AI model comparison
Claude Sonnet 5.5 vs DeepSeek V4.1 Flash
Pricing, context window, benchmarks, and features compared side by side. Or skip the guesswork and send one prompt to both.
Anthropic
Claude Sonnet 5.5
Claude Sonnet 5.5 is Anthropic's Sonnet-class model for well-scoped everyday work, succeeding Claude Sonnet 5 as a direct upgrade.
- Input / 1M
- $2
- Output / 1M
- $10
- Context
- 1M
DeepSeek
DeepSeek V4.1 Flash
DeepSeek V4.1 Flash is a sparse mixture-of-experts model from DeepSeek, and the first built on the company's Causal Encoder-Decoder (CED) architecture.
- Input / 1M
- $0.30
- Output / 1M
- $1.20
- Context
- 1.05M
At a glance
Quick verdict
How the two models stack up on the things people ask about most.
Lower price
DeepSeek V4.1 Flash
7.5x cheaper for a typical chat
Higher intelligence score
Claude Sonnet 5.5
56 vs 39.5 on Artificial Analysis
Larger context window
DeepSeek V4.1 Flash
1.05M vs 1M tokens
Newer release
Claude Sonnet 5.5
Released September 28, 2026
Benchmarks
Benchmark scores
Independent scores from Artificial Analysis. Higher is better.
Intelligence index
Claude Sonnet 5.556DeepSeek V4.1 Flash39.5Coding index
Claude Sonnet 5.5Not availableDeepSeek V4.1 FlashNot availableAgentic index
Claude Sonnet 5.5Not availableDeepSeek V4.1 FlashNot availablePricing
Claude Sonnet 5.5 vs DeepSeek V4.1 Flash API pricing
Per-token API rates. Cheaper option highlighted.
| Metric | Claude Sonnet 5.5 | DeepSeek V4.1 Flash |
|---|---|---|
| Input tokensPer 1M tokens | $2 | $0.30 |
| Output tokensPer 1M tokens | $10 | $1.20 |
| Cached input (read)Per 1M tokens | $0.10 | $0.01 |
| Cache writePer 1M tokens | $2.50 | Not available |
| Web searchPer request | $0.01 | Not available |
What it costs in practice
Estimated cost per 1,000 requests at standard rates. Coding and long-document figures also show the cost when the input is already cached.
Chat message
2K in, 500 out
Claude Sonnet 5.5$9DeepSeek V4.1 Flash$1.20Coding task
30K in, 4K out
Claude Sonnet 5.5$100$43 cachedDeepSeek V4.1 Flash$13.80$4.98 cachedLong document summary
150K in, 2K out
Claude Sonnet 5.5$320$35 cachedDeepSeek V4.1 Flash$47.40$3.30 cachedSpecs
Context window and capabilities
How much each model can read, how much it can write, and what it accepts as input.
| Metric | Claude Sonnet 5.5 | DeepSeek V4.1 Flash |
|---|---|---|
| Context window | 1M tokens | 1.05M tokens |
| Max output | 128K tokens | 944K tokens |
| Input types | File, Image, Text | Image, Text |
| Output types | Text | Text |
| Reasoning effort levels | Max, Extra high, High, Medium, Low | Max, High, Low |
| Default reasoning effort | High | High |
| Release date | September 28, 2026 | September 10, 2026 |
Features
Supported features
API features available for each model.
| Metric | Claude Sonnet 5.5 | DeepSeek V4.1 Flash |
|---|---|---|
| Tool calling | Supported | Supported |
| Structured outputs | Supported | Supported |
| JSON mode | Supported | Supported |
| Reasoning | Supported | Supported |
| Temperature | Not supported | Supported |
| Stop sequences | Supported | Supported |
| Deterministic seed | Not supported | Supported |
| Verbosity control | Supported | Not supported |
Keep exploring
More on these models
Other head-to-heads, the full model page, and the alternatives list for each model.
Claude Sonnet 5.5View full model details- Claude Sonnet 5.5 vs Claude Opus 5.5
- Claude Sonnet 5.5 vs Claude Fable 5.1
- Claude Sonnet 5.5 vs GPT-6 Astra
- Claude Sonnet 5.5 vs GPT-6.1 Sol
- Claude Sonnet 5.5 vs Claude Opus 5
- Claude Sonnet 5.5 vs Claude Fable 5
- Claude Sonnet 5.5 vs Muse Spark 1.3
- Claude Sonnet 5.5 vs GPT-6 Sol
- Claude Sonnet 5.5 vs GPT-5.6 Sol
- Claude Sonnet 5.5 vs Grok 4.7
- Claude Sonnet 5.5 vs GLM 5.3
- Claude Sonnet 5.5 vs GLM 5.3 Flash
- Claude Sonnet 5.5 vs MiMo-V2.6-Flash
- Claude Sonnet 5.5 vs Hy4 preview
- Claude Sonnet 5.5 vs GPT-6 Luna
- Claude Sonnet 5.5 vs DeepSeek V4 Flash 0731
DeepSeek V4.1 FlashView full model details- DeepSeek V4.1 Flash vs GLM 5.3 Flash
- DeepSeek V4.1 Flash vs MiMo-V2.6-Flash
- DeepSeek V4.1 Flash vs Hy4 preview
- DeepSeek V4.1 Flash vs GPT-6 Luna
- DeepSeek V4.1 Flash vs DeepSeek V4 Flash 0731
- DeepSeek V4.1 Flash vs Claude Opus 5.5
- DeepSeek V4.1 Flash vs GLM 5.3
- DeepSeek V4.1 Flash vs DeepSeek V4 Flash 0423
- DeepSeek V4.1 Flash vs Step 5 Preview
- DeepSeek V4.1 Flash vs Gemini 3.8 Flash
- DeepSeek V4.1 Flash vs Hy3
- DeepSeek V4.1 Flash vs GPT-5.6 Luna
- DeepSeek V4.1 Flash vs GPT-6.1 Sol
- DeepSeek V4.1 Flash vs Muse Spark 1.3 Contributor
- DeepSeek V4.1 Flash vs GLM 5.2
- DeepSeek V4.1 Flash vs MiMo-V2.6-Pro
- DeepSeek V4.1 Flash vs MiniMax M3
- DeepSeek V4.1 Flash vs DeepSeek V4 Pro 0813
- DeepSeek V4.1 Flash vs GPT-6 Astra
- DeepSeek V4.1 Flash vs Claude Opus 5
- DeepSeek V4.1 Flash vs Claude Fable 5.1
- DeepSeek V4.1 Flash vs Claude Sonnet 5
- DeepSeek V4.1 Flash vs DeepSeek V4 Pro 0423
- DeepSeek V4.1 Flash vs Muse Spark 1.3
- DeepSeek V4.1 Flash vs GPT-6 Luna Pro
- DeepSeek V4.1 Flash vs Qwen3.8 Max (0902)
- DeepSeek V4.1 Flash vs Claude Haiku 5.5
- DeepSeek V4.1 Flash vs Qwen3.8 27B
- DeepSeek V4.1 Flash vs Grok 4.6
- DeepSeek V4.1 Flash vs Ling 3.1 Flash
- DeepSeek V4.1 Flash vs GPT-5.6 Terra
- DeepSeek V4.1 Flash vs Claude Opus 4.8
- DeepSeek V4.1 Flash vs Qwen3.8 Flash
- DeepSeek V4.1 Flash vs Gemini 3.7 Flash
- DeepSeek V4.1 Flash vs Qwen3.7 Flash
- DeepSeek V4.1 Flash vs Claude Opus 4.7
- DeepSeek V4.1 Flash vs Qwen3.8 2.4T A95B
- DeepSeek V4.1 Flash vs Muse Spark 1.2
- DeepSeek V4.1 Flash vs GPT-5.4
- DeepSeek V4.1 Flash vs Grok 4.5
- DeepSeek V4.1 Flash vs GPT-5.5
- DeepSeek V4.1 Flash vs DeepSeek V4 Flash Vision Exp
- DeepSeek V4.1 Flash vs GLM 5.3 FlashX
- DeepSeek V4.1 Flash vs Gemini 3.6 Flash
- DeepSeek V4.1 Flash vs Muse Spark 1.1
- DeepSeek V4.1 Flash vs GPT-5.6 Luna Pro
Our take
DeepSeek V4.1 Flash is 7.5x cheaper for a typical chat. Claude Sonnet 5.5 scores higher on the Artificial Analysis Intelligence Index (56 vs 39.5). DeepSeek V4.1 Flash has the larger context window (1.05M vs 1M tokens). The right pick depends on your workload, so the quickest way to settle it is to send the same prompt to both and compare.
FAQ
Frequently asked questions
Is Claude Sonnet 5.5 or DeepSeek V4.1 Flash cheaper?
DeepSeek V4.1 Flash is cheaper for a typical chat (2K input tokens and 500 output tokens). DeepSeek V4.1 Flash costs $0.30 per 1M input tokens and $1.20 per 1M output tokens, while Claude Sonnet 5.5 costs $2 per 1M input tokens and $10 per 1M output tokens.
Which has a bigger context window, Claude Sonnet 5.5 or DeepSeek V4.1 Flash?
DeepSeek V4.1 Flash supports up to 1.05M tokens of context, compared with 1M for Claude Sonnet 5.5.
Is Claude Sonnet 5.5 smarter than DeepSeek V4.1 Flash?
On the Artificial Analysis Intelligence Index, Claude Sonnet 5.5 scores 56 and DeepSeek V4.1 Flash scores 39.5, putting Claude Sonnet 5.5 ahead. Benchmarks don't capture everything, so the best test is running your own prompts through both.
Can I use Claude Sonnet 5.5 and DeepSeek V4.1 Flash at the same time?
Yes. Shortcut Chat sends one prompt to multiple models at once, so you can see Claude Sonnet 5.5 and DeepSeek V4.1 Flash answer side by side and keep the better response.
Why choose? Ask both.
Send one prompt to Claude Sonnet 5.5 and DeepSeek V4.1 Flash at the same time. Compare the answers side by side and keep the best one.