Gemini 2.5 Pro vs GLM-5.1 vs o3
Gemini 2.5 Pro comes out ahead, 63 to 58 and 57 on our weighted score, though GLM-5.1 is 37% cheaper per token.
- Our pick
GoogleGemini 2.5 Pro
63/100- ECI145.3
- Price$1.25 / $10.00
- Context1.05M
Z.ai (Zhipu)GLM-5.1
57/100- ECI149.9
- Price$1.40 / $4.40
- Context200K
OpenAIo3
58/100- ECI146.9
- Price$2.00 / $8.00
- Context200K
Gemini 2.5 Pro is our pick
Gemini 2.5 Pro is the better all-round choice, scoring 63/100 against o3 (58) and GLM-5.1 (57). It leads on inputs & features and context window. GLM-5.1 wins on capability and price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
- CapabilityGLM-5.1Capabilities Index (ECI): GLM-5.1 149.9 · o3 146.9 · Gemini 2.5 Pro 145.3
- Lowest priceGLM-5.1GLM-5.1 $2.15 · 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 · GLM-5.1 200,000 · o3 200,000 tokens
- Widest inputsGemini 2.5 ProGemini 2.5 Pro: Text, Images, PDFs, Audio, Video · GLM-5.1: Text · o3: Text, Images, PDFs
- Self-hostingGLM-5.1Publishes downloadable weights
| Measure | Weight | Gemini 2.5 Pro | GLM-5.1 | o3 |
|---|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 72 | 78 | 74 |
| Price | 25% | 24 | 34 | 24 |
| Inputs & features | 15% | 100 | 45 | 80 |
| Context window | 10% | 61 | 32 | 32 |
| Overall | 100% | 63/100 | 57/100 | 58/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | Gemini 2.5 ProGoogle | GLM-5.1Z.ai (Zhipu) | o3OpenAI |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 145.3 | 149.9 (best) | 146.9 |
| ECI rank | #78 of 148 | #51 of 148 (best) | #63 of 148 |
| GPQA DiamondGraduate-level science questions | 85.3% | 89.9% (best) | 81.8% |
| FrontierMath Tiers 1–3Research-level mathematics | 24.6% | 36.8% (best) | 33.3% |
| OTIS Mock AIME 2024–2025Competition mathematics | 84.7% | 93.3% (best) | 84.4% |
| SWE-bench VerifiedFixing real GitHub issues | 57.6% | 74.2% (best) | 62.3% |
| SimpleQA VerifiedShort factual questions | — | 34.0% | 49.4% (best) |
| Price per million tokens | |||
| Input | $1.25 (best) | $1.40 | $2.00 |
| Output | $10.00 | $4.40 (best) | $8.00 |
| Cached input | $0.125 (best) | $0.26 | $0.50 |
| Blended (3:1) | $3.44 | $2.15 (best) | $3.50 |
| Long-context rate | Over 200K: $2.50 / $15.00 | Same rate | Same rate |
| Price source | Official Google API | Official Z.AI API | Official OpenAI API |
| Limits | |||
| Context window | 1,048,576 tokens (best) | 200,000 tokens | 200,000 tokens |
| Max output | 65,536 tokens | 131,072 tokens (best) | 100,000 tokens |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | No | Yes |
| PDFs | Yes | No | Yes |
| Audio | Yes | No | No |
| Video | Yes | No | No |
| Reasoning | Yes | Yes | Yeslow · medium · high |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | Yes | Yes |
| Availability | |||
| Weights | Proprietary | Open | Proprietary |
| API model ID | gemini-2.5-pro | glm-5.1 | o3 |
| API providers | 22 | 40 (best) | 18 |
| Released | Jun 17, 2025 | Apr 7, 2026 | Apr 16, 2025 |
| Knowledge cutoff | Jan 2025 | — | May 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 Pro$32.50
- GLM-5.1$22.80
- o3$36.00
Which should you choose?
Which is better: Gemini 2.5 Pro, GLM-5.1 or o3?
Gemini 2.5 Pro is the better all-round choice, scoring 63/100 against o3 (58) and GLM-5.1 (57). It leads on inputs & features and context window. GLM-5.1 wins on capability and price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, Gemini 2.5 Pro, GLM-5.1 or o3?
GLM-5.1 is cheaper at $1.40 input / $4.40 output per million tokens (official Z.AI 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 $2.15 per million tokens for GLM-5.1 versus $3.44 for Gemini 2.5 Pro (1.6× as much) and $3.50 for o3 (1.6× as much).
Which scores higher on benchmarks?
GLM-5.1 scores higher on the Capabilities Index (ECI): GLM-5.1 149.9 (#51 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 (148.0–151.6 vs 144.9–148.6), so treat the gap as small. On individual benchmarks: GPQA Diamond — GLM-5.1 89.9%, Gemini 2.5 Pro 85.3%, o3 81.8%; FrontierMath Tiers 1–3 — GLM-5.1 36.8%, o3 33.3%, Gemini 2.5 Pro 24.6%; OTIS Mock AIME 2024–2025 — GLM-5.1 93.3%, Gemini 2.5 Pro 84.7%, o3 84.4%; SWE-bench Verified — GLM-5.1 74.2%, o3 62.3%, Gemini 2.5 Pro 57.6%.
Which is better for coding?
GLM-5.1 resolves more real GitHub issues on SWE-bench Verified: GLM-5.1 74.2%, 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 2.5 Pro has the largest context window at 1,048,576 tokens, against 200,000 for GLM-5.1 and 200,000 for o3. Maximum output per response: Gemini 2.5 Pro up to 65,536, GLM-5.1 up to 131,072, o3 up to 100,000 tokens.
Which can read images, PDFs, audio or video?
Gemini 2.5 Pro accepts text, images, PDFs, audio and video; GLM-5.1 accepts text; o3 accepts text, images and PDFs. Gemini 2.5 Pro handles the widest range of inputs.
Are any of these open source?
GLM-5.1 publishes its weights and can be self-hosted; Gemini 2.5 Pro and o3 is proprietary.
Which is newer?
GLM-5.1 is the newest, released Apr 7, 2026. Gemini 2.5 Pro came out Jun 17, 2025; o3 came out Apr 16, 2025. Knowledge cutoff: Gemini 2.5 Pro Jan 2025, o3 May 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.
