DeepSeek V4.1 Flash vs Claude Sonnet 5.5 vs GLM-5.3-Flash
Too close to call on our weighted score (GLM-5.3-Flash 80, DeepSeek V4.1 Flash 78, Claude Sonnet 5.5 72). The right pick depends on what you value most.
DeepSeekDeepSeek V4.1 Flash
78/100- ECI155.0
- Price$0.15 / $0.60
- Context1M
AnthropicClaude Sonnet 5.5
72/100- ECI165.2
- Price$2.00 / $10.00
- Context1M
Z.ai (Zhipu)GLM-5.3-Flash
80/100- ECI151.9
- Price$0.15 / $0.50
- 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, Claude Sonnet 5.5 72/100), so choose by what matters most for your work: Claude Sonnet 5.5 for raw capability and GLM-5.3-Flash on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
- CapabilityClaude Sonnet 5.5Capabilities Index (ECI): Claude Sonnet 5.5 165.2 · 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 · Claude Sonnet 5.5 $4.00 per 1M tokens (3:1 blend)
- Longest contextAbout the sameDeepSeek V4.1 Flash 1,000,000 · Claude Sonnet 5.5 1,000,000 · GLM-5.3-Flash 1,000,000 tokens
- Widest inputsGLM-5.3-FlashDeepSeek V4.1 Flash: Text, Images · Claude Sonnet 5.5: Text, Images, PDFs · GLM-5.3-Flash: Text, Images, PDFs, Video
- Self-hostingDeepSeek V4.1 Flash and GLM-5.3-FlashPublishes downloadable weights (MIT)
| Measure | Weight | DeepSeek V4.1 Flash | Claude Sonnet 5.5 | GLM-5.3-Flash |
|---|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 84 | 97 | 81 |
| Price | 25% | 77 | 21 | 79 |
| Inputs & features | 15% | 70 | 80 | 90 |
| Context window | 10% | 60 | 60 | 60 |
| Overall | 100% | 78/100 | 72/100 | 80/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | DeepSeek V4.1 FlashDeepSeek | Claude Sonnet 5.5Anthropic | GLM-5.3-FlashZ.ai (Zhipu) |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 155.0 | 165.2 (best) | 151.9 |
| ECI rank | #29 of 148 | #3 of 148 (best) | #42 of 148 |
| GPQA DiamondGraduate-level science questions | — | 95.6% (best) | 90.2% |
| FrontierMath Tiers 1–3Research-level mathematics | — | 88.8% (best) | 55.8% |
| OTIS Mock AIME 2024–2025Competition mathematics | — | 100% (best) | 93.9% |
| SimpleQA VerifiedShort factual questions | — | 46.5% | — |
| Price per million tokens | |||
| Input | $0.15 (best) | $2.00 | $0.15 (best) |
| Output | $0.60 | $10.00 | $0.50 (best) |
| Cached input | $0.003 (best) | $0.20 | $0.03 |
| Blended (3:1) | $0.263 | $4.00 | $0.237 (best) |
| Long-context rate | Same rate | Same rate | Same rate |
| Price source | Official DeepSeek API | Official Anthropic API | Official Z.AI API |
| Limits | |||
| Context window | 1,000,000 tokens | 1,000,000 tokens | 1,000,000 tokens |
| Max output | 384,000 tokens (best) | 128,000 tokens | 131,072 tokens |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | No | Yes | Yes |
| Audio | No | No | No |
| Video | No | No | Yes |
| Reasoning | Yeslow · high · max | Yeslow · medium · high · xhigh · max | Yeslow · high · max |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | Yes | Yes |
| Availability | |||
| Weights | OpenMIT | Proprietary | Open |
| API model ID | deepseek-flash | claude-sonnet-5-5 | glm-5.3-flash |
| API providers | 50 | 23 | 65 (best) |
| Released | Sep 10, 2026 | Sep 28, 2026 | Aug 26, 2026 |
| Knowledge cutoff | May 2025 | Jun 2026 | — |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- DeepSeek V4.1 Flash$2.70
- Claude Sonnet 5.5$40.00
- GLM-5.3-Flash$2.50
Which should you choose?
Which is better: DeepSeek V4.1 Flash, Claude Sonnet 5.5 or GLM-5.3-Flash?
It is close. Our weighted score puts them within 2 points (GLM-5.3-Flash 80/100, DeepSeek V4.1 Flash 78/100, Claude Sonnet 5.5 72/100), so choose by what matters most for your work: Claude Sonnet 5.5 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, DeepSeek V4.1 Flash, Claude Sonnet 5.5 or GLM-5.3-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); Claude Sonnet 5.5 costs $2.00 input / $10.00 output per million tokens (official Anthropic 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 $4.00 for Claude Sonnet 5.5 (17× as much).
Which scores higher on benchmarks?
Claude Sonnet 5.5 scores higher on the Capabilities Index (ECI): Claude Sonnet 5.5 165.2 (#3 of 148), DeepSeek V4.1 Flash 155.0 (#29 of 148) and GLM-5.3-Flash 151.9 (#42 of 148). Their confidence ranges do not overlap (161.8–169.4 vs 148.8–157.6), so the gap is a real one.
Which is better for coding?
There are no published SWE-bench Verified results for DeepSeek V4.1 Flash, Claude Sonnet 5.5 and GLM-5.3-Flash yet, so there is no like-for-like coding score. On overall capability, Claude Sonnet 5.5 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?
DeepSeek V4.1 Flash, Claude Sonnet 5.5 and GLM-5.3-Flash share the same 1,000,000-token context window. Maximum output per response: DeepSeek V4.1 Flash up to 384,000, Claude Sonnet 5.5 up to 128,000, GLM-5.3-Flash up to 131,072 tokens.
Which can read images, PDFs, audio or video?
DeepSeek V4.1 Flash accepts text and images; Claude Sonnet 5.5 accepts text, images and PDFs; 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?
DeepSeek V4.1 Flash and GLM-5.3-Flash publishes its weights (MIT) and can be self-hosted; Claude Sonnet 5.5 is proprietary.
Which is newer?
Claude Sonnet 5.5 is the newest, released Sep 28, 2026. DeepSeek V4.1 Flash came out Sep 10, 2026; GLM-5.3-Flash came out Aug 26, 2026. Knowledge cutoff: DeepSeek V4.1 Flash May 2025, Claude Sonnet 5.5 Jun 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.
