GPT-6 Luna vs Gemma 4 31B IT vs GLM-5.3-Flash
Too close to call on our weighted score (GPT-6 Luna 86, GLM-5.3-Flash 85, Gemma 4 31B IT 72). The right pick depends on what you value most.
OpenAIGPT-6 Luna
86/100- ECI—
- Price$0.10 / $0.50
- Context1.05M
GoogleGemma 4 31B IT
72/100- ECI142.8
- Price$0.14 / $0.40
- Context262K
Z.ai (Zhipu)GLM-5.3-Flash
85/100- ECI151.9
- Price$0.15 / $0.50
- Context1M
Too close to call
It is close. Our weighted score puts them within a point (GPT-6 Luna 86/100, GLM-5.3-Flash 85/100, Gemma 4 31B IT 72/100), so choose by what matters most for your work: GPT-6 Luna for raw capability. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%. Capability uses the average of shared benchmarks (GPQA Diamond and OTIS Mock AIME 2024–2025), because GPT-6 Luna has no Capabilities Index score yet.
- CapabilityGPT-6 LunaShared benchmarks: GPT-6 Luna 94.7% · GLM-5.3-Flash 92.0% · Gemma 4 31B IT 74.5%
- Lowest priceGPT-6 LunaGPT-6 Luna $0.20 · Gemma 4 31B IT $0.205 · GLM-5.3-Flash $0.237 per 1M tokens (3:1 blend)
- Longest contextGPT-6 LunaGPT-6 Luna 1,050,000 · GLM-5.3-Flash 1,000,000 · Gemma 4 31B IT 262,144 tokens
- Widest inputsGLM-5.3-FlashGPT-6 Luna: Text, Images, PDFs · Gemma 4 31B IT: Text, Images · GLM-5.3-Flash: Text, Images, PDFs, Video
- Self-hostingGemma 4 31B IT and GLM-5.3-FlashPublishes downloadable weights
| Measure | Weight | GPT-6 Luna | Gemma 4 31B IT | GLM-5.3-Flash |
|---|---|---|---|---|
| CapabilityShared benchmarks | 50% | 95 | 75 | 92 |
| Price | 25% | 83 | 83 | 79 |
| Inputs & features | 15% | 80 | 70 | 90 |
| Context window | 10% | 61 | 37 | 60 |
| Overall | 100% | 86/100 | 72/100 | 85/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | GPT-6 LunaOpenAI | Gemma 4 31B ITGoogle | GLM-5.3-FlashZ.ai (Zhipu) |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | — | 142.8 | 151.9 (best) |
| ECI rank | — | #86 of 148 | #42 of 148 (best) |
| GPQA DiamondGraduate-level science questions | 90.5% (best) | 75.8% | 90.2% |
| FrontierMath Tiers 1–3Research-level mathematics | 79.0% (best) | — | 55.8% |
| OTIS Mock AIME 2024–2025Competition mathematics | 98.9% (best) | 73.3% | 93.9% |
| SimpleQA VerifiedShort factual questions | 41.4% (best) | 10.4% | — |
| Price per million tokens | |||
| Input | $0.10 (best) | $0.14 | $0.15 |
| Output | $0.50 | $0.40 (best) | $0.50 |
| Cached input | $0.01 (best) | — | $0.03 |
| Blended (3:1) | $0.20 (best) | $0.205 | $0.237 |
| Long-context rate | Over 272K: $0.20 / $0.75 | Same rate | Same rate |
| Price source | Official OpenAI API | Median of 30 providers | Official Z.AI API |
| Limits | |||
| Context window | 1,050,000 tokens (best) | 262,144 tokens | 1,000,000 tokens |
| Max output | 128,000 tokens | 32,768 tokens | 131,072 tokens (best) |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | Yes | No | Yes |
| Audio | No | No | No |
| Video | No | No | Yes |
| Reasoning | Yeslow · medium · high · xhigh · max | Yes | Yeslow · high · max |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | Yes | Yes |
| Availability | |||
| Weights | Proprietary | Open | Open |
| API model ID | gpt-6-luna | gemma-4-31b-it | glm-5.3-flash |
| API providers | 24 | 38 | 65 (best) |
| Released | Sep 22, 2026 | Apr 2, 2026 | Aug 26, 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.
- GPT-6 Luna$2.00
- Gemma 4 31B IT$2.20
- GLM-5.3-Flash$2.50
Which should you choose?
Which is better: GPT-6 Luna, Gemma 4 31B IT or GLM-5.3-Flash?
It is close. Our weighted score puts them within a point (GPT-6 Luna 86/100, GLM-5.3-Flash 85/100, Gemma 4 31B IT 72/100), so choose by what matters most for your work: GPT-6 Luna for raw capability. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%. Capability uses the average of shared benchmarks (GPQA Diamond and OTIS Mock AIME 2024–2025), because GPT-6 Luna has no Capabilities Index score yet.
Which is cheaper, GPT-6 Luna, Gemma 4 31B IT or GLM-5.3-Flash?
GPT-6 Luna is cheaper at $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); GLM-5.3-Flash costs $0.15 input / $0.50 output per million tokens (official Z.AI API price). At a typical mix of three input tokens to one output token, that is $0.20 per million tokens for GPT-6 Luna versus $0.205 for Gemma 4 31B IT (1× as much) and $0.237 for GLM-5.3-Flash (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 and OTIS Mock AIME 2024–2025): GPT-6 Luna 94.7%, GLM-5.3-Flash 92.0% and Gemma 4 31B IT 74.5%. On individual benchmarks: GPQA Diamond — GPT-6 Luna 90.5%, GLM-5.3-Flash 90.2%, Gemma 4 31B IT 75.8%; OTIS Mock AIME 2024–2025 — GPT-6 Luna 98.9%, GLM-5.3-Flash 93.9%, Gemma 4 31B IT 73.3%.
Which is better for coding?
There are no published SWE-bench Verified results for GPT-6 Luna, Gemma 4 31B IT and GLM-5.3-Flash 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 GLM-5.3-Flash and 262,144 for Gemma 4 31B IT. Maximum output per response: GPT-6 Luna up to 128,000, Gemma 4 31B IT up to 32,768, GLM-5.3-Flash up to 131,072 tokens.
Which can read images, PDFs, audio or video?
GPT-6 Luna accepts text, images and PDFs; Gemma 4 31B IT accepts text and images; GLM-5.3-Flash accepts text, images, PDFs and video. GLM-5.3-Flash handles the widest range of inputs.
Are any of these open source?
Gemma 4 31B IT and GLM-5.3-Flash publishes its weights and can be self-hosted; GPT-6 Luna is proprietary.
Which is newer?
GPT-6 Luna is the newest, released Sep 22, 2026. GLM-5.3-Flash came out Aug 26, 2026; Gemma 4 31B IT came out Apr 2, 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.
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