Google: Nano Banana Pro (Gemini 3 Pro Image) vs OpenAI: GPT-5.6 Luna Pro
Head-to-head API pricing and cost comparison between Google’s Google: Nano Banana Pro (Gemini 3 Pro Image) and OpenAI’s OpenAI: GPT-5.6 Luna Pro. Prices auto-refresh daily from OpenRouter.
OpenAI: GPT-5.6 Luna Pro is 95% cheaper for input tokens; OpenAI: GPT-5.6 Luna Pro also wins on output tokens.
Side-by-side comparison
| Spec | Google: Nano Banana Pro (Gemini 3 Pro Image) | OpenAI: GPT-5.6 Luna Pro |
|---|---|---|
| Input price (per 1M) | $2.00 | $0.10 |
| Cached input (per 1M) | $0.20 | $0.01 |
| Output price (per 1M) | $12.00 | $0.60 |
| Batch input (per 1M) | — | $0.05 |
| Batch output (per 1M) | — | $0.30 |
| Reasoning price (per 1M) | $12.00 | — |
| Context window | 131K | 1050K |
| Vision support | Yes | Yes |
| Caching support | Yes | Yes |
| Batch API | No | Yes |
| Reasoning capability | Yes | No |
Monthly cost at volume
Estimated monthly API spend at common production traffic levels (input/output tokens per request shown).
| Volume | Google: Nano Banana Pro (Gemini 3 Pro Image) | OpenAI: GPT-5.6 Luna Pro | Savings |
|---|---|---|---|
1K req/day 500in / 200out tokens | $102.00 | $5.10 | $96.90 OpenAI: GPT-5.6 Luna Pro wins |
10K req/day 1500in / 500out tokens | $2,700 | $135.00 | $2,565 OpenAI: GPT-5.6 Luna Pro wins |
100K req/day 3000in / 800out tokens | $46,800 | $2,340 | $44,460 OpenAI: GPT-5.6 Luna Pro wins |
1M req/day 8000in / 2000out tokens | $1,200,000 | $60,000 | $1,140,000 OpenAI: GPT-5.6 Luna Pro wins |
Adjust input/output token counts, request volume, batch & cached pricing.
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Frequently asked questions
Which is cheaper, Google: Nano Banana Pro (Gemini 3 Pro Image) or OpenAI: GPT-5.6 Luna Pro?
For input tokens, OpenAI: GPT-5.6 Luna Pro is roughly 95% cheaper at $0.10/1M vs $2.00/1M. For output tokens, OpenAI: GPT-5.6 Luna Pro wins at $0.60/1M. Real-world cost depends on your input/output ratio — use the calculator to model your actual workload.
What’s the context window difference?
Google: Nano Banana Pro (Gemini 3 Pro Image) has a context window of 131K tokens. OpenAI: GPT-5.6 Luna Pro offers 1050K tokens. Larger context windows are valuable for long documents, RAG pipelines, and multi-turn conversations — but they come with higher input-token bills if you fill them every request.
Should I use Google: Nano Banana Pro (Gemini 3 Pro Image) or OpenAI: GPT-5.6 Luna Pro?
Choose Google: Nano Banana Pro (Gemini 3 Pro Image) if you’re already on the Google stack, want reasoning capabilities, or prefer its feature set. Choose OpenAI: GPT-5.6 Luna Pro for OpenAI’s ecosystem, native vision input, or its cheaper input tokens. Run a small benchmark on your own prompts before committing — price is only one axis.
How are these prices kept current?
Prices are pulled directly from OpenRouter’s public models API once every 24 hours via a Convex cron job, then normalized to per-1M-token figures. Last refresh: Jul 31, 2026.