Quick lookup
Common resolutions for each aspect ratio
Quick reference for the standard pixel dimensions at popular aspect ratios. All rows preserve the same shape — only the size changes.
| Aspect ratio | Low | Standard | High | Used for |
|---|---|---|---|---|
| 16:9 | 1280×720 | 1920×1080 | 3840×2160 | YouTube, TV, monitors |
| 9:16 | 720×1280 | 1080×1920 | 2160×3840 | TikTok, Reels, Stories |
| 4:3 | 1024×768 | 1600×1200 | 2048×1536 | iPad, old monitors |
| 1:1 | 720×720 | 1080×1080 | 2048×2048 | Instagram post, avatars |
| 3:2 | 1080×720 | 1620×1080 | 3000×2000 | DSLR photos, prints |
| 21:9 | 2560×1080 | 3440×1440 | 5120×2160 | Ultrawide, cinema |
| 4:5 | 864×1080 | 1080×1350 | 1728×2160 | Instagram portrait |
To keep an image sharp, export at the highest resolution your platform accepts, then let it downscale. Upscaling a small image always looks soft.
The basics
What is an aspect ratio?
An aspect ratio is the proportional relationship between width and height, written as W:H. A 16:9 ratio means that for every 16 units of width there are 9 of height. It describes shape independent of size — 1280×720, 1920×1080, and 3840×2160 are all 16:9. This calculator solves the missing dimension for any ratio, or works out the simplified ratio from raw pixel dimensions.
How it's calculated
The math
Finding the missing dimension
Given a ratio W:H and one dimension, scale to find the other:
- Height from width: height = width × H / W. For 1920 wide at 16:9 → 1920 × 9 / 16 = 1080
- Width from height: width = height × W / H. For 1080 tall at 16:9 → 1080 × 16 / 9 = 1920
Finding the ratio from dimensions
Divide both numbers by their greatest common divisor (GCD). 1920 and 1080 share a GCD of 120, giving 16:9. 1440×900 reduces to 8:5.
Practical guide
Which ratio for which platform?
16:9 — widescreen
The default for YouTube, TV, computer monitors, and most presentations. If unsure, use this.
9:16 — vertical
TikTok, Instagram Reels, YouTube Shorts, and Stories. Shot and viewed in portrait on phones.
1:1 — square
Classic Instagram feed posts, profile pictures, album covers. Works everywhere.
4:5 — portrait feed
Instagram's tallest feed format. Takes up more vertical space than square, grabbing more attention.
4:3 — traditional
Older monitors, iPads, many digital cameras, and document scans. More square than widescreen.
21:9 — cinematic
Ultrawide monitors and a film-like look. The monitor approximation of cinema's ~2.39:1 standard.
The trade-off
Cropping between ratios
You can't change ratio without losing something
Behind the scenes
Privacy and how it runs
Runs in your browser
Common questions
What is the height for a 1920px width at 16:9?
1080 pixels. 1920 × 9 / 16 = 1080. That's why 1920×1080 ("Full HD" or "1080p") is the most common video resolution.
How do I find the aspect ratio of a photo?
Unlock the ratio, enter the photo's pixel width and height, and the calculator reduces them to the simplest whole-number ratio. A 4032×3024 phone photo is 4:3.
What ratio is 1280×1024?
5:4. It's a slightly squarer ratio used by some older LCD monitors, not quite the same as 4:3.
What's the best resolution for YouTube?
16:9 at 1920×1080 (1080p) is the practical standard; 3840×2160 (4K) for higher quality. Both are 16:9 — same shape, more pixels.
Why do my videos have black bars?
The video's aspect ratio doesn't match the screen or player. A 4:3 video on a 16:9 screen gets bars on the sides (pillarboxing); a 21:9 film on a 16:9 screen gets bars top and bottom (letterboxing). Match the ratio to avoid them.
Related calculators
Design and media tools that pair with the aspect ratio calculator.
Last reviewed: · Methodology based on US building code standards, contractor pricing surveys, and manufacturer specifications.