Sizes and aspect ratios
Why the same shape has two different names, and how to be sure you get the one you asked for.
2 min read · last checked
The same shape, two spellings
Some models take a ratio as text: 16:9, 9:16, 1:1. Others take a named size: square_hd, landscape_16_9, portrait_4_3. They mean the same thing, and no model takes both.
The names catch people out in one specific way, and it is worth reading twice: portrait_16_9 is a tall image in the proportion 16:9. As a number it is 9 divided by 16, not 16 divided by 9.
- square_hd , 1.000 wide over tall
- square , 1.000 wide over tall
- portrait_4_3 , 0.750 wide over tall
- portrait_16_9 , 0.563 wide over tall
- landscape_4_3 , 1.333 wide over tall
- landscape_16_9 , 1.778 wide over tall
How the studio handles it
You pick a shape, not a field name. The studio looks up what the chosen model actually offers and picks the closest option it really has.
If nothing on that model comes within 3 percent of the shape you asked for, it refuses and says so. It does not quietly round to the nearest one. Rounding is how you end up paying for a landscape picture when you asked for a portrait, with nothing on screen to tell you.
What comes out is measured, not assumed
On 22 August 2026 we ran eight real generations across four models and read the pixel dimensions out of the returned files rather than trusting the setting.
The named sizes land exactly: 1024x576, 576x1024, 768x1024. The ratio-as-text models round their output to multiples of 64 pixels, so a request for 16:9 comes back as 1344x768, which is 1.750 against the 1.778 you asked for. That is 1.6 percent off, and it is why the tolerance is three percent and not one.
Picking a shape for where it will be seen
Vertical 9:16 fills a phone screen. 4:5 is the taller feed format that does not go full height. 1:1 is safe almost anywhere. 16:9 is the standard for players and presentations. Very wide cinema framing at 2.39:1 exists but few models offer it, and the studio will tell you which.