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Aspect Ratio & DPI Calculator
Exact ratios, ratio-locked resizing, PPI from real physical size, and print sizes — with curated reference tables.
Ratios reduce exactly (BigInt) — 1366×768 is honestly 683:384, near 16:9
16:9
- Decimal (w÷h)
- 1.7778
- Common name
- 16:9
- Pixels
- 2,073,600
- Megapixels
- 2.07 MP
- Orientation
- landscape
1280 × 720 px · scale 2/3
The binding side wins; the other floors to whole pixels — never a half-pixel guess.
1920 × 1080 px at 16:9 (floored)
81.6 PPI
Diagonal pixels ÷ diagonal inches — sqrt is irrational, so PPI is a float shown to one decimal (everything countable in this tool stays exact). Axes: 81.6 × 81.6 per in.
6.40 × 3.60 in · 16.3 × 9.1 cm
Convention reference points — 72/96 are screen conventions, 300 the photo-print standard. “DPI” here means image density; printers lay ink dots differently.
Common resolutions
- 640×4804:3 era baseline
- 1280×72016:9 broadcast HD
- 1920×108016:9 consumer HD
- 2560×144016:9
- 3840×216016:9, 2× Full HD per axis
- 5120×288016:9
- 7680×432016:9, 2× 4K per axis
- 3440×144043:18 — the 21:9-adjacent panel standard
Paper sizes (ISO 216 + US)
- A6105×148 mmISO 216, rounded to the mm
- A5148×210 mmISO 216
- A4210×297 mmISO 216
- A3297×420 mmISO 216
- A2420×594 mmISO 216
- US Letter215.9×279.4 mm8.5 × 11 in exactly
- US Legal215.9×355.6 mm8.5 × 14 in exactly