AI Image Resolution Guide: 1K vs 2K vs 4K Explained (2026)
Confused about AI image resolutions? Learn what 1K, 2K, and 4K actually mean, how many pixels each delivers, which resolution to choose for your project, and how credits work across different models.
AI image generators use 1K, 2K, and 4K to describe output resolution — but what do these actually mean in pixels, and which one should you choose? Here's the definitive guide based on Nano Banana's real model specifications.
What Do 1K, 2K, and 4K Actually Mean?
| Resolution | Approximate Size | Best For |
|---|---|---|
| 1K | ~1024px (longest edge) | Social media, web images, quick drafts |
| 2K | ~2048px (longest edge) | High-quality web, presentations, small print |
| 4K | ~3840px (longest edge) | Large format print, posters, professional output |
These aren't exact pixel dimensions — they're approximately the longest edge of the output image. A 2K image might be 2048×1152 (16:9), 2048×2048 (1:1), or 1152×2048 (9:16), depending on your chosen aspect ratio.
Resolution Pricing by Model
Different models charge different amounts for each resolution tier. Here's the actual pricing on Nano Banana:
| Model | 1K | 2K | 4K |
|---|---|---|---|
| Nano Banana 2 | 10 credits | 10 credits | 15 credits |
| Nano Banana Pro | 10 credits | 10 credits | 20 credits |
| Nano Banana | 5 credits (Auto) | — | — |
| GPT Image 2 | 5 credits | 10 credits | 15 credits |
| Sora Image | 5 credits | 10 credits | 15 credits |
| Flux 2 Pro | 5 credits | 10 credits | — |
| Seedream 4.5 | — | 10 credits | 15 credits |
| Seedream 5.0 | — | 10 credits | 15 credits |
Which Resolution Should You Choose?
Choose 1K if:
- Posting to Instagram, Twitter, or Facebook (these platforms compress images anyway)
- Creating blog illustrations or article headers
- Testing a new prompt — iterate cheap, then upgrade for the final version
- Using models like GPT Image 2 at 1K (only 5 credits, great value)
Choose 2K if:
- Your image will be used as a website hero or full-screen background
- You're printing at sizes up to ~8×10 inches
- You need more detail for close-up viewing (portraits, product shots)
- With Nano Banana 2 or Nano Banana Pro — 2K costs the same as 1K (both 10 credits), so always pick 2K with these models
Choose 4K if:
- Printing posters, large canvas, or anything bigger than 8×10 inches
- You need maximum detail for professional client delivery
- You want to crop into the image later and still have enough resolution
- The extra 5-10 credits are worth it for a final production asset
Aspect Ratios and Resolution
Your chosen aspect ratio affects the actual pixel dimensions:
- 1:1 (Square) — 1K ≈ 1024×1024, 2K ≈ 2048×2048, 4K ≈ 3840×3840
- 16:9 (Widescreen) — 1K ≈ 1024×576, 2K ≈ 2048×1152, 4K ≈ 3840×2160
- 9:16 (Vertical/Story) — 1K ≈ 576×1024, 2K ≈ 1152×2048, 4K ≈ 2160×3840
Pro Strategy: Draft at 1K, Deliver at 4K
Here's the workflow that saves credits without sacrificing quality:
- Iterate at 1K — try different prompts, aspect ratios, and models at the cheapest tier
- Pick your winner — once you have the composition you want
- Re-generate at 2K or 4K — bump up the resolution for the final version
- Optional: run through AI Image Enhancer — for print-ready output above 4K
This way you spend 5-10 credits per iteration instead of 15-20, and only pay for high resolution when you know you want the result.