Aspect Ratio Calculator
Calculate and convert aspect ratios for images and video. Lock ratios, use platform presets for Instagram, YouTube, TikTok, and more. Shows megapixels and orientation.
Dimensions
Preview
Aspect Ratio
16:9
Orientation
Landscape
Dimensions
1920 × 1080
Megapixels
2.07 MP
Common Aspect Ratios
Platform Presets
About aspect ratios
An aspect ratio is the proportional relationship between an image's width and height. Locking the aspect ratio maintains the ratio when you change either dimension. Common ratios include 16:9 (widescreen), 4:3 (standard), and 1:1 (square).
What Aspect Ratio Do I Actually Need?
It depends on where the image will live. YouTube thumbnails are 1280 x 720 (16:9). Instagram square posts are 1080 x 1080 (1:1). Instagram Stories and TikTok are 1080 x 1920 (9:16, vertical). Twitter/X timeline images are 1200 x 675 (16:9). Pick the platform first, then size the canvas to match - cropping a 16:9 video into a 9:16 Reel after the fact loses the top and bottom of every shot.
If your tool input shows a ratio like 17:9 or 853:480 instead of one of the clean ratios, the image is slightly off-spec for the platform you intended. The calculator simplifies any width and height into the smallest whole-number ratio using the greatest common divisor, then matches it against standard presets like 16:9, 4:3, 21:9 and 1:1. A perfectly square 1024 x 1024 will read 1:1; an Instagram Reel-bound 1080 x 1920 reads 9:16.
Locking the Ratio While Resizing
Toggle the lock icon and the calculator will keep the aspect ratio fixed while you change either dimension. Type a new width and the height auto-adjusts; type a new height and the width follows. This is the right way to scale a 1920 x 1080 video frame down to 1280 x 720 for a thumbnail without distorting people's faces.
Without the lock you can break the ratio on purpose, which is occasionally useful (squashing a 16:9 graphic into 1200 x 675 for a Twitter card lops a thin strip off the height because they are both 16:9 already, but a 1500 x 500 banner crop is genuinely a different ratio). The megapixel readout helps you spot when a resize has pushed an image below useful resolution: anything under 0.5 megapixels (roughly 800 x 625) starts to look soft on retina screens.
Common Resolutions for Print and Video
1920 x 1080 is the long-standing Full HD video standard at 16:9. 4K UHD is 3840 x 2160 (also 16:9, exactly four times the pixels of Full HD). Cinematic 21:9 widescreen typically renders at 2560 x 1080 or 3440 x 1440. For print, A4 lands at roughly 2480 x 3508 pixels at 300 DPI, which is closer to a 5:7 ratio than to any of the screen presets.
A common error is assuming Instagram posts are still 1080 x 1080 - the platform now accepts 1080 x 1350 (4:5 portrait) which gets considerably more screen real estate in the feed. The [colour palette generator](/colour-palette-generator) and [font pair suggester](/font-pair-suggester) can help finalise the look once you have committed to the right canvas size.
Frequently Asked Questions
What does 16:9 actually mean?
16:9 means for every 16 units of width, the image is 9 units tall. So a 16:9 image at 1920 wide is 1080 tall (1920 divided by 16, multiplied by 9). It is the dominant ratio for modern TVs, YouTube videos and most computer monitors. The 4:3 ratio it replaced was the standard for older CRT TVs.
How do I convert a 4:3 image to 16:9 without distortion?
You either crop or pad. Cropping a 1024 x 768 (4:3) image to 16:9 means cutting 96 pixels off the top or bottom (1024 x 576). Padding adds 192 pixels of background colour on left and right, giving a 1365 x 768 result. Distortion - simply stretching - is what to avoid because it makes circles oval and people look squashed.
What aspect ratio is best for Instagram?
Instagram now supports four formats: 1:1 (square 1080 x 1080), 4:5 (portrait 1080 x 1350), 9:16 (Stories and Reels at 1080 x 1920), and 1.91:1 (landscape 1080 x 566). Portrait 4:5 takes the most space in the feed and tends to perform best for static posts. Reels and Stories must be 9:16 or they get letterboxed.
Why does my image look different on TikTok versus Instagram?
TikTok crops the visible area to 1080 x 1920 (full 9:16) but the safe zone where text and faces will not be hidden by UI is closer to 1080 x 1350. Instagram Reels apply a similar safe zone. If you mastered for one platform without keeping critical content within the centre 60% of the frame, important elements may be hidden behind buttons or captions on the other.
Related Tools
Colour Palette Generator
Generate beautiful colour palettes instantly. Choose from random, monochromatic, analogous, complementary, triadic, pastel, and more. Lock colours, copy hex codes, download as PNG.
Colour Contrast Checker
Check if your text and background colours meet WCAG accessibility standards (AA & AAA). Auto-fix suggestions included
Font Pair Suggester
Select a heading font from 20 Google Fonts. Get recommended complementary body fonts with live preview and CSS import code.