Aspect Ratio Calculator for AI Renders

Frequently Asked Questions

About aspect ratios, print formats and render resolution

Why doesn't ChatGPT respect the aspect ratio I ask for?

Because in ChatGPT the aspect ratio is a request, not a setting. Image models generate at a small set of fixed sizes — typically square, landscape and portrait — and the prompt only nudges the model toward one of them. Asking for 16:9 or 4:5 in words does not change the canvas the model draws on, so you get the nearest fixed size instead. There are two real fixes: pick a target that matches one of the sizes the model does output, or generate large and crop to the exact ratio afterwards. Tools with an explicit ratio control, RenderAI included, avoid the problem because the ratio is a parameter rather than a sentence.

What aspect ratio should I use for an architecture competition board?

Match the render to the sheet, not the other way round. On a US ARCH sheet you are in luck: ARCH B and ARCH D are exactly 2:3, and ARCH A, C and E are exactly 3:4, so a native render fills the sheet with no crop. On an ISO A sheet — A1 and A0 are the usual competition sizes — every format is 1:√2, which no AI model outputs, so render at 3:2 and crop about 5.7% off the long side. If the render is one plate inside a composed board rather than the whole sheet, 16:9 for the main perspective and 1:1 for detail studies is the combination that lays out most cleanly.

Can AI renders be printed at A1 or A0 size?

Not at full print quality in a single pass. A 4K render has a 4096 px long side, which spreads to 124 DPI across an A1 sheet and 88 DPI across an A0. That is acceptable for a board read from a metre away, where 150 DPI is the practical floor, but it is well below the 300 DPI a handheld document needs. A 4K render does cover A3 at 248 DPI and A4 at 350 DPI. For A1 and A0 at print quality, run an upscale pass first: a 2× upscale takes A1 to 248 DPI and a 4× takes A0 to 350 DPI.

Why doesn't my AI model support the A4/A3 paper ratio?

Every ISO A format has the same 1:√2 (1.414:1) proportion, which is what allows an A3 sheet to fold into two A4s. Image models are trained and configured around screen and camera ratios — 16:9, 4:3, 3:2, 1:1 and their portrait forms — and 1:√2 sits between 3:2 (1.5) and 4:3 (1.333), matching neither. It is not a limitation of one model; no mainstream image model outputs it. Render at 3:2 and crop 5.7% off the long side, or at 4:3 and crop 5.7% off the short side. Both lose the same amount of image.

What DPI do I need for an architectural presentation board?

150 DPI for a board read from a distance of about a metre — pinned-up competition sheets, exhibition panels, site hoardings. 300 DPI for anything held in the hand and read close up: brochures, tender documents, portfolio prints. 96 DPI is enough for a screen or projector. In pixels: an A1 sheet needs 3508 × 4967 px at 150 DPI and 7016 × 9933 px at 300 DPI. Printing a board at 300 DPI when 150 is the requirement doubles the file size along each side for detail nobody will see at that viewing distance.

What is the best aspect ratio for Instagram architecture posts?

4:5 portrait, because it occupies the most vertical space in the feed at 1080 × 1350 px. No AI model outputs 4:5 directly, so render at 3:4 and crop 6.25% off the long side. For Reels and Stories use 9:16, which is native. For a carousel where every slide must align, 1:1 is the safest choice and is also native. Avoid posting a 16:9 render straight to the feed: it renders small on a phone and gets scrolled past.