CHARS.indexOf(c)]), C39[C39_CHARS.indexOf(check)], C39_STAR];
const widths = [];
parts.forEach((bits, i) => {
widths.push(...element(bits));
if (i < parts.length - 1) widths.push(1);
});
const char = 16;
const n = parts.length;
return {
widths,
hri: text + check,
segments: [['Start character', 0, 15, 'An asterisk. It marks the start, and scanners don’t send it.'], ['Data', char, char * (n - 2) - 1, 'Each character is nine elements, five bars and four spaces, three of them wide. A narrow gap separates characters.'], ['Check character', char * (n - 2), char * (n - 1) - 1, `Optional. The mod-43 check for this data is ${check}.`], ['Stop character', char * (n - 1), char * n - 1, 'Another asterisk, which marks the end.']]
};
};
const code128Values = (text, gs1) => {
const digitsAt = i => {
let n = 0;
while ((/\d/).test(text[i + n] || '')) n++;
return n;
};
let set = digitsAt(0) >= 4 ? 'C' : 'B';
const values = [set === 'C' ? 105 : 104];
if (gs1) values.push(102);
for (let i = 0; i < text.length; ) {
if (text[i] === '\x1d') {
values.push(102);
i += 1;
continue;
}
if (set === 'C') {
if (digitsAt(i) >= 2) {
values.push(Number(text.slice(i, i + 2)));
i += 2;
} else {
values.push(100);
set = 'B';
}
} else if (digitsAt(i) >= 4 && digitsAt(i) % 2 === 0) {
values.push(99);
set = 'C';
} else {
values.push(text.charCodeAt(i) - 32);
i += 1;
}
}
return values;
};
const code128 = (text, gs1) => {
const data = gs1 ? gs1Text(text) : text;
const values = code128Values(data, gs1);
const check = values.reduce((sum, v, i) => sum + v * (i || 1), 0) % 103;
const widths = [...values, check, 106].flatMap(v => C128[v]);
const head = gs1 ? 22 : 11;
const end = values.length * 11;
const startSet = values[0] === 105 ? 'C' : 'B';
const startNote = startSet === 'C' ? 'The first characters are digits, packed two to a character.' : 'The first characters are text. The start code also counts toward the check.';
return {
widths,
hri: text,
segments: [[`Start code ${startSet}`, 0, 11, startNote], ...gs1 ? [['FNC1', 11, 22, 'A special character that marks the barcode as GS1-128. Scanners don’t send it as data.']] : [], ['Data', head, end, gs1 ? 'Each character is 11 modules: three bars and three spaces. Digits are packed two to a character in code set C, then a switch to code set B handles the letters.' : 'Each character is 11 modules: three bars and three spaces, each 1 to 4 modules wide.'], ['Check character', end, end + 11, `Mod-103 check, value ${check}. Scanners verify it, then drop it.`], ['Stop', end + 11, end + 24, 'Thirteen modules, ending in a final bar.']]
};
};
const itf = (digits, wide = 2.5) => {
const widths = [1, 1, 1, 1];
for (let i = 0; i < digits.length; i += 2) {
const bars = I25[digits[i]], spaces = I25[digits[i + 1]];
for (let k = 0; k < 5; k++) widths.push(bars[k] === 'W' ? wide : 1, spaces[k] === 'W' ? wide : 1);
}
widths.push(wide, 1, 1);
const pair = 2 * (3 + 2 * wide);
const end = 4 + pair * (digits.length / 2);
return {
widths,
hri: digits,
segments: [['Start', 0, 4, 'Four narrow elements: bar, space, bar, space.'], ['Digit pairs', 4, end, 'Each pair of digits shares five bars and five spaces. The first digit sets which bars are wide, the second which spaces are wide.'], ['Stop', end, end + wide + 2, 'A wide bar, a narrow space and a narrow bar.']]
};
};
const GS1_AI_NAMES = {
'00': ['SSCC', 'The serial shipping container code: an 18-digit number for one pallet or parcel.'],
'01': ['GTIN', 'The product’s 14-digit GTIN.'],
10: ['Batch or lot', 'Up to 20 characters. Variable length, so it comes last or is followed by a separator.'],
11: ['Production date', 'YYMMDD.'],
15: ['Best before date', 'YYMMDD.'],
17: ['Expiry date', 'YYMMDD.'],
21: ['Serial number', 'Up to 20 characters.'],
37: ['Count', 'How many trade items the unit contains.']
};
const LINEAR = {
'code-39': {
quiet: 10,
encode: v => code39(v)
},
'code-93': {
quiet: 10,
encode: v => code93(v)
},
'code-128': {
quiet: 10,
encode: v => code128(v, false)
},
'gs1-128': {
quiet: 10,
encode: v => code128(v, true),
numbers: hri => [...hri.matchAll(/\((\d{2,4})\)[^(]*/g)].map(m => {
const [name, meaning] = GS1_AI_NAMES[m[1]] || [`AI ${m[1]}`, ''];
return [m.index, m.index + m[0].length, `(${m[1]}) ${name}`, meaning];
})
},
'interleaved-2-of-5': {
quiet: 10,
encode: v => itf(v)
},
'itf-14': {
quiet: 10,
bearer: true,
encode: v => itf(v),
numbers: () => [[0, 1, 'Indicator digit', 'The packaging level. 1 to 8 mean a case or other grouping of the same item.'], [1, 13, 'Item number', 'Often the first 12 digits of the item’s own GTIN-13, but not always.'], [13, 14, 'Check digit', 'GS1 mod-10, calculated over all 14 digits.']]
}
};
const Linear = ({type, value, plain}) => {
const spec = LINEAR[type];
if (!spec || !value) return
;
};
export const type_0 = "code-128"
Code 128 is the most widely used general-purpose linear barcode. It can encode any text a keyboard can type, and it packs digits two to a character, so it's compact for both.
Scan or paste a barcode and see every part of it.
Generate a valid barcode from fields.
## Where you'll see it
* **Shipping labels.** Parcel carriers' tracking numbers are commonly Code 128.
* **Logistics labels** in the GS1 form, [GS1-128](/reference/barcode-types/gs1-128).
* **Inventory, asset and document labels**, wherever a business needs letters as well as numbers.
## Anatomy
### Characters
Every character is 11 modules wide, made of three bars and three spaces, each 1 to 4 modules wide. There are 107 different characters: 103 for data and control, three start codes, and a stop.
### Three code sets
The same 103 characters mean different things in each of three code sets:
| Code set | Contains | Use it for |
| - | - | - |
| A | Uppercase letters, digits, punctuation and control characters | Data with control characters, such as a tab |
| B | Uppercase and lowercase letters, digits and punctuation | Ordinary text |
| C | The pairs of digits 00 to 99 | Numbers, at two digits per character |
The start code chooses the first code set, and special characters switch between them part way through. An encoder picks the shortest combination, so `ABC12345678` is usually encoded as letters in code set B, then the digits in pairs in code set C.
You never see any of this in the data. A scanner returns the text, not the code sets.
### Size and quiet zones
Code 128 has no fixed size; each application sets its own. The quiet zones are at least 10 modules on each side.
## Check character
Every Code 128 barcode ends with a check character, calculated with mod-103 from the start code and every character after it. For `ZipZap`, it's the character with value 40.
Scanners verify it and then drop it, so it's never printed or sent, and you only need it to draw a barcode. The calculation is worked through in [Check digits](/reference/check-digits#code-128-mod-103).
## Variants and related types
* **[GS1-128](/reference/barcode-types/gs1-128)**: Code 128 with a special character at the start that marks GS1 data.
* **[Code 39](/reference/barcode-types/code-39)**: older, simpler and less dense, with uppercase letters only.
* **[Code 93](/reference/barcode-types/code-93)**: a denser successor to Code 39 that never displaced Code 128.
## Gotchas
* **A barcode that's too long to scan.** Long text makes a wide barcode. Past a certain width, phone cameras and handheld scanners can't fit it in view. Consider a QR code for long data.
* **Invisible characters in the data.** Code set A can carry control characters, such as a tab or a line break, that won't be visible when you print the scan. See [invisible characters](/reference/scan-vs-printed-number#invisible-characters).
* **A Code 128 barcode that's really GS1 data.** If it starts with digits like `01` or `00` and the scanner reports GS1-128, parse it as GS1 data, not as plain text.
## Scanning it in your app
```swift theme={null}
ScanField("Tracking number", text: $tracking)
.barcodeTypes(.code128)
.validate(.matches(/^[A-Z0-9]{10,22}$/))
```
Code 128 accepts almost any text, so a pattern is the best way to make sure a scan is the kind of value you expect. See [Validation](/sdk/modifiers/validation).
## Specification
* ISO/IEC 15417: the Code 128 barcode specification.
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