Gemini 2.5 Flash vs Claude Sonnet 3.5 v2 vs DeepSeek-V3.1
Gemini 2.5 Flash comes out ahead, 68 to 55 and 44 on our weighted score, though DeepSeek-V3.1 is 29% cheaper per token.
- Our pick
GoogleGemini 2.5 Flash
68/100- ECI140.8
- Price$0.30 / $2.50
- Context1.05M
AnthropicClaude Sonnet 3.5 v2
44/100- ECI133.5
- Price$3.00 / $15.00
- Context200K
DeepSeekDeepSeek-V3.1
55/100- ECI139.9
- Price$0.385 / $1.25
- Context131K
Gemini 2.5 Flash is our pick
Gemini 2.5 Flash is the better all-round choice, scoring 68/100 against DeepSeek-V3.1 (55) and Claude Sonnet 3.5 v2 (44). It leads on inputs & features and context window. DeepSeek-V3.1 wins on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
- CapabilityGemini 2.5 FlashCapabilities Index (ECI): Gemini 2.5 Flash 140.8 · DeepSeek-V3.1 139.9 · Claude Sonnet 3.5 v2 133.5
- Lowest priceDeepSeek-V3.1DeepSeek-V3.1 $0.601 · Gemini 2.5 Flash $0.85 · Claude Sonnet 3.5 v2 $6.00 per 1M tokens (3:1 blend)
- Longest contextGemini 2.5 FlashGemini 2.5 Flash 1,048,576 · Claude Sonnet 3.5 v2 200,000 · DeepSeek-V3.1 131,072 tokens
- Widest inputsGemini 2.5 FlashGemini 2.5 Flash: Text, Images, PDFs, Audio, Video · Claude Sonnet 3.5 v2: Text, Images, PDFs · DeepSeek-V3.1: Text
- Self-hostingDeepSeek-V3.1Publishes downloadable weights (MIT License)
| Measure | Weight | Gemini 2.5 Flash | Claude Sonnet 3.5 v2 | DeepSeek-V3.1 |
|---|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 67 | 57 | 65 |
| Price | 25% | 53 | 13 | 60 |
| Inputs & features | 15% | 100 | 60 | 35 |
| Context window | 10% | 61 | 32 | 24 |
| Overall | 100% | 68/100 | 44/100 | 55/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | Gemini 2.5 FlashGoogle | Claude Sonnet 3.5 v2Anthropic | DeepSeek-V3.1DeepSeek |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 140.8 (best) | 133.5 | 139.9 |
| ECI rank | #97 of 148 (best) | #119 of 148 | #100 of 148 |
| GPQA DiamondGraduate-level science questions | — | 55.3% | — |
| OTIS Mock AIME 2024–2025Competition mathematics | — | 8.5% | — |
| Price per million tokens | |||
| Input | $0.30 (best) | $3.00 | $0.385 |
| Output | $2.50 | $15.00 | $1.25 (best) |
| Cached input | $0.03 | — | — |
| Blended (3:1) | $0.85 | $6.00 | $0.601 (best) |
| Long-context rate | Same rate | Same rate | Same rate |
| Price source | Official Google API | Median of 1 providers | Median of 8 providers |
| Limits | |||
| Context window | 1,048,576 tokens (best) | 200,000 tokens | 131,072 tokens |
| Max output | 65,536 tokens (best) | 8,192 tokens | 8,192 tokens |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | No |
| PDFs | Yes | Yes | No |
| Audio | Yes | No | No |
| Video | Yes | No | No |
| Reasoning | Yes | No | Yes |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | No | No |
| Availability | |||
| Weights | Proprietary | Proprietary | OpenMIT License |
| API model ID | gemini-2.5-flash | — | — |
| API providers | 22 (best) | 1 | 8 |
| Released | Jun 17, 2025 | Oct 22, 2024 | Aug 21, 2025 |
| Knowledge cutoff | Jan 2025 | Apr 30, 2024 | — |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- Gemini 2.5 Flash$8.00
- Claude Sonnet 3.5 v2$60.00
- DeepSeek-V3.1$6.35
Which should you choose?
Which is better: Gemini 2.5 Flash, Claude Sonnet 3.5 v2 or DeepSeek-V3.1?
Gemini 2.5 Flash is the better all-round choice, scoring 68/100 against DeepSeek-V3.1 (55) and Claude Sonnet 3.5 v2 (44). It leads on inputs & features and context window. DeepSeek-V3.1 wins on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, Gemini 2.5 Flash, Claude Sonnet 3.5 v2 or DeepSeek-V3.1?
DeepSeek-V3.1 is cheaper at $0.385 input / $1.25 output per million tokens (median across 8 API providers). Gemini 2.5 Flash costs $0.30 input / $2.50 output per million tokens (official Google API price); Claude Sonnet 3.5 v2 costs $3.00 input / $15.00 output per million tokens (median across 1 API provider). At a typical mix of three input tokens to one output token, that is $0.601 per million tokens for DeepSeek-V3.1 versus $0.85 for Gemini 2.5 Flash (1.4× as much) and $6.00 for Claude Sonnet 3.5 v2 (10× as much).
Which scores higher on benchmarks?
Gemini 2.5 Flash scores higher on the Capabilities Index (ECI): Gemini 2.5 Flash 140.8 (#97 of 148), DeepSeek-V3.1 139.9 (#100 of 148) and Claude Sonnet 3.5 v2 133.5 (#119 of 148). The confidence ranges of the top two overlap (138.5–142.3 vs 136.1–143.3), so treat the gap as small.
Which is better for coding?
There are no published SWE-bench Verified results for Gemini 2.5 Flash, Claude Sonnet 3.5 v2 and DeepSeek-V3.1 yet, so there is no like-for-like coding score. On overall capability, Gemini 2.5 Flash 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?
Gemini 2.5 Flash has the largest context window at 1,048,576 tokens, against 200,000 for Claude Sonnet 3.5 v2 and 131,072 for DeepSeek-V3.1. Maximum output per response: Gemini 2.5 Flash up to 65,536, Claude Sonnet 3.5 v2 up to 8,192, DeepSeek-V3.1 up to 8,192 tokens.
Which can read images, PDFs, audio or video?
Gemini 2.5 Flash accepts text, images, PDFs, audio and video; Claude Sonnet 3.5 v2 accepts text, images and PDFs; DeepSeek-V3.1 accepts text. Gemini 2.5 Flash handles the widest range of inputs.
Are any of these open source?
DeepSeek-V3.1 publishes its weights (MIT License) and can be self-hosted; Gemini 2.5 Flash and Claude Sonnet 3.5 v2 is proprietary.
Which is newer?
DeepSeek-V3.1 is the newest, released Aug 21, 2025. Gemini 2.5 Flash came out Jun 17, 2025; Claude Sonnet 3.5 v2 came out Oct 22, 2024. Knowledge cutoff: Gemini 2.5 Flash Jan 2025, Claude Sonnet 3.5 v2 Apr 30, 2024.
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.
Related comparisons
- Gemini 2.5 Flash vs Qwen3 235B-A22BAlibaba (Qwen) · ECI 139.4
- Gemini 2.5 Flash vs GPT-5 MiniOpenAI · ECI 145.5
- Gemini 2.5 Flash vs GLM-4.7Z.ai (Zhipu) · ECI 143.5
- Claude Sonnet 3.5 v2 vs Gemini 2.0 FlashGoogle · ECI 134.7
- Claude Sonnet 3.5 v2 vs GPT-4.1OpenAI · ECI 136.8
- Claude Sonnet 3.5 v2 vs Mistral Large 2.1Mistral AI · ECI 128.5
