Gemini 2.5 Pro vs GLM-5.1
Gemini 2.5 Pro (2025) and GLM-5.1 (2026) are frontier reasoning models from Google DeepMind and Zhipu AI. Gemini 2.5 Pro ships a 1M-token context window, while GLM-5.1 ships a 200k-token context window. On Google-Proof Q&A, GLM-5.1 leads by a hair. On pricing, GLM-5.1 costs $0.95/1M input tokens versus $1.25/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit.
Gemini 2.5 Pro fits 5x more tokens; pick it for long-context work and GLM-5.1 for tighter calls.
Specs
| Released | 2025-06-17 | 2026-03-27 |
| Context window | 1M | 200k |
| Parameters | — | 744B total, 40-44B active |
| Architecture | decoder only | mixture of experts |
| License | Proprietary | Proprietary |
| Knowledge cutoff | 2025-01 | - |
Pricing and availability
| Gemini 2.5 Pro | GLM-5.1 | |
|---|---|---|
| Input price | $1.25/1M tokens | $0.95/1M tokens |
| Output price | $10/1M tokens | $3.15/1M tokens |
| Providers |
Capabilities
| Gemini 2.5 Pro | GLM-5.1 | |
|---|---|---|
| Vision | ||
| Multimodal | ||
| Reasoning | ||
| Function calling | ||
| Tool use | ||
| Structured outputs | ||
| Code execution |
Benchmarks
| Benchmark | Gemini 2.5 Pro | GLM-5.1 |
|---|---|---|
| Google-Proof Q&A | 86.4 | 86.8 |
Deep dive
On shared benchmark coverage, Google-Proof Q&A has Gemini 2.5 Pro at 86.4 and GLM-5.1 at 86.8, with GLM-5.1 ahead by 0.4 points. The largest visible gap is 0.4 points on Google-Proof Q&A, which matters most when that benchmark mirrors your workload. Treat isolated benchmark wins as directional, because provider routing, prompt style, and tool access can move real application results.
The capability footprint differs most on vision: Gemini 2.5 Pro, multimodal input: Gemini 2.5 Pro, and reasoning mode: GLM-5.1. Both models share function calling, tool use, structured outputs, and code execution, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
For cost, Gemini 2.5 Pro lists $1.25/1M input and $10/1M output tokens, while GLM-5.1 lists $0.95/1M input and $3.15/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts GLM-5.1 lower by about $2.27 per million blended tokens. Availability is 3 providers versus 2, so concentration risk also matters.
Choose Gemini 2.5 Pro when coding workflow support, larger context windows, and broader provider choice are central to the workload. Choose GLM-5.1 when coding workflow support and lower input-token cost are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which has a larger context window, Gemini 2.5 Pro or GLM-5.1?
Gemini 2.5 Pro supports 1M tokens, while GLM-5.1 supports 200k tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Gemini 2.5 Pro or GLM-5.1?
GLM-5.1 is cheaper on tracked token pricing. Gemini 2.5 Pro costs $1.25/1M input and $10/1M output tokens. GLM-5.1 costs $0.95/1M input and $3.15/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Gemini 2.5 Pro or GLM-5.1 open source?
Gemini 2.5 Pro is listed under Proprietary. GLM-5.1 is listed under Proprietary. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, Gemini 2.5 Pro or GLM-5.1?
Gemini 2.5 Pro has the clearer documented vision signal in this comparison. If vision is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for multimodal input, Gemini 2.5 Pro or GLM-5.1?
Gemini 2.5 Pro has the clearer documented multimodal input signal in this comparison. If multimodal input is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run Gemini 2.5 Pro and GLM-5.1?
Gemini 2.5 Pro is available on Google AI Studio, GCP Vertex AI, and OpenRouter. GLM-5.1 is available on Z.ai and OpenRouter. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-04-24. Data sourced from public model cards and provider documentation.