GPT-6 Astra vs Gemini 3.8 Flash
Gemini 3.8 Flash comes out ahead, 75 to 68 on our weighted score, and it is the cheaper option too.
OpenAIGPT-6 Astra
68/100- ECI166.5
- Price$10.00 / $50.00
- Context1.05M
- Our pick
GoogleGemini 3.8 Flash
75/100- ECI156.9
- Price$0.75 / $3.75
- Context1.05M
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Gemini 3.8 Flash is our pick
Gemini 3.8 Flash is the better all-round choice, scoring 75/100 against GPT-6 Astra (68). It leads on price and inputs & features. GPT-6 Astra wins on capability. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
- CapabilityGPT-6 AstraCapabilities Index (ECI): GPT-6 Astra 166.5 · Gemini 3.8 Flash 156.9
- Lowest priceGemini 3.8 FlashGemini 3.8 Flash $1.50 · GPT-6 Astra $20.00 per 1M tokens (3:1 blend)
- Longest contextAbout the sameGPT-6 Astra 1,050,000 · Gemini 3.8 Flash 1,048,576 tokens
- Widest inputsGemini 3.8 FlashGPT-6 Astra: Text, Images, PDFs · Gemini 3.8 Flash: Text, Images, PDFs, Audio, Video
- Self-hostingNo open weightsBoth are available only through APIs
| Measure | Weight | GPT-6 Astra | Gemini 3.8 Flash |
|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 99 | 87 |
| Price | 25% | 0 | 42 |
| Inputs & features | 15% | 80 | 100 |
| Context window | 10% | 61 | 61 |
| Overall | 100% | 68/100 | 75/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | GPT-6 AstraOpenAI | Gemini 3.8 FlashGoogle |
|---|---|---|
| Capability | ||
| Capabilities Index (ECI) | 166.5 (best) | 156.9 |
| ECI rank | #2 of 148 (best) | #15 of 148 |
| GPQA DiamondGraduate-level science questions | 95.8% (best) | 95.4% |
| FrontierMath Tiers 1–3Research-level mathematics | 93.7% (best) | 68.4% |
| OTIS Mock AIME 2024–2025Competition mathematics | 100% (best) | 98.9% |
| SimpleQA VerifiedShort factual questions | 75.6% (best) | 69.7% |
| Price per million tokens | ||
| Input | $10.00 | $0.75 (best) |
| Output | $50.00 | $3.75 (best) |
| Cached input | $1.00 | $0.075 (best) |
| Blended (3:1) | $20.00 | $1.50 (best) |
| Long-context rate | Over 272K: $20.00 / $75.00 | Same rate |
| Price source | Official OpenAI API | Official Google API |
| Limits | ||
| Context window | 1,050,000 tokens (best) | 1,048,576 tokens |
| Max output | 128,000 tokens (best) | 65,536 tokens |
| Inputs and features | ||
| Text | Yes | Yes |
| Images | Yes | Yes |
| PDFs | Yes | Yes |
| Audio | No | Yes |
| Video | No | Yes |
| Reasoning | Yeslow · medium · high · xhigh · max | Yeslow · medium · high |
| Tool calling | Yes | Yes |
| Structured output | Yes | Yes |
| Availability | ||
| Weights | Proprietary | Proprietary |
| API model ID | gpt-6-astra | gemini-3.8-flash |
| API providers | 26 (best) | 21 |
| Released | Sep 4, 2026 | Sep 2, 2026 |
| Knowledge cutoff | Apr 30, 2026 | — |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- GPT-6 Astra$200.00
- Gemini 3.8 Flash$15.00
Which should you choose?
Which is better: GPT-6 Astra or Gemini 3.8 Flash?
Gemini 3.8 Flash is the better all-round choice, scoring 75/100 against GPT-6 Astra (68). It leads on price and inputs & features. GPT-6 Astra wins on capability. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, GPT-6 Astra or Gemini 3.8 Flash?
Gemini 3.8 Flash is cheaper at $0.75 input / $3.75 output per million tokens (official Google API price). GPT-6 Astra costs $10.00 input / $50.00 output per million tokens (official OpenAI API price). At a typical mix of three input tokens to one output token, that is $1.50 per million tokens for Gemini 3.8 Flash versus $20.00 for GPT-6 Astra (13× as much).
Which scores higher on benchmarks?
GPT-6 Astra scores higher on the Capabilities Index (ECI): GPT-6 Astra 166.5 (#2 of 148) and Gemini 3.8 Flash 156.9 (#15 of 148). Their confidence ranges do not overlap (163.1–171.1 vs 154.6–160.4), so the gap is a real one. On individual benchmarks: GPQA Diamond — GPT-6 Astra 95.8%, Gemini 3.8 Flash 95.4%; FrontierMath Tiers 1–3 — GPT-6 Astra 93.7%, Gemini 3.8 Flash 68.4%; OTIS Mock AIME 2024–2025 — GPT-6 Astra 100%, Gemini 3.8 Flash 98.9%; SimpleQA Verified — GPT-6 Astra 75.6%, Gemini 3.8 Flash 69.7%.
Which is better for coding?
There are no published SWE-bench Verified results for GPT-6 Astra and Gemini 3.8 Flash yet, so there is no like-for-like coding score. On overall capability, GPT-6 Astra leads, which tends to carry over to coding, but test on your own codebase. Both support tool calling for agent workflows.
Which has the bigger context window?
Their context windows are effectively the same size: GPT-6 Astra 1,050,000 and Gemini 3.8 Flash 1,048,576 tokens. Maximum output per response: GPT-6 Astra up to 128,000, Gemini 3.8 Flash up to 65,536 tokens.
Which can read images, PDFs, audio or video?
GPT-6 Astra accepts text, images and PDFs; Gemini 3.8 Flash accepts text, images, PDFs, audio and video. Gemini 3.8 Flash handles the widest range of inputs.
Are any of these open source?
No. GPT-6 Astra and Gemini 3.8 Flash are proprietary and only available through APIs and apps.
Which is newer?
GPT-6 Astra is the newest, released Sep 4, 2026. Gemini 3.8 Flash came out Sep 2, 2026. Knowledge cutoff: GPT-6 Astra Apr 30, 2026.
How do you decide the winner?
Each model gets a 0–100 score on capability (50%, independent benchmark results); price (25%, blended price per million tokens (3 input : 1 output), log scale); inputs & features (15%, image, PDF, audio and video input, tool calling, structured output and reasoning); context window (10%, maximum tokens per request, log scale). Dimensions missing for any model are dropped and the remaining weights rescaled, so every model is judged on the same evidence. Specs and prices come from public model listings and the labs’ own API pages; capability scores come from independent benchmark runs. Data updated Oct 4, 2026.
