Gemini 3.5 Flash vs Grok 4.5 vs Claude Sonnet 5
Too close to call on our weighted score (Gemini 3.5 Flash 69, Claude Sonnet 5 66, Grok 4.5 64). The right pick depends on what you value most.
GoogleGemini 3.5 Flash
69/100- ECI154.5
- Price$1.50 / $9.00
- Context1.05M
xAIGrok 4.5
64/100- ECI154.0
- Price$2.00 / $6.00
- Context500K
AnthropicClaude Sonnet 5
66/100- ECI156.3
- Price$2.00 / $10.00
- Context1M
Too close to call
It is close. Our weighted score puts them within 3 points (Gemini 3.5 Flash 69/100, Claude Sonnet 5 66/100, Grok 4.5 64/100), so choose by what matters most for your work: Claude Sonnet 5 for raw capability, Grok 4.5 on price and Gemini 3.5 Flash for long inputs. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
- CapabilityClaude Sonnet 5Capabilities Index (ECI): Claude Sonnet 5 156.3 · Gemini 3.5 Flash 154.5 · Grok 4.5 154.0
- Lowest priceGrok 4.5Grok 4.5 $3.00 · Gemini 3.5 Flash $3.38 · Claude Sonnet 5 $4.00 per 1M tokens (3:1 blend)
- Longest contextGemini 3.5 FlashGemini 3.5 Flash 1,048,576 · Claude Sonnet 5 1,000,000 · Grok 4.5 500,000 tokens
- Widest inputsGemini 3.5 FlashGemini 3.5 Flash: Text, Images, PDFs, Audio, Video · Grok 4.5: Text, Images · Claude Sonnet 5: Text, Images, PDFs
- Self-hostingNo open weightsAll three are available only through APIs
| Measure | Weight | Gemini 3.5 Flash | Grok 4.5 | Claude Sonnet 5 |
|---|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 84 | 83 | 86 |
| Price | 25% | 25 | 27 | 21 |
| Inputs & features | 15% | 100 | 70 | 80 |
| Context window | 10% | 61 | 48 | 60 |
| Overall | 100% | 69/100 | 64/100 | 66/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | Gemini 3.5 FlashGoogle | Grok 4.5xAI | Claude Sonnet 5Anthropic |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 154.5 | 154.0 | 156.3 (best) |
| ECI rank | #33 of 148 | #36 of 148 | #23 of 148 (best) |
| GPQA DiamondGraduate-level science questions | 92.8% | 93.4% (best) | 90.5% |
| FrontierMath Tiers 1–3Research-level mathematics | 62.8% | 57.2% | 65.6% (best) |
| OTIS Mock AIME 2024–2025Competition mathematics | 95.6% | 97.8% (best) | 94.7% |
| SWE-bench VerifiedFixing real GitHub issues | 79.3% | — | — |
| SimpleQA VerifiedShort factual questions | 66.2% (best) | 48.3% | 33.7% |
| Price per million tokens | |||
| Input | $1.50 (best) | $2.00 | $2.00 |
| Output | $9.00 | $6.00 (best) | $10.00 |
| Cached input | $0.15 (best) | $0.30 | $0.20 |
| Blended (3:1) | $3.38 | $3.00 (best) | $4.00 |
| Long-context rate | Same rate | Over 200K: $4.00 / $12.00 | Same rate |
| Price source | Official Google API | Official xAI API | Official Anthropic API |
| Limits | |||
| Context window | 1,048,576 tokens (best) | 500,000 tokens | 1,000,000 tokens |
| Max output | 65,536 tokens | 500,000 tokens (best) | 128,000 tokens |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | Yes | No | Yes |
| Audio | Yes | No | No |
| Video | Yes | No | No |
| Reasoning | Yesminimal · low · medium · high | Yeslow · medium · high | Yeslow · medium · high · xhigh · max |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | Yes | Yes |
| Availability | |||
| Weights | Proprietary | Proprietary | Proprietary |
| API model ID | gemini-3.5-flash | grok-4.5 | claude-sonnet-5 |
| API providers | 32 | 24 | 38 (best) |
| Released | May 19, 2026 | Jul 8, 2026 | Jun 30, 2026 |
| Knowledge cutoff | Jan 2025 | — | Jan 31, 2026 |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- Gemini 3.5 Flash$33.00
- Grok 4.5$32.00
- Claude Sonnet 5$40.00
Which should you choose?
Which is better: Gemini 3.5 Flash, Grok 4.5 or Claude Sonnet 5?
It is close. Our weighted score puts them within 3 points (Gemini 3.5 Flash 69/100, Claude Sonnet 5 66/100, Grok 4.5 64/100), so choose by what matters most for your work: Claude Sonnet 5 for raw capability, Grok 4.5 on price and Gemini 3.5 Flash for long inputs. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, Gemini 3.5 Flash, Grok 4.5 or Claude Sonnet 5?
Grok 4.5 is cheaper at $2.00 input / $6.00 output per million tokens (official xAI API price). Gemini 3.5 Flash costs $1.50 input / $9.00 output per million tokens (official Google API price); Claude Sonnet 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 $3.00 per million tokens for Grok 4.5 versus $3.38 for Gemini 3.5 Flash (1.1× as much) and $4.00 for Claude Sonnet 5 (1.3× as much).
Which scores higher on benchmarks?
Claude Sonnet 5 scores higher on the Capabilities Index (ECI): Claude Sonnet 5 156.3 (#23 of 148), Gemini 3.5 Flash 154.5 (#33 of 148) and Grok 4.5 154.0 (#36 of 148). The confidence ranges of the top two overlap (153.6–158.8 vs 152.5–156.6), so treat the gap as small. On individual benchmarks: GPQA Diamond — Grok 4.5 93.4%, Gemini 3.5 Flash 92.8%, Claude Sonnet 5 90.5%; FrontierMath Tiers 1–3 — Claude Sonnet 5 65.6%, Gemini 3.5 Flash 62.8%, Grok 4.5 57.2%; OTIS Mock AIME 2024–2025 — Grok 4.5 97.8%, Gemini 3.5 Flash 95.6%, Claude Sonnet 5 94.7%; SimpleQA Verified — Gemini 3.5 Flash 66.2%, Grok 4.5 48.3%, Claude Sonnet 5 33.7%.
Which is better for coding?
There are no published SWE-bench Verified results for Grok 4.5 and Claude Sonnet 5 yet, so there is no like-for-like coding score. On overall capability, Claude Sonnet 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?
Gemini 3.5 Flash has the largest context window at 1,048,576 tokens, against 1,000,000 for Claude Sonnet 5 and 500,000 for Grok 4.5. Maximum output per response: Gemini 3.5 Flash up to 65,536, Grok 4.5 up to 500,000, Claude Sonnet 5 up to 128,000 tokens.
Which can read images, PDFs, audio or video?
Gemini 3.5 Flash accepts text, images, PDFs, audio and video; Grok 4.5 accepts text and images; Claude Sonnet 5 accepts text, images and PDFs. Gemini 3.5 Flash handles the widest range of inputs.
Are any of these open source?
No. Gemini 3.5 Flash, Grok 4.5 and Claude Sonnet 5 are proprietary and only available through APIs and apps.
Which is newer?
Grok 4.5 is the newest, released Jul 8, 2026. Claude Sonnet 5 came out Jun 30, 2026; Gemini 3.5 Flash came out May 19, 2026. Knowledge cutoff: Gemini 3.5 Flash Jan 2025, Claude Sonnet 5 Jan 31, 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.
Related comparisons
- Gemini 3.5 Flash vs Qwen3.7 MaxAlibaba (Qwen) · ECI 153.7
- Gemini 3.5 Flash vs Muse Spark 1.1Meta · ECI 154.3
- Grok 4.5 vs Qwen3.8 Max 0902Alibaba (Qwen) · ECI 155.2
- Grok 4.5 vs Muse Spark 1.1Meta · ECI 154.3
- Claude Sonnet 5 vs Qwen3.8 MaxAlibaba (Qwen) · ECI 156.6
- Claude Sonnet 5 vs Grok 4.6xAI · ECI 156.6
