Aspect ratio calculator
Type a width and height to get the simplified aspect ratio, or pick a ratio and one side to get the other. Everything runs in your browser and nothing is uploaded. Common sizes for video, social posts, thumbnails and link previews are listed below.
Find the ratio
- As a decimal
- 1.778 : 1
- Standard ratio
- Matches 16:9
- Orientation
- Landscape (wider than tall)
Resize to a ratio
Rounded to whole pixels; the exact value is 720.00.
Common sizes
| Use | Ratio | Size (px) | Load into the calculator |
|---|---|---|---|
| Full HD video, YouTube | 16:9 | 1,920 × 1,080 | Try it |
| YouTube thumbnail | 16:9 | 1,280 × 720 | Try it |
| Vertical video (Reels, TikTok, Shorts) | 9:16 | 1,080 × 1,920 | Try it |
| Instagram square post | 1:1 | 1,080 × 1,080 | Try it |
| Instagram portrait post | 4:5 | 1,080 × 1,350 | Try it |
| Pinterest pin | 2:3 | 1,000 × 1,500 | Try it |
| Link preview image (Open Graph) | 1.91:1 (40:21) | 1,200 × 630 | Try it |
| Camera photo (most DSLRs and mirrorless) | 3:2 | 3,000 × 2,000 | Try it |
| Classic screen, slides | 4:3 | 1,600 × 1,200 | Try it |
| Ultrawide monitor (sold as 21:9) | 64:27 ≈ 21:9 | 2,560 × 1,080 | Try it |
Platforms change their recommended sizes from time to time — check the platform’s own help page before a large campaign.
Frequently asked questions
How do I calculate an aspect ratio?
Divide the width and the height by their greatest common divisor. 1920 and 1080 are both divisible by 120, which leaves 16 and 9 — so 1920×1080 is 16:9. The calculator above does this for you.
Is 1920×1080 the same as 16:9?
16:9 is the shape; 1920×1080 is one size with that shape. 1280×720, 2560×1440 and 3840×2160 are also 16:9 — they just have fewer or more pixels.
Why is my 1366×768 screen not exactly 16:9?
1366 ÷ 768 = 1.7786, while 16 ÷ 9 = 1.7778. The exact ratio simplifies to 683:384, but it is within 0.05% of 16:9, so it is sold as 16:9. The calculator shows both the exact ratio and the closest standard one.
What aspect ratio should I use for Instagram?
1:1 for a square post, 4:5 for a portrait post (it takes up more of the feed), and 9:16 for Stories and Reels.
Does changing the aspect ratio crop my image?
Changing the shape of an existing image means cropping it, adding empty space, or stretching it — this calculator only does the math. In Nystrel, “Extend the frame” takes the fourth route: it keeps every original pixel and paints in the new edges, so nothing is cropped or stretched.