o3 vs Claude Sonnet 3.5 v2 vs Gemini 2.5 Pro
Gemini 2.5 Pro comes out ahead, 63 to 58 and 44 on our weighted score, and it is the cheaper option too.
OpenAIo3
58/100- ECI146.9
- Price$2.00 / $8.00
- Context200K
AnthropicClaude Sonnet 3.5 v2
44/100- ECI133.5
- Price$3.00 / $15.00
- Context200K
- Our pick
GoogleGemini 2.5 Pro
63/100- ECI145.3
- Price$1.25 / $10.00
- Context1.05M
Gemini 2.5 Pro is our pick
Gemini 2.5 Pro is the better all-round choice, scoring 63/100 against o3 (58) and Claude Sonnet 3.5 v2 (44). It leads on inputs & features and context window. o3 wins on capability. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
- Capabilityo3Capabilities Index (ECI): o3 146.9 · Gemini 2.5 Pro 145.3 · Claude Sonnet 3.5 v2 133.5
- Lowest priceGemini 2.5 ProGemini 2.5 Pro $3.44 · o3 $3.50 · Claude Sonnet 3.5 v2 $6.00 per 1M tokens (3:1 blend)
- Longest contextGemini 2.5 ProGemini 2.5 Pro 1,048,576 · o3 200,000 · Claude Sonnet 3.5 v2 200,000 tokens
- Widest inputsGemini 2.5 Proo3: Text, Images, PDFs · Claude Sonnet 3.5 v2: Text, Images, PDFs · Gemini 2.5 Pro: Text, Images, PDFs, Audio, Video
- Self-hostingNo open weightsAll three are available only through APIs
| Measure | Weight | o3 | Claude Sonnet 3.5 v2 | Gemini 2.5 Pro |
|---|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 74 | 57 | 72 |
| Price | 25% | 24 | 13 | 24 |
| Inputs & features | 15% | 80 | 60 | 100 |
| Context window | 10% | 32 | 32 | 61 |
| Overall | 100% | 58/100 | 44/100 | 63/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | o3OpenAI | Claude Sonnet 3.5 v2Anthropic | Gemini 2.5 ProGoogle |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 146.9 (best) | 133.5 | 145.3 |
| ECI rank | #63 of 148 (best) | #119 of 148 | #78 of 148 |
| GPQA DiamondGraduate-level science questions | 81.8% | 55.3% | 85.3% (best) |
| FrontierMath Tiers 1–3Research-level mathematics | 33.3% (best) | — | 24.6% |
| OTIS Mock AIME 2024–2025Competition mathematics | 84.4% | 8.5% | 84.7% (best) |
| SWE-bench VerifiedFixing real GitHub issues | 62.3% (best) | — | 57.6% |
| SimpleQA VerifiedShort factual questions | 49.4% | — | — |
| Price per million tokens | |||
| Input | $2.00 | $3.00 | $1.25 (best) |
| Output | $8.00 (best) | $15.00 | $10.00 |
| Cached input | $0.50 | — | $0.125 (best) |
| Blended (3:1) | $3.50 | $6.00 | $3.44 (best) |
| Long-context rate | Same rate | Same rate | Over 200K: $2.50 / $15.00 |
| Price source | Official OpenAI API | Median of 1 providers | Official Google API |
| Limits | |||
| Context window | 200,000 tokens | 200,000 tokens | 1,048,576 tokens (best) |
| Max output | 100,000 tokens (best) | 8,192 tokens | 65,536 tokens |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | Yes | Yes | Yes |
| Audio | No | No | Yes |
| Video | No | No | Yes |
| Reasoning | Yeslow · medium · high | No | Yes |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | No | Yes |
| Availability | |||
| Weights | Proprietary | Proprietary | Proprietary |
| API model ID | o3 | — | gemini-2.5-pro |
| API providers | 18 | 1 | 22 (best) |
| Released | Apr 16, 2025 | Oct 22, 2024 | Jun 17, 2025 |
| Knowledge cutoff | May 2024 | Apr 30, 2024 | Jan 2025 |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- o3$36.00
- Claude Sonnet 3.5 v2$60.00
- Gemini 2.5 Pro$32.50
Which should you choose?
Which is better: o3, Claude Sonnet 3.5 v2 or Gemini 2.5 Pro?
Gemini 2.5 Pro is the better all-round choice, scoring 63/100 against o3 (58) and Claude Sonnet 3.5 v2 (44). It leads on inputs & features and context window. o3 wins on capability. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, o3, Claude Sonnet 3.5 v2 or Gemini 2.5 Pro?
Gemini 2.5 Pro is cheaper at $1.25 input / $10.00 output per million tokens (official Google API price). o3 costs $2.00 input / $8.00 output per million tokens (official OpenAI 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 $3.44 per million tokens for Gemini 2.5 Pro versus $3.50 for o3 (1× as much) and $6.00 for Claude Sonnet 3.5 v2 (1.7× as much).
Which scores higher on benchmarks?
o3 scores higher on the Capabilities Index (ECI): o3 146.9 (#63 of 148), Gemini 2.5 Pro 145.3 (#78 of 148) and Claude Sonnet 3.5 v2 133.5 (#119 of 148). The confidence ranges of the top two overlap (144.9–148.6 vs 143.6–146.9), so treat the gap as small. On individual benchmarks: GPQA Diamond — Gemini 2.5 Pro 85.3%, o3 81.8%, Claude Sonnet 3.5 v2 55.3%; OTIS Mock AIME 2024–2025 — Gemini 2.5 Pro 84.7%, o3 84.4%, Claude Sonnet 3.5 v2 8.5%.
Which is better for coding?
There are no published SWE-bench Verified results for Claude Sonnet 3.5 v2 yet, so there is no like-for-like coding score. On overall capability, o3 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 Pro has the largest context window at 1,048,576 tokens, against 200,000 for o3 and 200,000 for Claude Sonnet 3.5 v2. Maximum output per response: o3 up to 100,000, Claude Sonnet 3.5 v2 up to 8,192, Gemini 2.5 Pro up to 65,536 tokens.
Which can read images, PDFs, audio or video?
o3 accepts text, images and PDFs; Claude Sonnet 3.5 v2 accepts text, images and PDFs; Gemini 2.5 Pro accepts text, images, PDFs, audio and video. Gemini 2.5 Pro handles the widest range of inputs.
Are any of these open source?
No. o3, Claude Sonnet 3.5 v2 and Gemini 2.5 Pro are proprietary and only available through APIs and apps.
Which is newer?
Gemini 2.5 Pro is the newest, released Jun 17, 2025. o3 came out Apr 16, 2025; Claude Sonnet 3.5 v2 came out Oct 22, 2024. Knowledge cutoff: o3 May 2024, Claude Sonnet 3.5 v2 Apr 30, 2024, Gemini 2.5 Pro Jan 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 Oct 4, 2026.
