Aspect ratio

Aspect ratio describes shape, not size. A 16:9 image can be 1920 by 1080 pixels or 3840 by 2160 and still have the same proportion; resolution is the separate question of how many pixels it has. In architectural images the ratio shapes the composition: a wide frame suits a long street facade or a landscape, a tall frame suits a tower or a double-height interior, and a square crops to the essentials.

In practice

• 16:9 fits presentation slides and screens. 4:5 and 1:1 are common for social media feeds; 9:16 for stories and vertical video.
• ISO paper sizes (A4, A3, A1) share a ratio of about 1:1.41, so an image composed for A3 scales to A1 without cropping.
• Decide the ratio before composing. Cropping a 16:9 render to 4:5 later can cut off the entrance or the top of the building.
• Keep a set consistent. A board of images with mixed ratios looks less resolved than one with a shared format.
• An aspect ratio planner works out pixel dimensions for a target ratio, and a print size checker confirms whether an image is large enough for a paper size.

In Rendair

If a render needs a wider or taller frame than it was made at, Extend Image adds to the edges instead of cropping, keeping the building intact while the format changes.