Qwen3.5 Flash vs GPT-6 Luna vs Gemma 4 31B IT
GPT-6 Luna comes out ahead, 77 to 71 and 61 on our weighted score, though Qwen3.5 Flash is 13% cheaper per token.
Alibaba (Qwen)Qwen3.5 Flash
71/100- ECI144.0
- Price$0.10 / $0.40
- Context1M
- Our pick
OpenAIGPT-6 Luna
77/100- ECI—
- Price$0.10 / $0.50
- Context1.05M
GoogleGemma 4 31B IT
61/100- ECI142.8
- Price$0.14 / $0.40
- Context262K
GPT-6 Luna is our pick
GPT-6 Luna is the better all-round choice, scoring 77/100 against Qwen3.5 Flash (71) and Gemma 4 31B IT (61). It leads on capability. Qwen3.5 Flash wins on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%. Capability uses the average of shared benchmarks (GPQA Diamond, OTIS Mock AIME 2024–2025 and SimpleQA Verified), because GPT-6 Luna has no Capabilities Index score yet.
- CapabilityGPT-6 LunaShared benchmarks: GPT-6 Luna 76.9% · Qwen3.5 Flash 62.4% · Gemma 4 31B IT 53.2%
- Lowest priceQwen3.5 FlashQwen3.5 Flash $0.175 · GPT-6 Luna $0.20 · Gemma 4 31B IT $0.205 per 1M tokens (3:1 blend)
- Longest contextGPT-6 LunaGPT-6 Luna 1,050,000 · Qwen3.5 Flash 1,000,000 · Gemma 4 31B IT 262,144 tokens
- Widest inputsQwen3.5 Flash and GPT-6 LunaQwen3.5 Flash: Text, Images, Video · GPT-6 Luna: Text, Images, PDFs · Gemma 4 31B IT: Text, Images
- Self-hostingGemma 4 31B ITPublishes downloadable weights
| Measure | Weight | Qwen3.5 Flash | GPT-6 Luna | Gemma 4 31B IT |
|---|---|---|---|---|
| CapabilityShared benchmarks | 50% | 62 | 77 | 53 |
| Price | 25% | 86 | 83 | 83 |
| Inputs & features | 15% | 80 | 80 | 70 |
| Context window | 10% | 60 | 61 | 37 |
| Overall | 100% | 71/100 | 77/100 | 61/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | Qwen3.5 FlashAlibaba (Qwen) | GPT-6 LunaOpenAI | Gemma 4 31B ITGoogle |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 144.0 (best) | — | 142.8 |
| ECI rank | #82 of 148 (best) | — | #86 of 148 |
| GPQA DiamondGraduate-level science questions | 82.3% | 90.5% (best) | 75.8% |
| FrontierMath Tiers 1–3Research-level mathematics | 18.3% | 79.0% (best) | — |
| OTIS Mock AIME 2024–2025Competition mathematics | 84.4% | 98.9% (best) | 73.3% |
| SimpleQA VerifiedShort factual questions | 20.3% | 41.4% (best) | 10.4% |
| Price per million tokens | |||
| Input | $0.10 (best) | $0.10 (best) | $0.14 |
| Output | $0.40 (best) | $0.50 | $0.40 (best) |
| Cached input | $0.01 | $0.01 | — |
| Blended (3:1) | $0.175 (best) | $0.20 | $0.205 |
| Long-context rate | Same rate | Over 272K: $0.20 / $0.75 | Same rate |
| Price source | Official Alibaba API | Official OpenAI API | Median of 30 providers |
| Limits | |||
| Context window | 1,000,000 tokens | 1,050,000 tokens (best) | 262,144 tokens |
| Max output | 65,536 tokens | 128,000 tokens (best) | 32,768 tokens |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | No | Yes | No |
| Audio | No | No | No |
| Video | Yes | No | No |
| Reasoning | Yes | Yeslow · medium · high · xhigh · max | Yes |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | Yes | Yes |
| Availability | |||
| Weights | Proprietary | Proprietary | Open |
| API model ID | qwen3.5-flash | gpt-6-luna | gemma-4-31b-it |
| API providers | 8 | 24 | 38 (best) |
| Released | Feb 23, 2026 | Sep 22, 2026 | Apr 2, 2026 |
| Knowledge cutoff | — | May 18, 2026 | — |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- Qwen3.5 Flash$1.80
- GPT-6 Luna$2.00
- Gemma 4 31B IT$2.20
Which should you choose?
Which is better: Qwen3.5 Flash, GPT-6 Luna or Gemma 4 31B IT?
GPT-6 Luna is the better all-round choice, scoring 77/100 against Qwen3.5 Flash (71) and Gemma 4 31B IT (61). It leads on capability. Qwen3.5 Flash wins on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%. Capability uses the average of shared benchmarks (GPQA Diamond, OTIS Mock AIME 2024–2025 and SimpleQA Verified), because GPT-6 Luna has no Capabilities Index score yet.
Which is cheaper, Qwen3.5 Flash, GPT-6 Luna or Gemma 4 31B IT?
Qwen3.5 Flash is cheaper at $0.10 input / $0.40 output per million tokens (official Alibaba API price). GPT-6 Luna costs $0.10 input / $0.50 output per million tokens (official OpenAI API price); Gemma 4 31B IT costs $0.14 input / $0.40 output per million tokens (median across 30 API providers). At a typical mix of three input tokens to one output token, that is $0.175 per million tokens for Qwen3.5 Flash versus $0.20 for GPT-6 Luna (1.1× as much) and $0.205 for Gemma 4 31B IT (1.2× as much).
Which scores higher on benchmarks?
Not every model here has a Capabilities Index score, so we compare the average of shared benchmarks (GPQA Diamond, OTIS Mock AIME 2024–2025 and SimpleQA Verified): GPT-6 Luna 76.9%, Qwen3.5 Flash 62.4% and Gemma 4 31B IT 53.2%. On individual benchmarks: GPQA Diamond — GPT-6 Luna 90.5%, Qwen3.5 Flash 82.3%, Gemma 4 31B IT 75.8%; OTIS Mock AIME 2024–2025 — GPT-6 Luna 98.9%, Qwen3.5 Flash 84.4%, Gemma 4 31B IT 73.3%; SimpleQA Verified — GPT-6 Luna 41.4%, Qwen3.5 Flash 20.3%, Gemma 4 31B IT 10.4%.
Which is better for coding?
There are no published SWE-bench Verified results for Qwen3.5 Flash, GPT-6 Luna and Gemma 4 31B IT yet, so there is no like-for-like coding score. On overall capability, GPT-6 Luna 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?
GPT-6 Luna has the largest context window at 1,050,000 tokens, against 1,000,000 for Qwen3.5 Flash and 262,144 for Gemma 4 31B IT. Maximum output per response: Qwen3.5 Flash up to 65,536, GPT-6 Luna up to 128,000, Gemma 4 31B IT up to 32,768 tokens.
Which can read images, PDFs, audio or video?
Qwen3.5 Flash accepts text, images and video; GPT-6 Luna accepts text, images and PDFs; Gemma 4 31B IT accepts text and images. Qwen3.5 Flash handles the widest range of inputs.
Are any of these open source?
Gemma 4 31B IT publishes its weights and can be self-hosted; Qwen3.5 Flash and GPT-6 Luna is proprietary.
Which is newer?
GPT-6 Luna is the newest, released Sep 22, 2026. Gemma 4 31B IT came out Apr 2, 2026; Qwen3.5 Flash came out Feb 23, 2026. Knowledge cutoff: GPT-6 Luna May 18, 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.
