print-sizings

Standard print sizes as typed constants, plus helpers to turn any size and DPI into pixel dimensions.

• 98 built-in sizes: landscape, portrait, square, panoramic, and ISO A0–A4
• Any DPI, with presets for 150, 300 and 600
• Custom sizes work too: pass any { width, height } in inches
• Fully typed: size ids autocomplete, and a typo is a compile error
• No dependencies, ESM-only, tree-shakeable, under 3 kB gzipped

Install

npm install print-sizings

Requires Node 22+ or any modern bundler. The package is ESM-only. From CommonJS on Node 22+, require('print-sizings') works (via require(esm)).

Usage

import { DPI, toPixels, getPrintSize, listPrintSizes } from 'print-sizings';

toPixels('10x8', DPI.STANDARD);
// → { width: 3000, height: 2400, dpi: 300 }

toPixels('a4-portrait', DPI.HIGH);
// → { width: 4961, height: 7016, dpi: 600 }

// Any DPI
toPixels('16x20', 240);
// → { width: 3840, height: 4800, dpi: 240 }

// Custom size in inches
toPixels({ width: 5, height: 7 }, DPI.LOW);
// → { width: 750, height: 1050, dpi: 150 }

getPrintSize('8x10');
// → { id: '8x10', category: 'portrait', orientation: 'portrait',
//     label: '8 × 10 in', width: 8, height: 10 }

// Build a picker: every square size with its pixel size at 300 DPI
listPrintSizes({ category: 'square' }).map((size) => ({
  ...size,
  pixels: toPixels(size, DPI.STANDARD),
}));

API

Constants

| Export | Description | | ---------------------------------------------------------------------- | -------------------------------------------------- | | PRINT_SIZES | Every size as a flat, frozen array of PrintSize | | PRINT_SIZES_BY_CATEGORY | { landscape, portrait, square, panoramic } | | LANDSCAPE_SIZES, PORTRAIT_SIZES, SQUARE_SIZES, PANORAMIC_SIZES | Each category on its own | | PRINT_CATEGORIES | ['landscape', 'portrait', 'square', 'panoramic'] | | DPI | { LOW: 150, STANDARD: 300, HIGH: 600 } | | DPI_PRESETS | [150, 300, 600] | | MM_PER_INCH | 25.4 |

toPixels(size, dpi = 300, options?)

Returns { width, height, dpi } in whole pixels.

• size: a size id ('10x8'), a PrintSize object, or any { width, height } in inches
• dpi: any positive, finite number. Defaults to 300.
• options.rounding: 'round' (the default), 'floor' or 'ceil'

Throws a RangeError for an invalid DPI, and a TypeError for an unknown id.

toPixelsAtPresets(size, options?)

Returns the pixel dimensions at all three presets, keyed by DPI: { 150: {...}, 300: {...}, 600: {...} }.

getPrintSize(id)

Looks up a size by id. With a literal id the return type is exact. With an arbitrary string the return type is PrintSize | undefined.

isPrintSizeId(value)

Type guard that narrows a string to PrintSizeId.

listPrintSizes(filter?)

Lists sizes, optionally filtered. Both filter fields take a single value or an array.

listPrintSizes({ category: 'panoramic', orientation: 'portrait' }); // the tall panoramics
listPrintSizes({ category: ['landscape', 'square'] });

toMillimetres(size)

Converts a size id or { width, height } in inches to millimetres. The result is not rounded.

Types

PrintSize, PrintSizeId, PrintCategory, Orientation, IsoPaperSize, Dimensions, PixelDimensions, DpiPreset, Rounding, ToPixelsOptions, PrintSizeFilter.

interface PrintSize {
  id: PrintSizeId; // '10x8', '8x10', 'a4-portrait', …
  category: PrintCategory; // 'landscape' | 'portrait' | 'square' | 'panoramic'
  orientation: Orientation; // 'landscape' | 'portrait' | 'square' (from the dimensions)
  label: string; // '10 × 8 in', 'A4 (portrait)'
  width: number; // inches
  height: number; // inches
  paper?: IsoPaperSize; // 'A0' … 'A4', ISO sizes only
}

Sizes

Every dimension is in inches and written width × height. An id is {width}x{height}, so 10x8 is landscape and 8x10 is portrait. The panoramic category holds both orientations. Use orientation to tell them apart.

ISO A-series sizes are calculated from their exact millimetre dimensions (A4 = 210 × 297 mm), so they print at the standard pixel sizes: A4 at 300 DPI is 2480 × 3508.

landscape: 10x7, 10x8, 12x10, 12x8, 12x9, 14x10, 14x11, 15x10, 15x12, 16x11, 16x12, 18x12, 20x16, 24x16, 24x20, 30x20, 30x24, 36x24, 40x30, 48x36, 60x40, a4-landscape, a3-landscape, a2-landscape, a1-landscape, a0-landscape

portrait: 7x10, 8x10, 10x12, 8x12, 9x12, 10x14, 11x14, 10x15, 12x15, 11x16, 12x16, 12x18, 16x20, 16x24, 20x24, 20x30, 24x30, 24x36, 30x40, 36x48, 40x60, a4-portrait, a3-portrait, a2-portrait, a1-portrait, a0-portrait

square: 8x8, 9x9, 10x10, 11x11, 12x12, 14x14, 15x15, 16x16, 20x20, 24x24, 30x30, 40x40

panoramic: 12x6, 6x12, 16x8, 8x16, 18x10, 10x18, 20x8, 8x20, 20x10, 10x20, 21x8, 8x21, 24x10, 10x24, 24x13, 13x24, 25x10, 10x25, 26x7, 7x26, 26x12, 12x26, 28x10, 10x28, 28x11, 11x28, 30x10, 10x30, 30x11, 11x30, 30x12, 12x30, 30x15, 15x30

Choosing a DPI

| DPI | Use for | | -------------------- | ---------------------------------------------- | | 150 (DPI.LOW) | Large posters and banners seen from a distance | | 300 (DPI.STANDARD) | Photo and art prints. The usual default. | | 600 (DPI.HIGH) | Fine art, line art, and small text |

Contributing

npm install
npm run lint        # oxlint (npm run lint:fix to autofix)
npm run format      # oxfmt (npm run format:check to verify only)
npm run typecheck   # tsc
npm test            # vitest
npm run check       # all of the above, plus build and package lint (publint + attw)
npm run changeset   # describe your change for the changelog

See RELEASING.md for how releases work.

License

MIT © James Porter