AI wallpaper generator: 4K desktop and phone wallpapers

An AI wallpaper generator turns a text prompt or a photo into an image shaped like your screen; generate it at your screen's pixel size so it fills the display without scaling. On Sume, ChatGPT Image 2.5 takes a custom pixel size, so ask for exactly 3840 × 2160 for a 4K desktop, and for a phone ask for the screen size rounded up to multiples of 16, then crop the few extra pixels.

Sume facts come from the Image API docs and the request schema in the Sume API reference; phone resolutions come from Apple's tech specs pages for the iPhone 17 and iPhone Air. All were read on 2026-09-27. Which models have a 4K tier at all is covered in 4K AI image generation.

What size should an AI wallpaper be?

Your screen's resolution: check your display settings or the device's tech specs. Apple lists the iPhone 17 display at 2622 by 1206 pixels and the iPhone Air at 2736 by 1260, so held upright they are 1206 and 1260 pixels wide.

A ChatGPT Image 2.5 custom size needs both edges in multiples of 16, a longest edge of at most 3840, a shape no wider than 3:1, and 655,360 to 8,294,400 pixels. Screens that miss the first rule need a small crop:

How do I generate a 4K wallpaper?

Send the size as image_size to openai/gpt-image-2.5 on POST /v1/images. 3840 × 2160 sits exactly on both ceilings: the 3840-pixel edge and 8,294,400 pixels. Describe the scene, ask for no text, and keep the subject clear of where your icons sit.

• The call waits up to 30 seconds. High quality, the default on this model, is one of the slow configurations most likely to return 202 with a job instead; then poll GET /v1/jobs/{id}/status and fetch GET /v1/jobs/{id}/result.
• Nano Banana 2 and Nano Banana Pro offer a 4K tier instead: send resolution: "4K" with aspect_ratio: "16:9". The docs don't give that tier's pixel size, so check the file against your screen.
• Results are Sume-hosted, signed URLs in data[].url, so download the wallpaper you keep.

curl -X POST "https://api.sume.com/v1/images" \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-image-2.5",
    "prompt": "Desktop wallpaper: a misty pine forest at dawn, soft light, calm and uncluttered, no text",
    "image_size": { "width": 3840, "height": 2160 },
    "output_format": "png"
  }'

How do I make a phone wallpaper?

Round each edge up to the next multiple of 16 and crop the difference in any photo editor. For the iPhone 17, ask for 1216 × 2624, then crop 10 px of width and 2 px of height. Keep the subject near the middle so the crop never touches it.

Grok Imagine and Nano Banana take a ratio instead of pixels. Grok Imagine (x-ai/grok-image) lists the tall phone shapes 9:19.5 and 9:20 and returns one image per call today; Nano Banana lists 9:16. Check the size of what comes back and resize it to your screen.

Can I turn my own photo into a wallpaper?

Yes. Send the photo to ChatGPT Image 2.5 in input_references as a public HTTPS URL, say what to change, such as turning it into a watercolor, and send the wallpaper's image_size so the result takes your screen's shape rather than the photo's. The model takes up to 16 reference images. The result is a new image, so details of the photo can change.

If the photo is already right and you only need more pixels, send its public HTTPS URL to Image Upscale 1.0 with an upscale_factor from 1 to 4 instead; AI image upscaler API covers that call.

What does an AI wallpaper cost, and what are the limits?

• Each model's per-image rate is in the pricing line of GET /v1/images/models/{model_id}/endpoints, plus a 5.5% agent fee by default. ChatGPT Image 2.5 estimates each request from the image's size and quality, and usage.cost in the response is the USD amount billed; a failed generation is not billed.
• n returns up to 4 versions per call on ChatGPT Image 2.5 today, so you can pick your favorite; Grok Imagine returns one.
• On Nano Banana and Grok Imagine, a pixel size you send is mapped to the nearest listed ratio, and in current code Sume does not resize the file to it.
• The Image API makes still images (PNG, JPEG, or WebP), not animated wallpapers.