GPT Image 2.5 Sunburst: AI Image Generator Online

Everything here comes from VdoBloom's GPT Image 2.5 service and credit table for the gpt-image-2-5-sunburst-text-to-image model. The service notes were checked against the live provider API on 12 September 2026, which is why the ratio list differs from the provider's own documentation.

The credit keys are gpt-image-2-5-sunburst-text-to-image-1k, -2k and -4k, at 3, 5 and 8 credits. A code comment in VdoBloom's credit table records that this price was checked against the provider's rate on 12 September 2026 and is identical for Flare and Sunburst, for text-to-image and image-to-image. Dollar figures use the Lite rate of $0.05 a credit. The cost is shown before you generate, and a failed job is refunded.

The honest answer is: free for a few images, then paid. VdoBloom gives every new account 10 free credits. On Sunburst that is three 1K images (9 credits), two 2K images (10 credits) or one 4K image (8 credits). There is no daily free allowance after that, and VdoBloom does not run a free Sunburst tier. When you need more, a one-time 300-credit pack is $19.50 and does not expire, or the Lite plan is $15 a month for 300 credits that reset each billing cycle.

To get the most from the free credits, leave the ratio on auto and the resolution on 1K while you work out the prompt, then spend the rest on one 2K or 4K version of the prompt you keep.

These sit next to each other in the Image Generator. Sunburst and Flare are the same release with the same inputs and the same price; VdoBloom's service describes the difference as latency against precision, and VdoBloom does not publish a quality ranking between them. Since a test costs the same on either, the practical way to choose is to run your prompt on both at 1K. GPT Image 2 is the older release at the same price with stricter resolution rules. Nano Banana 2.1 is cheaper at 2K and 4K.

GPT Image 2's two traps (auto forcing 1K, and 1:1 refusing 4K) are not carried over to 2.5. Sunburst renders 1:1 at 4K. The one rule it does have: 27:16, 16:27, 9:8 and 8:9 are 1K-only at the provider. VdoBloom's service lowers the resolution to 1K for those ratios instead of failing the job, so pick one of the nine standard ratios if you need 2K or 4K.

Sunburst is listed under its own name in the model pickers; the 3/5/8 credit ladder is the same everywhere.

Treat the 20,000-character cap as room for a precise brief. Lead with the subject and its action, then the layout (what is where, how many, what size), the lighting and the palette. For on-image text, quote the exact words and say where they sit. Because Flare and Sunburst take identical inputs, you can paste the same prompt into both and keep the better result at no extra cost.

Draft at 1K for 3 credits until the composition is right, then re-run once at 2K or 4K. If a result looks soft, check that the ratio was not one of the four 1K-only ratios before blaming the prompt.

Sunburst carries VdoBloom's STRICT label, so OpenAI's filter declines more prompts involving real people, violence or sexual content than HOT-labelled models do. Four ratios are held to 1K. The 5:4 and 4:5 ratios available on GPT Image 2 are not accepted for 2.5. The provider also documents a transparent-background option for 2.5, but VdoBloom's interface does not offer it for this model today. This page takes no reference images (use the I2I model for edits). And it is a proprietary hosted model, so if the provider fails a job, the credits come back automatically.

VdoBloom does not rank Sunburst against Flare on quality. Both cost the same, so a 3-credit test of each on your own prompt is the fastest way to decide.