Below is a practical “field guide” to the aspect-ratios you’re most likely to meet in the wild, grouped by the media where each ratio is standard or at least very common. (It’s not mathematically exhaustive—ratios are infinite—but it does cover every major production, display, and print standard you’ll encounter in filmmaking, video, photography, graphic design, publishing, and social media.)
How to Read & Use This List
Match the medium first. Choose from Sections 1–5 above depending on whether you’re mastering a film, formatting a book, spec-ing a monitor, or designing social-media graphics.
Check downstream workflows. A 2.39 ∶ 1 DCP delivered to TV will be letterboxed inside 16:9 unless you create a 1.78 blow-up. Likewise, a 9:16 TikTok will pillar-box on YouTube unless reframed.
Mind pixel divisibility. If you need dimensions divisible by 64 (e.g., for diffusion models or GPU tile sizes), multiply both parts of the ratio until each side lands on a multiple of 64—e.g., 16 : 9 → 1024 × 576, 1920 × 1080, 2560 × 1440, etc.
Favor even numbers in print. Print shops often round to the nearest 1 ⁄ 8-inch or to millimeters, so choose trim sizes that fit standard paper and don’t require odd crop marks.
Quick-reference “Greatest Hits”
1 : 1 — Square (Instagram grid, album art)
4 : 3 — Legacy TV, older DSLRs, iPad screens
3 : 2 — 35 mm photo & full-frame mirrorless
16 : 9 — HDTV, YouTube, most phones in landscape
2.39 : 1 — Modern cinema widescreen
9 : 16 — Mobile-first vertical video