Gemini 3.8 Flash vs GPT-6 Astra vs Muse Spark 1.3
Too close to call on our weighted score (Gemini 3.8 Flash 75, Muse Spark 1.3 73, GPT-6 Astra 68). The right pick depends on what you value most.
GoogleGemini 3.8 Flash
75/100- ECI156.9
- Price$0.75 / $3.75
- Context1.05M
OpenAIGPT-6 Astra
68/100- ECI166.5
- Price$10.00 / $50.00
- Context1.05M
MetaMuse Spark 1.3
73/100- ECI156.9
- Price$1.25 / $4.25
- Context1.05M
Too close to call
It is close. Our weighted score puts them within 2 points (Gemini 3.8 Flash 75/100, Muse Spark 1.3 73/100, GPT-6 Astra 68/100), so choose by what matters most for your work: GPT-6 Astra for raw capability and Gemini 3.8 Flash on price. 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 · Muse Spark 1.3 156.9
- Lowest priceGemini 3.8 FlashGemini 3.8 Flash $1.50 · Muse Spark 1.3 $2.00 · 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 · Muse Spark 1.3 1,048,576 tokens
- Widest inputsGemini 3.8 Flash and Muse Spark 1.3Gemini 3.8 Flash: Text, Images, PDFs, Audio, Video · GPT-6 Astra: Text, Images, PDFs · Muse Spark 1.3: Text, Images, PDFs, Audio, Video
- Self-hostingNo open weightsAll three are available only through APIs
| Measure | Weight | Gemini 3.8 Flash | GPT-6 Astra | Muse Spark 1.3 |
|---|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 87 | 99 | 87 |
| Price | 25% | 42 | 0 | 36 |
| Inputs & features | 15% | 100 | 80 | 100 |
| Context window | 10% | 61 | 61 | 61 |
| Overall | 100% | 75/100 | 68/100 | 73/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | Gemini 3.8 FlashGoogle | GPT-6 AstraOpenAI | Muse Spark 1.3Meta |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 156.9 | 166.5 (best) | 156.9 |
| ECI rank | #15 of 148 | #2 of 148 (best) | #17 of 148 |
| GPQA DiamondGraduate-level science questions | 95.4% | 95.8% (best) | — |
| FrontierMath Tiers 1–3Research-level mathematics | 68.4% | 93.7% (best) | 74.4% |
| OTIS Mock AIME 2024–2025Competition mathematics | 98.9% | 100% (best) | 99.2% |
| SimpleQA VerifiedShort factual questions | 69.7% | 75.6% (best) | — |
| Price per million tokens | |||
| Input | $0.75 (best) | $10.00 | $1.25 |
| Output | $3.75 (best) | $50.00 | $4.25 |
| Cached input | $0.075 (best) | $1.00 | $0.15 |
| Blended (3:1) | $1.50 (best) | $20.00 | $2.00 |
| Long-context rate | Same rate | Over 272K: $20.00 / $75.00 | Same rate |
| Price source | Official Google API | Official OpenAI API | Official Meta API |
| Limits | |||
| Context window | 1,048,576 tokens | 1,050,000 tokens (best) | 1,048,576 tokens |
| Max output | 65,536 tokens | 128,000 tokens | 131,072 tokens (best) |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | Yes | Yes | Yes |
| Audio | Yes | No | Yes |
| Video | Yes | No | Yes |
| Reasoning | Yeslow · medium · high | Yeslow · medium · high · xhigh · max | Yesminimal · low · medium · high · xhigh · max |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | Yes | Yes |
| Availability | |||
| Weights | Proprietary | Proprietary | Proprietary |
| API model ID | gemini-3.8-flash | gpt-6-astra | muse-spark-1.3 |
| API providers | 21 | 26 (best) | 12 |
| Released | Sep 2, 2026 | 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.
- Gemini 3.8 Flash$15.00
- GPT-6 Astra$200.00
- Muse Spark 1.3$21.00
Which should you choose?
Which is better: Gemini 3.8 Flash, GPT-6 Astra or Muse Spark 1.3?
It is close. Our weighted score puts them within 2 points (Gemini 3.8 Flash 75/100, Muse Spark 1.3 73/100, GPT-6 Astra 68/100), so choose by what matters most for your work: GPT-6 Astra for raw capability and Gemini 3.8 Flash on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, Gemini 3.8 Flash, GPT-6 Astra or Muse Spark 1.3?
Gemini 3.8 Flash is cheaper at $0.75 input / $3.75 output per million tokens (official Google API price). Muse Spark 1.3 costs $1.25 input / $4.25 output per million tokens (official Meta 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 $2.00 for Muse Spark 1.3 (1.3× as much) and $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), Gemini 3.8 Flash 156.9 (#15 of 148) and Muse Spark 1.3 156.9 (#17 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: FrontierMath Tiers 1–3 — GPT-6 Astra 93.7%, Muse Spark 1.3 74.4%, Gemini 3.8 Flash 68.4%; OTIS Mock AIME 2024–2025 — GPT-6 Astra 100%, Muse Spark 1.3 99.2%, Gemini 3.8 Flash 98.9%.
Which is better for coding?
There are no published SWE-bench Verified results for Gemini 3.8 Flash, GPT-6 Astra and Muse Spark 1.3 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. All three support tool calling for agent workflows.
Which has the bigger context window?
Their context windows are effectively the same size: Gemini 3.8 Flash 1,048,576, GPT-6 Astra 1,050,000 and Muse Spark 1.3 1,048,576 tokens. Maximum output per response: Gemini 3.8 Flash up to 65,536, GPT-6 Astra up to 128,000, Muse Spark 1.3 up to 131,072 tokens.
Which can read images, PDFs, audio or video?
Gemini 3.8 Flash accepts text, images, PDFs, audio and video; GPT-6 Astra accepts text, images and PDFs; Muse Spark 1.3 accepts text, images, PDFs, audio and video. Gemini 3.8 Flash handles the widest range of inputs.
Are any of these open source?
No. Gemini 3.8 Flash, GPT-6 Astra and Muse Spark 1.3 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; Muse Spark 1.3 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.
