Google: Gemini 3 Flash Preview vs OpenAI: o3 Pro
Head-to-head API pricing and cost comparison between Google’s Google: Gemini 3 Flash Preview and OpenAI’s OpenAI: o3 Pro. Prices auto-refresh daily from OpenRouter.
Google: Gemini 3 Flash Preview is 98% cheaper for input tokens; Google: Gemini 3 Flash Preview also wins on output tokens.
Side-by-side comparison
| Spec | Google: Gemini 3 Flash Preview | OpenAI: o3 Pro |
|---|---|---|
| Input price (per 1M) | $0.50 | $20.00 |
| Cached input (per 1M) | $0.05 | — |
| Output price (per 1M) | $3.00 | $80.00 |
| Batch input (per 1M) | — | $10.00 |
| Batch output (per 1M) | — | $40.00 |
| Reasoning price (per 1M) | $3.00 | — |
| Context window | 1049K | 200K |
| Vision support | Yes | Yes |
| Caching support | Yes | No |
| Batch API | No | Yes |
| Reasoning capability | Yes | Yes |
Monthly cost at volume
Estimated monthly API spend at common production traffic levels (input/output tokens per request shown).
| Volume | Google: Gemini 3 Flash Preview | OpenAI: o3 Pro | Savings |
|---|---|---|---|
1K req/day 500in / 200out tokens | $25.50 | $780.00 | $754.50 Google: Gemini 3 Flash Preview wins |
10K req/day 1500in / 500out tokens | $675.00 | $21,000 | $20,325 Google: Gemini 3 Flash Preview wins |
100K req/day 3000in / 800out tokens | $11,700 | $372,000 | $360,300 Google: Gemini 3 Flash Preview wins |
1M req/day 8000in / 2000out tokens | $300,000 | $9,600,000 | $9,300,000 Google: Gemini 3 Flash Preview wins |
Adjust input/output token counts, request volume, batch & cached pricing.
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Frequently asked questions
Which is cheaper, Google: Gemini 3 Flash Preview or OpenAI: o3 Pro?
For input tokens, Google: Gemini 3 Flash Preview is roughly 98% cheaper at $0.50/1M vs $20.00/1M. For output tokens, Google: Gemini 3 Flash Preview wins at $3.00/1M. Real-world cost depends on your input/output ratio — use the calculator to model your actual workload.
What’s the context window difference?
Google: Gemini 3 Flash Preview has a context window of 1049K tokens. OpenAI: o3 Pro offers 200K 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: Gemini 3 Flash Preview or OpenAI: o3 Pro?
Choose Google: Gemini 3 Flash Preview if you’re already on the Google stack, want reasoning capabilities, or prefer its lower input price. Choose OpenAI: o3 Pro for OpenAI’s ecosystem, native vision input, or its differentiated capabilities. 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: May 28, 2026.