Free Aspect Ratio Calculator

About the Aspect Ratio Calculator

Free aspect ratio calculator with social video presets. Lock a ratio, resize either dimension, or jump to the exact pixel sizes TikTok, Reels, Shorts and Meta want.

Every calculation and generation runs entirely in your browser - free, instant, nothing uploaded. Getting the ratio right is step one; filling it with creative that holds attention is step two. Creetr generates ready-to-post 9:16 UGC ads from a product link. Start with Creetr - no camera, no creator fees.

Aspect ratio is the proportional relationship between a video or image's width and height, written as width:height — 9:16 for vertical, 16:9 for widescreen. Lock a ratio above, change either dimension, and the other updates to match. The presets jump straight to the ratios each social platform actually wants.

How to Calculate Aspect Ratio

To find the ratio from known dimensions, divide both by their greatest common divisor. 1920 × 1080 both divide by 120, giving 16:9. 1080 × 1920 gives 9:16.

To find a missing dimension from a known ratio:

• height = width × (ratio height ÷ ratio width)
• width = height × (ratio width ÷ ratio height)

A 1080-wide video at 9:16 is 1080 × (16 ÷ 9) = 1920 tall. That is the calculation the tool above runs.

Aspect Ratio by Platform

The one that costs advertisers money: 4:5, not 1:1, is the right default for Meta feed. It occupies about 25% more vertical screen on a phone than a square for the same placement, and Meta permits it in feed. Uploading squares to feed is the single most common free reach left on the table.

Aspect Ratio Is Not Resolution

These get used interchangeably and they are not the same thing.

• Aspect ratio is the shape — 9:16.
• Resolution is the pixel count — 1080 × 1920.

Both 720 × 1280 and 1080 × 1920 are 9:16. They fill the screen identically; one is sharper. Platforms enforce the ratio strictly and treat resolution as a quality floor, so getting the shape right matters more than chasing 4K on a phone-first placement.

What Happens When the Ratio Is Wrong

The platform does one of three things, none of them good:

Letterboxing. Black bars fill the mismatch. A 16:9 video in a 9:16 slot becomes a small strip in the middle of a mostly black screen — the clearest possible signal that the creative was repurposed, and it reliably underperforms.

Auto-cropping. The platform crops to fit and picks the crop itself. Text at the edges, faces near the frame border and product labels get cut.

Rejection. Some ad placements refuse out-of-spec assets outright rather than adapting them.

Shooting Once for Multiple Ratios

You do not need a separate shoot per platform. Frame for the tightest crop and let the wider ones have the extra room:

1. Shoot 9:16 — the tallest common ratio.
2. Keep the subject, all text and the product inside the centre 4:5 area. That region survives every crop down to 1:1.
3. Keep the top and bottom ~15% clear of anything essential — that is where platform UI, captions and CTA buttons sit.
4. Export 9:16 as the master, then crop to 4:5 and 1:1 from it without reshooting.

This is what people mean by shooting for safe zones, and it converts one shoot into three deliverables. Full per-placement numbers are in the social video specs.

Common Resolutions at a Glance

For short-form social, 1080 × 1920 is the practical sweet spot — it meets every platform's quality bar, and uploading larger mostly buys you a longer processing wait before the platform re-encodes it down anyway.

Frequently asked questions

How do I calculate aspect ratio?+

To get the ratio from known dimensions, divide both by their greatest common divisor — 1920 × 1080 both divide by 120, giving 16:9. To find a missing dimension from a known ratio, height = width × (ratio height ÷ ratio width). A 1080-wide video at 9:16 is 1080 × (16 ÷ 9) = 1920 tall.

What aspect ratio is a TikTok video?+

9:16 vertical, normally at 1080 × 1920. The same ratio covers Instagram Reels, YouTube Shorts and Stories, which is why 9:16 is the sensible master format for short-form — you can crop down to 4:5 and 1:1 from it without reshooting, but you cannot crop up.

Is 4:5 or 1:1 better for Meta feed?+

4:5, and it is free reach most advertisers leave on the table. At 1080 × 1350, a 4:5 asset occupies roughly 25% more vertical screen on a phone than a 1080 × 1080 square in the same placement, and Meta permits it in feed. Squares are a legacy default, not an optimal one.

What is the difference between aspect ratio and resolution?+

Aspect ratio is the shape; resolution is the pixel count. Both 720 × 1280 and 1080 × 1920 are 9:16 and fill the screen identically — one is just sharper. Platforms enforce the ratio strictly and treat resolution as a quality floor, so getting the shape right matters more than chasing 4K on a phone-first placement.

What happens if my video is the wrong aspect ratio?+

One of three things, none good. The platform letterboxes it, leaving black bars that visibly mark the creative as repurposed and reliably underperform. Or it auto-crops and picks the crop itself, cutting edge text, faces near the border and product labels. Or the ad placement rejects the asset outright.

Can I shoot once for TikTok, Reels and Meta feed?+

Yes. Shoot 9:16, the tallest common ratio, and keep the subject, all text and the product inside the centre 4:5 area — that region survives every crop down to 1:1. Keep the top and bottom 15% clear of anything essential, since platform UI, captions and CTA buttons sit there. Export 9:16 as the master, then crop to 4:5 and 1:1 from it.

What resolution should I use for short-form video?+

1080 × 1920 for 9:16 is the practical sweet spot. It clears every platform's quality bar, and uploading larger mostly buys a longer processing wait before the platform re-encodes it down anyway. The 4:5 and 1:1 equivalents are 1080 × 1350 and 1080 × 1080.