GPT-5.6 Luna vs GLM-5.3-Flash vs DeepSeek V4.1 Flash
Too close to call on our weighted score (GLM-5.3-Flash 80, DeepSeek V4.1 Flash 78, GPT-5.6 Luna 78). The right pick depends on what you value most.
OpenAIGPT-5.6 Luna
78/100- ECI156.5
- Price$0.20 / $1.20
- Context1.05M
Z.ai (Zhipu)GLM-5.3-Flash
80/100- ECI151.9
- Price$0.15 / $0.50
- Context1M
DeepSeekDeepSeek V4.1 Flash
78/100- ECI155.0
- Price$0.15 / $0.60
- Context1M
Too close to call
It is close. Our weighted score puts them within 2 points (GLM-5.3-Flash 80/100, DeepSeek V4.1 Flash 78/100, GPT-5.6 Luna 78/100), so choose by what matters most for your work: GPT-5.6 Luna for raw capability and GLM-5.3-Flash on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
- CapabilityGPT-5.6 LunaCapabilities Index (ECI): GPT-5.6 Luna 156.5 · DeepSeek V4.1 Flash 155.0 · GLM-5.3-Flash 151.9
- Lowest priceGLM-5.3-FlashGLM-5.3-Flash $0.237 · DeepSeek V4.1 Flash $0.263 · GPT-5.6 Luna $0.45 per 1M tokens (3:1 blend)
- Longest contextGPT-5.6 LunaGPT-5.6 Luna 1,050,000 · GLM-5.3-Flash 1,000,000 · DeepSeek V4.1 Flash 1,000,000 tokens
- Widest inputsGLM-5.3-FlashGPT-5.6 Luna: Text, Images, PDFs · GLM-5.3-Flash: Text, Images, PDFs, Video · DeepSeek V4.1 Flash: Text, Images
- Self-hostingGLM-5.3-Flash and DeepSeek V4.1 FlashPublishes downloadable weights (MIT)
| Measure | Weight | GPT-5.6 Luna | GLM-5.3-Flash | DeepSeek V4.1 Flash |
|---|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 86 | 81 | 84 |
| Price | 25% | 66 | 79 | 77 |
| Inputs & features | 15% | 80 | 90 | 70 |
| Context window | 10% | 61 | 60 | 60 |
| Overall | 100% | 78/100 | 80/100 | 78/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | GPT-5.6 LunaOpenAI | GLM-5.3-FlashZ.ai (Zhipu) | DeepSeek V4.1 FlashDeepSeek |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 156.5 (best) | 151.9 | 155.0 |
| ECI rank | #21 of 148 (best) | #42 of 148 | #29 of 148 |
| GPQA DiamondGraduate-level science questions | 91.6% (best) | 90.2% | — |
| FrontierMath Tiers 1–3Research-level mathematics | 82.1% (best) | 55.8% | — |
| OTIS Mock AIME 2024–2025Competition mathematics | 98.3% (best) | 93.9% | — |
| SimpleQA VerifiedShort factual questions | 41.0% | — | — |
| Price per million tokens | |||
| Input | $0.20 | $0.15 (best) | $0.15 (best) |
| Output | $1.20 | $0.50 (best) | $0.60 |
| Cached input | $0.02 | $0.03 | $0.003 (best) |
| Blended (3:1) | $0.45 | $0.237 (best) | $0.263 |
| Long-context rate | Over 272K: $0.40 / $1.80 | Same rate | Same rate |
| Price source | Official OpenAI API | Official Z.AI API | Official DeepSeek API |
| Limits | |||
| Context window | 1,050,000 tokens (best) | 1,000,000 tokens | 1,000,000 tokens |
| Max output | 128,000 tokens | 131,072 tokens | 384,000 tokens (best) |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | Yes | Yes | No |
| Audio | No | No | No |
| Video | No | Yes | No |
| Reasoning | Yeslow · medium · high · xhigh · max | Yeslow · high · max | Yeslow · high · max |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | Yes | Yes |
| Availability | |||
| Weights | Proprietary | Open | OpenMIT |
| API model ID | gpt-5.6-luna | glm-5.3-flash | deepseek-flash |
| API providers | 38 | 65 (best) | 50 |
| Released | Jul 9, 2026 | Aug 26, 2026 | Sep 10, 2026 |
| Knowledge cutoff | Feb 16, 2026 | — | May 2025 |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- GPT-5.6 Luna$4.40
- GLM-5.3-Flash$2.50
- DeepSeek V4.1 Flash$2.70
Which should you choose?
Which is better: GPT-5.6 Luna, GLM-5.3-Flash or DeepSeek V4.1 Flash?
It is close. Our weighted score puts them within 2 points (GLM-5.3-Flash 80/100, DeepSeek V4.1 Flash 78/100, GPT-5.6 Luna 78/100), so choose by what matters most for your work: GPT-5.6 Luna for raw capability and GLM-5.3-Flash on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, GPT-5.6 Luna, GLM-5.3-Flash or DeepSeek V4.1 Flash?
GLM-5.3-Flash is cheaper at $0.15 input / $0.50 output per million tokens (official Z.AI API price). DeepSeek V4.1 Flash costs $0.15 input / $0.60 output per million tokens (official DeepSeek API price); GPT-5.6 Luna costs $0.20 input / $1.20 output per million tokens (official OpenAI API price). At a typical mix of three input tokens to one output token, that is $0.237 per million tokens for GLM-5.3-Flash versus $0.263 for DeepSeek V4.1 Flash (1.1× as much) and $0.45 for GPT-5.6 Luna (1.9× as much).
Which scores higher on benchmarks?
GPT-5.6 Luna scores higher on the Capabilities Index (ECI): GPT-5.6 Luna 156.5 (#21 of 148), DeepSeek V4.1 Flash 155.0 (#29 of 148) and GLM-5.3-Flash 151.9 (#42 of 148). The confidence ranges of the top two overlap (154.1–158.6 vs 148.8–157.6), so treat the gap as small.
Which is better for coding?
There are no published SWE-bench Verified results for GPT-5.6 Luna, GLM-5.3-Flash and DeepSeek V4.1 Flash yet, so there is no like-for-like coding score. On overall capability, GPT-5.6 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-5.6 Luna has the largest context window at 1,050,000 tokens, against 1,000,000 for GLM-5.3-Flash and 1,000,000 for DeepSeek V4.1 Flash. Maximum output per response: GPT-5.6 Luna up to 128,000, GLM-5.3-Flash up to 131,072, DeepSeek V4.1 Flash up to 384,000 tokens.
Which can read images, PDFs, audio or video?
GPT-5.6 Luna accepts text, images and PDFs; GLM-5.3-Flash accepts text, images, PDFs and video; DeepSeek V4.1 Flash accepts text and images. GLM-5.3-Flash handles the widest range of inputs.
Are any of these open source?
GLM-5.3-Flash and DeepSeek V4.1 Flash publishes its weights (MIT) and can be self-hosted; GPT-5.6 Luna is proprietary.
Which is newer?
DeepSeek V4.1 Flash is the newest, released Sep 10, 2026. GLM-5.3-Flash came out Aug 26, 2026; GPT-5.6 Luna came out Jul 9, 2026. Knowledge cutoff: GPT-5.6 Luna Feb 16, 2026, DeepSeek V4.1 Flash May 2025.
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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