Aspect Ratio Calculator

Frequently asked questions

What is an aspect ratio?

An aspect ratio is the proportional relationship between the width and height of a rectangle, expressed as width:height (e.g. 16:9). It describes the shape of the frame without specifying the actual dimensions. The same ratio can apply to a thumbnail or a cinema screen.

What aspect ratio is 1920×1080?

1920×1080 is 16:9 — the standard widescreen format used for HD and Full HD video, most monitor screens, and YouTube. It is the most common video and display aspect ratio in use today.

What are the most common aspect ratios?

16:9 is standard widescreen (HD video, most monitors). 4:3 is the old TV and VGA standard. 1:1 is square (Instagram posts). 9:16 is vertical video (Stories, TikTok, Shorts). 21:9 is ultrawide cinema. 3:2 is used by most DSLR cameras.

How do I maintain aspect ratio when resizing?

Enter your original width and height, choose the ratio lock mode, then enter a new value for just one dimension. aspectDash calculates the other automatically so the proportions stay identical. This prevents stretching or squashing.

What is the aspect ratio for Instagram?

Instagram supports several ratios: 1:1 (square feed post), 4:5 (portrait feed post, maximum vertical space), 1.91:1 (landscape feed post), and 9:16 (Stories and Reels). The 4:5 portrait ratio gives your image the most screen space in the feed.

What does "letterboxing" mean?

Letterboxing is the black bars that appear above and below video when content filmed in a wider ratio (like 21:9) is displayed on a narrower screen (like 16:9). The opposite — black bars on the sides — is called pillarboxing.

What is a 4:5 ratio in pixels?

There is no single answer — any dimensions with the same ratio work. Common 4:5 values include 1080×1350 (Instagram portrait), 800×1000, and 400×500. Enter either dimension into aspectDash and it will calculate the other.

How is aspect ratio calculated?

Divide both width and height by their greatest common divisor (GCD) to get the simplified ratio. For example, 1920 and 1080 share a GCD of 120, so 1920÷120=16 and 1080÷120=9, giving 16:9. aspectDash does this automatically.