Claude Haiku 5.5 vs Mercury 2.5 vs DeepSeek V4.1 Flash 1017
Claude Haiku 5.5 comes out ahead, 76 to 70 and 55 on our weighted score, and it is the cheaper option too.
- Our pick
AnthropicClaude Haiku 5.5
76/100- ECI160.4
- Price$0.10 / $0.50
- Context1M
InceptionMercury 2.5
55/100- ECI—
- Price$0.20 / $0.75
- Context260K
DeepSeekDeepSeek V4.1 Flash 1017
70/100- ECI158.8
- Price$0.15 / $0.60
- Context1M
Claude Haiku 5.5 is our pick
Claude Haiku 5.5 is the better all-round choice, scoring 76/100 against DeepSeek V4.1 Flash 1017 (70) and Mercury 2.5 (55). It leads on price and inputs & features. The score weighs price 50%, inputs & features 30%, context window 20%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.
- CapabilityNot enough dataNo independent benchmark covers every model here yet
- Lowest priceClaude Haiku 5.5Claude Haiku 5.5 $0.20 · DeepSeek V4.1 Flash 1017 $0.263 · Mercury 2.5 $0.338 per 1M tokens (3:1 blend)
- Longest contextClaude Haiku 5.5 and DeepSeek V4.1 Flash 1017Claude Haiku 5.5 1,000,000 · DeepSeek V4.1 Flash 1017 1,000,000 · Mercury 2.5 260,000 tokens
- Widest inputsClaude Haiku 5.5Claude Haiku 5.5: Text, Images, PDFs · Mercury 2.5: Text · DeepSeek V4.1 Flash 1017: Text, Images
- Self-hostingDeepSeek V4.1 Flash 1017Publishes downloadable weights (MIT)
| Measure | Weight | Claude Haiku 5.5 | Mercury 2.5 | DeepSeek V4.1 Flash 1017 |
|---|---|---|---|---|
| Price | 50% | 80 | 69 | 74 |
| Inputs & features | 30% | 80 | 45 | 70 |
| Context window | 20% | 60 | 36 | 60 |
| Overall | 100% | 76/100 | 55/100 | 70/100 |
Left out because at least one model lacks the data: capability. The remaining weights were rescaled.
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | Claude Haiku 5.5Anthropic | Mercury 2.5Inception | DeepSeek V4.1 Flash 1017DeepSeek |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 160.4 (best) | — | 158.8 |
| ECI rank | #14 of 165 (best) | — | #19 of 165 |
| GPQA DiamondGraduate-level science questions | 89.7% | — | 93.2% (best) |
| FrontierMath Tiers 1–3Research-level mathematics | 75.1% (best) | — | 71.2% |
| OTIS Mock AIME 2024–2025Competition mathematics | 98.9% | — | 99.4% (best) |
| SimpleQA VerifiedShort factual questions | 23.8% | — | 42.5% (best) |
| Price per million tokens | |||
| Input | $0.10 (best) | $0.20 | $0.15 |
| Output | $0.50 (best) | $0.75 | $0.60 |
| Cached input | $0.01 | $0.02 | $0.003 (best) |
| Blended (3:1) | $0.20 (best) | $0.338 | $0.263 |
| Long-context rate | Over 100K: $0.50 / $2.50 | Same rate | Same rate |
| Price source | Official Anthropic API | Official Inception API | Official DeepSeek API |
| Limits | |||
| Context window | 1,000,000 tokens (best) | 260,000 tokens | 1,000,000 tokens (best) |
| Max output | 128,000 tokens | 65,536 tokens | 384,000 tokens (best) |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | No | Yes |
| PDFs | Yes | No | No |
| Audio | No | No | No |
| Video | No | No | No |
| Reasoning | Yeslow · medium · high · xhigh · max | Yeslow · medium · high | Yeslow · high · max |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | Yes | Yes |
| Availability | |||
| Weights | Proprietary | Proprietary | OpenMIT |
| API model ID | claude-haiku-5-5 | mercury-2.5 | deepseek-flash |
| API providers | 33 | 6 | 40 (best) |
| Released | Oct 7, 2026 | Sep 8, 2026 | Oct 17, 2026 |
| Knowledge cutoff | Jun 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.
- Claude Haiku 5.5$2.00
- Mercury 2.5$3.50
- DeepSeek V4.1 Flash 1017$2.70
Which should you choose?
Which is better: Claude Haiku 5.5, Mercury 2.5 or DeepSeek V4.1 Flash 1017?
Claude Haiku 5.5 is the better all-round choice, scoring 76/100 against DeepSeek V4.1 Flash 1017 (70) and Mercury 2.5 (55). It leads on price and inputs & features. The score weighs price 50%, inputs & features 30%, context window 20%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.
Which is cheaper, Claude Haiku 5.5, Mercury 2.5 or DeepSeek V4.1 Flash 1017?
Claude Haiku 5.5 is cheaper at $0.10 input / $0.50 output per million tokens (official Anthropic API price). DeepSeek V4.1 Flash 1017 costs $0.15 input / $0.60 output per million tokens (official DeepSeek API price); Mercury 2.5 costs $0.20 input / $0.75 output per million tokens (official Inception API price). At a typical mix of three input tokens to one output token, that is $0.20 per million tokens for Claude Haiku 5.5 versus $0.263 for DeepSeek V4.1 Flash 1017 (1.3× as much) and $0.338 for Mercury 2.5 (1.7× as much).
Which scores higher on benchmarks?
There is no independent benchmark that covers all three models yet. Claude Haiku 5.5 has an ECI of 160.4, Mercury 2.5 has not been scored yet and DeepSeek V4.1 Flash 1017 has an ECI of 158.8.
Which is better for coding?
There are no published SWE-bench Verified results for Claude Haiku 5.5, Mercury 2.5 and DeepSeek V4.1 Flash 1017 yet, so there is no like-for-like coding score. Test both on a sample of your own tasks. All three support tool calling for agent workflows.
Which has the bigger context window?
Claude Haiku 5.5 and DeepSeek V4.1 Flash 1017 have the largest context windows (1,000,000 and 1,000,000 tokens), against 260,000 for Mercury 2.5. Maximum output per response: Claude Haiku 5.5 up to 128,000, Mercury 2.5 up to 65,536, DeepSeek V4.1 Flash 1017 up to 384,000 tokens.
Which can read images, PDFs, audio or video?
Claude Haiku 5.5 accepts text, images and PDFs; Mercury 2.5 accepts text; DeepSeek V4.1 Flash 1017 accepts text and images. Claude Haiku 5.5 handles the widest range of inputs.
Are any of these open source?
DeepSeek V4.1 Flash 1017 publishes its weights (MIT) and can be self-hosted; Claude Haiku 5.5 and Mercury 2.5 is proprietary.
Which is newer?
DeepSeek V4.1 Flash 1017 is the newest, released Oct 17, 2026. Claude Haiku 5.5 came out Oct 7, 2026; Mercury 2.5 came out Sep 8, 2026. Knowledge cutoff: Claude Haiku 5.5 Jun 2026, DeepSeek V4.1 Flash 1017 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 Nov 2, 2026.
