o3 vs Gemini 3 Pro Preview vs Gemini 2.5 Pro
Gemini 3 Pro Preview comes out ahead, 67 to 63 and 58 on our weighted score, though Gemini 2.5 Pro is 24% cheaper per token.
OpenAIo3
58/100- ECI146.9
- Price$2.00 / $8.00
- Context200K
- Our pick
GoogleGemini 3 Pro Preview
67/100- ECI153.0
- Price$2.00 / $12.00
- Context1.05M
- Google
Gemini 2.5 Pro
63/100- ECI145.3
- Price$1.25 / $10.00
- Context1.05M
Gemini 3 Pro Preview is our pick
Gemini 3 Pro Preview is the better all-round choice, scoring 67/100 against Gemini 2.5 Pro (63) and o3 (58). It leads on capability. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
- CapabilityGemini 3 Pro PreviewCapabilities Index (ECI): Gemini 3 Pro Preview 153.0 · o3 146.9 · Gemini 2.5 Pro 145.3
- Lowest priceGemini 2.5 ProGemini 2.5 Pro $3.44 · o3 $3.50 · Gemini 3 Pro Preview $4.50 per 1M tokens (3:1 blend)
- Longest contextGemini 3 Pro Preview and Gemini 2.5 ProGemini 3 Pro Preview 1,048,576 · Gemini 2.5 Pro 1,048,576 · o3 200,000 tokens
- Widest inputsGemini 3 Pro Preview and Gemini 2.5 Proo3: Text, Images, PDFs · Gemini 3 Pro Preview: Text, Images, PDFs, Audio, Video · Gemini 2.5 Pro: Text, Images, PDFs, Audio, Video
- Self-hostingNo open weightsAll three are available only through APIs
| Measure | Weight | o3 | Gemini 3 Pro Preview | Gemini 2.5 Pro |
|---|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 74 | 82 | 72 |
| Price | 25% | 24 | 19 | 24 |
| Inputs & features | 15% | 80 | 100 | 100 |
| Context window | 10% | 32 | 61 | 61 |
| Overall | 100% | 58/100 | 67/100 | 63/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | o3OpenAI | Gemini 3 Pro PreviewGoogle | Gemini 2.5 ProGoogle |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 146.9 | 153.0 (best) | 145.3 |
| ECI rank | #63 of 148 | #39 of 148 (best) | #78 of 148 |
| GPQA DiamondGraduate-level science questions | 81.8% | 92.6% (best) | 85.3% |
| FrontierMath Tiers 1–3Research-level mathematics | 33.3% (best) | — | 24.6% |
| OTIS Mock AIME 2024–2025Competition mathematics | 84.4% | 91.4% (best) | 84.7% |
| SWE-bench VerifiedFixing real GitHub issues | 62.3% | 72.9% (best) | 57.6% |
| SimpleQA VerifiedShort factual questions | 49.4% | — | — |
| Price per million tokens | |||
| Input | $2.00 | $2.00 | $1.25 (best) |
| Output | $8.00 (best) | $12.00 | $10.00 |
| Cached input | $0.50 | — | $0.125 (best) |
| Blended (3:1) | $3.50 | $4.50 | $3.44 (best) |
| Long-context rate | Same rate | Same rate | Over 200K: $2.50 / $15.00 |
| Price source | Official OpenAI API | Median of 2 providers | Official Google API |
| Limits | |||
| Context window | 200,000 tokens | 1,048,576 tokens (best) | 1,048,576 tokens (best) |
| Max output | 100,000 tokens (best) | 65,536 tokens | 65,536 tokens |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | Yes | Yes | Yes |
| Audio | No | Yes | Yes |
| Video | No | Yes | Yes |
| Reasoning | Yeslow · medium · high | Yes | Yes |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | Yes | Yes |
| Availability | |||
| Weights | Proprietary | Proprietary | Proprietary |
| API model ID | o3 | — | gemini-2.5-pro |
| API providers | 18 | 3 | 22 (best) |
| Released | Apr 16, 2025 | Nov 18, 2025 | Jun 17, 2025 |
| Knowledge cutoff | May 2024 | Jan 2025 | 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
- Gemini 3 Pro Preview$44.00
- Gemini 2.5 Pro$32.50
Which should you choose?
Which is better: o3, Gemini 3 Pro Preview or Gemini 2.5 Pro?
Gemini 3 Pro Preview is the better all-round choice, scoring 67/100 against Gemini 2.5 Pro (63) and o3 (58). It leads on capability. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, o3, Gemini 3 Pro Preview 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); Gemini 3 Pro Preview costs $2.00 input / $12.00 output per million tokens (median across 2 API providers). 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 $4.50 for Gemini 3 Pro Preview (1.3× as much).
Which scores higher on benchmarks?
Gemini 3 Pro Preview scores higher on the Capabilities Index (ECI): Gemini 3 Pro Preview 153.0 (#39 of 148), o3 146.9 (#63 of 148) and Gemini 2.5 Pro 145.3 (#78 of 148). Their confidence ranges do not overlap (150.6–155.2 vs 144.9–148.6), so the gap is a real one. On individual benchmarks: GPQA Diamond — Gemini 3 Pro Preview 92.6%, Gemini 2.5 Pro 85.3%, o3 81.8%; OTIS Mock AIME 2024–2025 — Gemini 3 Pro Preview 91.4%, Gemini 2.5 Pro 84.7%, o3 84.4%; SWE-bench Verified — Gemini 3 Pro Preview 72.9%, o3 62.3%, Gemini 2.5 Pro 57.6%.
Which is better for coding?
Gemini 3 Pro Preview resolves more real GitHub issues on SWE-bench Verified: Gemini 3 Pro Preview 72.9%, o3 62.3% and Gemini 2.5 Pro 57.6%. All three support tool calling for agent workflows.
Which has the bigger context window?
Gemini 3 Pro Preview and Gemini 2.5 Pro have the largest context windows (1,048,576 and 1,048,576 tokens), against 200,000 for o3. Maximum output per response: o3 up to 100,000, Gemini 3 Pro Preview up to 65,536, Gemini 2.5 Pro up to 65,536 tokens.
Which can read images, PDFs, audio or video?
o3 accepts text, images and PDFs; Gemini 3 Pro Preview accepts text, images, PDFs, audio and video; Gemini 2.5 Pro accepts text, images, PDFs, audio and video. Gemini 3 Pro Preview handles the widest range of inputs.
Are any of these open source?
No. o3, Gemini 3 Pro Preview and Gemini 2.5 Pro are proprietary and only available through APIs and apps.
Which is newer?
Gemini 3 Pro Preview is the newest, released Nov 18, 2025. Gemini 2.5 Pro came out Jun 17, 2025; o3 came out Apr 16, 2025. Knowledge cutoff: o3 May 2024, Gemini 3 Pro Preview Jan 2025, 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.
