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GPT-6 Astra vs Gemini 3.1 Pro (Preview)
A straight cost comparison of GPT-6 Astra (OpenAI) and Gemini 3.1 Pro (Preview) (Google Gemini), per 1,000,000 tokens, verified October 2026.
Rate-by-rate comparison
| Metric | GPT-6 Astra | Gemini 3.1 Pro (Preview) | Winner |
|---|---|---|---|
| Input / 1M | $10 | $2 | Gemini 3.1 Pro (Preview) |
| Cached input / 1M | $1 | $0.20 | Gemini 3.1 Pro (Preview) |
| Cache write / 1M | $12.50 | — | Gemini 3.1 Pro (Preview) |
| Output / 1M | $50 | $12 | Gemini 3.1 Pro (Preview) |
| Context window | 1,050,000 | 1,000,000 | GPT-6 Astra |
| Batch API | Yes | Yes | Tie |
| Long-context tier | > 272,000 | > 200,000 | — |
For per-token metrics, the lower number wins. For context window and batch support, the higher or broader option wins. A dash means the provider does not publish that rate: a missing cache-write fee means writes are not billed per token, while a missing cached-input rate means cache hits bill at the full input rate.
Blended cost: 1M input + 250K output
| Model | Blended cost | Difference |
|---|---|---|
| GPT-6 Astra | $22.50 | +$17.50 |
| Gemini 3.1 Pro (Preview) | $5 | Cheaper |
Three workloads, two bills
| Workload | GPT-6 Astra | Gemini 3.1 Pro (Preview) | Winner |
|---|---|---|---|
| Support chat 1,000 requests · 4K input / 600 output | $70 | $15.20 | Gemini 3.1 Pro (Preview) |
| RAG with caching 1,000 requests · 50K input (45K cached) / 1K output | $146 | $31.08 | Gemini 3.1 Pro (Preview) |
| Nightly batch job 10,000 requests · 10K input / 2K output | $1000 | $220 | Gemini 3.1 Pro (Preview) |
Which one should you pick?
GPT-6 Astra wins on none of the three workloads above, while Gemini 3.1 Pro (Preview) wins on support chat, cached RAG, nightly batch job.
Beyond price, the two differ on input rate ($10 vs $2); output rate ($50 vs $12); cached-input rate ($1 vs $0.20); cache-write rate ($12.50 vs —); context window (1,050,000 vs 1,000,000).
Batch mode is available on GPT-6 Astra and Gemini 3.1 Pro (Preview), which halves the nightly job. Both publish cached-input discounts, so a stable system prompt is worth caching on either.
FAQ
Is GPT-6 Astra cheaper than Gemini 3.1 Pro (Preview)?
On a blended 1M-input-plus-250K-output workload, Gemini 3.1 Pro (Preview) is cheaper by 78% ($5 vs $22.50). The gap changes for cache-heavy prompts and for batch jobs, as the workload table shows.
Which handles longer prompts, GPT-6 Astra or Gemini 3.1 Pro (Preview)?
GPT-6 Astra has the larger context window (1,050,000 vs 1,000,000 tokens). Watch the long-context threshold on GPT-6 Astra and Gemini 3.1 Pro (Preview): rates rise once input passes it.
Do both models support prompt caching?
GPT-6 Astra bills cached reads at $1 per 1M; Gemini 3.1 Pro (Preview) at $0.20.