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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 16:9Insert sampleClearWidth (px)Height (px)

16:9
Decimal (w÷h)1.7778Common name16:9Pixels2,073,600Megapixels2.07 MPOrientationlandscapeBox width (px)Box height (px)

1280 × 720 px · scale 2/3

The binding side wins; the other floors to whole pixels — never a half-pixel guess.
Width knownHeight knownKnown width (px)

1920 × 1080 px at 16:9 (floored)
Physical width (in)Physical height (in)

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 .
Dots per inch

6.40 × 3.60 in · 16.3 × 9.1 cm
72 DPI96 DPI150 DPI300 DPI600 DPI

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

- VGA640 × 4804:3 era baseline
- HD 7201280 × 72016:9 broadcast HD
- Full HD 10801920 × 108016:9 consumer HD
- 1440p QHD2560 × 144016:9
- 4K UHD3840 × 216016:9, 2× Full HD per axis
- 5K5120 × 288016:9
- 8K UHD7680 × 432016:9, 2× 4K per axis
- Ultrawide 34"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

## Next door in Converter

- [Unit converter](/converters/units)
- [Color converter & contrast](/color/converter)
[All converter tools](/converters)

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