o3 vs Grok 4.3 vs Gemini 2.5 Pro
Grok 4.3 comes out ahead, 67 to 63 and 58 on our weighted score, and it is the cheaper option too.
OpenAIo3
58/100- ECI146.9
- Price$2.00 / $8.00
- Context200K
- Our pick
xAIGrok 4.3
67/100- ECI149.2
- Price$1.25 / $2.50
- Context1M
GoogleGemini 2.5 Pro
63/100- ECI145.3
- Price$1.25 / $10.00
- Context1.05M
Grok 4.3 is our pick
Grok 4.3 is the better all-round choice, scoring 67/100 against Gemini 2.5 Pro (63) and o3 (58). It leads on capability and price. Gemini 2.5 Pro wins on inputs & features. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
- CapabilityGrok 4.3Capabilities Index (ECI): Grok 4.3 149.2 · o3 146.9 · Gemini 2.5 Pro 145.3
- Lowest priceGrok 4.3Grok 4.3 $1.56 · Gemini 2.5 Pro $3.44 · o3 $3.50 per 1M tokens (3:1 blend)
- Longest contextGemini 2.5 ProGemini 2.5 Pro 1,048,576 · Grok 4.3 1,000,000 · o3 200,000 tokens
- Widest inputsGemini 2.5 Proo3: Text, Images, PDFs · Grok 4.3: 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 | Grok 4.3 | Gemini 2.5 Pro |
|---|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 74 | 77 | 72 |
| Price | 25% | 24 | 41 | 24 |
| Inputs & features | 15% | 80 | 80 | 100 |
| Context window | 10% | 32 | 60 | 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 | Grok 4.3xAI | Gemini 2.5 ProGoogle |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 146.9 | 149.2 (best) | 145.3 |
| ECI rank | #63 of 148 | #55 of 148 (best) | #78 of 148 |
| GPQA DiamondGraduate-level science questions | 81.8% | 88.8% (best) | 85.3% |
| FrontierMath Tiers 1–3Research-level mathematics | 33.3% | 42.8% (best) | 24.6% |
| OTIS Mock AIME 2024–2025Competition mathematics | 84.4% | 93.3% (best) | 84.7% |
| SWE-bench VerifiedFixing real GitHub issues | 62.3% (best) | — | 57.6% |
| SimpleQA VerifiedShort factual questions | 49.4% (best) | 33.2% | — |
| Price per million tokens | |||
| Input | $2.00 | $1.25 (best) | $1.25 (best) |
| Output | $8.00 | $2.50 (best) | $10.00 |
| Cached input | $0.50 | $0.20 | $0.125 (best) |
| Blended (3:1) | $3.50 | $1.56 (best) | $3.44 |
| Long-context rate | Same rate | Over 200K: $2.50 / $5.00 | Over 200K: $2.50 / $15.00 |
| Price source | Official OpenAI API | Official xAI API | Official Google API |
| Limits | |||
| Context window | 200,000 tokens | 1,000,000 tokens | 1,048,576 tokens (best) |
| Max output | 100,000 tokens (best) | 30,000 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 | Yeslow · medium · high | Yes |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | Yes | Yes |
| Availability | |||
| Weights | Proprietary | Proprietary | Proprietary |
| API model ID | o3 | grok-4.3 | gemini-2.5-pro |
| API providers | 18 | 27 (best) | 22 |
| Released | Apr 16, 2025 | Apr 17, 2026 | Jun 17, 2025 |
| Knowledge cutoff | May 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
- Grok 4.3$17.50
- Gemini 2.5 Pro$32.50
Which should you choose?
Which is better: o3, Grok 4.3 or Gemini 2.5 Pro?
Grok 4.3 is the better all-round choice, scoring 67/100 against Gemini 2.5 Pro (63) and o3 (58). It leads on capability and price. Gemini 2.5 Pro wins on inputs & features. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, o3, Grok 4.3 or Gemini 2.5 Pro?
Grok 4.3 is cheaper at $1.25 input / $2.50 output per million tokens (official xAI API price). Gemini 2.5 Pro costs $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). At a typical mix of three input tokens to one output token, that is $1.56 per million tokens for Grok 4.3 versus $3.44 for Gemini 2.5 Pro (2.2× as much) and $3.50 for o3 (2.2× as much).
Which scores higher on benchmarks?
Grok 4.3 scores higher on the Capabilities Index (ECI): Grok 4.3 149.2 (#55 of 148), o3 146.9 (#63 of 148) and Gemini 2.5 Pro 145.3 (#78 of 148). The confidence ranges of the top two overlap (147.6–150.8 vs 144.9–148.6), so treat the gap as small. On individual benchmarks: GPQA Diamond — Grok 4.3 88.8%, Gemini 2.5 Pro 85.3%, o3 81.8%; FrontierMath Tiers 1–3 — Grok 4.3 42.8%, o3 33.3%, Gemini 2.5 Pro 24.6%; OTIS Mock AIME 2024–2025 — Grok 4.3 93.3%, Gemini 2.5 Pro 84.7%, o3 84.4%.
Which is better for coding?
There are no published SWE-bench Verified results for Grok 4.3 yet, so there is no like-for-like coding score. On overall capability, Grok 4.3 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 1,000,000 for Grok 4.3 and 200,000 for o3. Maximum output per response: o3 up to 100,000, Grok 4.3 up to 30,000, Gemini 2.5 Pro up to 65,536 tokens.
Which can read images, PDFs, audio or video?
o3 accepts text, images and PDFs; Grok 4.3 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, Grok 4.3 and Gemini 2.5 Pro are proprietary and only available through APIs and apps.
Which is newer?
Grok 4.3 is the newest, released Apr 17, 2026. Gemini 2.5 Pro came out Jun 17, 2025; o3 came out Apr 16, 2025. Knowledge cutoff: o3 May 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.
