Gemini 3 Flash vs GLM-5.1
Gemini 3 Flash (2025) and GLM-5.1 (2026) are frontier reasoning models from Google DeepMind and Zhipu AI. Gemini 3 Flash ships a 1m-token context window, while GLM-5.1 ships a 200k-token context window. On Google-Proof Q&A, Gemini 3 Flash leads by 4.2 pts. On pricing, Gemini 3 Flash costs $0.50/1M input tokens; GLM-5.1 costs $0.98/1M input tokens. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
Gemini 3 Flash fits 5x more tokens; pick it for long-context work and GLM-5.1 for tighter calls.
Decision scorecard
Local evidence first| Signal | Gemini 3 Flash | GLM-5.1 |
|---|---|---|
| Best for | multimodal apps, tool-calling agents, and long-context analysis | reasoning-heavy apps, tool-calling agents, and provider-routed production |
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 1m | 200k |
| Cheapest output | $3/1M tokens | $3.08/1M tokens |
| Provider routes | 4 tracked | 5 tracked |
| Shared benchmarks | Google-Proof Q&A leader | 2 rows |
Decision tradeoffs
- Gemini 3 Flash leads the largest shared benchmark signal on Google-Proof Q&A by 4.2 points.
- Gemini 3 Flash has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Gemini 3 Flash has the lower cheapest tracked output price at $3/1M tokens.
- Gemini 3 Flash uniquely exposes Vision and Multimodal in local model data.
- Local decision data tags Gemini 3 Flash for Coding, RAG, and Agents.
- GLM-5.1 leads the largest shared benchmark signal on Chatbot Arena by 5 points.
- GLM-5.1 has broader tracked provider coverage for fallback and procurement flexibility.
- GLM-5.1 uniquely exposes Reasoning and Structured outputs in local model data.
- Local decision data tags GLM-5.1 for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Gemini 3 Flash
$1,150
Cheapest tracked route/tier: Replicate API
GLM-5.1
$1,554
Cheapest tracked route/tier: Z.ai
Estimated monthly gap: $404. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on Vercel AI Gateway; start route-level A/B tests there.
- GLM-5.1 is $0.08/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Check replacement coverage for Vision and Multimodal before moving production traffic.
- GLM-5.1 adds Reasoning and Structured outputs in local capability data.
- Provider overlap exists on Vercel AI Gateway; start route-level A/B tests there.
- Gemini 3 Flash is $0.08/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Reasoning and Structured outputs before moving production traffic.
- Gemini 3 Flash adds Vision and Multimodal in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-12-17 | 2026-04-07 |
| Context window | 1m | 200k |
| Parameters | — | 754B total, 40B active |
| Architecture | decoder only | mixture of experts |
| License | Proprietary | MIT |
| Knowledge cutoff | 2025-01 | 2025-11 |
Pricing and availability
| Pricing attribute | Gemini 3 Flash | GLM-5.1 |
|---|---|---|
| Input price |
| $0.98/1M tokens |
| Output price |
| $3.08/1M tokens |
| Providers |
Capabilities
| Capability | Gemini 3 Flash | GLM-5.1 |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | No |
| Reasoning | No | Yes |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | No | Yes |
| Code execution | Yes | Yes |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
| Benchmark | Gemini 3 Flash | GLM-5.1 |
|---|---|---|
| Google-Proof Q&A | 90.4 | 86.2 |
| Chatbot Arena | 1467.0 | 1472.0 |
Deep dive
On shared benchmark coverage, Google-Proof Q&A has Gemini 3 Flash at 90.4 and GLM-5.1 at 86.2, with Gemini 3 Flash ahead by 4.2 points; Chatbot Arena has Gemini 3 Flash at 1467 and GLM-5.1 at 1472, with GLM-5.1 ahead by 5 points. The largest visible gap is 5 points on Chatbot Arena, 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 3 Flash, multimodal input: Gemini 3 Flash, reasoning mode: GLM-5.1, and structured outputs: GLM-5.1. Both models share function calling, tool use, 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 3 Flash lists tiered pricing: 0-200,001t is $0.50/1M input and $3/1M output; 200,001t+ is $0.50/1M input and $3/1M output, while GLM-5.1 lists $0.98/1M input and $3.08/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Gemini 3 Flash lower by about $0.36 per million blended tokens. For tiered rows, this cheapest-track view can understate interactive or fast-lane spend, so compare the tier you will actually use. Availability is 4 providers versus 5, so concentration risk also matters.
Choose Gemini 3 Flash when coding workflow support, larger context windows, and lower cheapest-tier input-token cost are central to the workload. Choose GLM-5.1 when coding workflow support and broader provider choice 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 3 Flash or GLM-5.1?
Gemini 3 Flash 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 3 Flash or GLM-5.1?
Gemini 3 Flash lists tiered pricing: 0-200,001t is $0.50/1M input and $3/1M output; 200,001t+ is $0.50/1M input and $3/1M output. GLM-5.1 lists $0.98/1M input and $3.08/1M output tokens on the cheapest tracked provider. Compare the tier you will actually use; cheap async pricing can overstate savings for interactive workflows. Provider discounts or batch pricing can still change the final bill.
Is Gemini 3 Flash or GLM-5.1 open source?
Gemini 3 Flash is listed under Proprietary. GLM-5.1 is listed under MIT. 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 3 Flash or GLM-5.1?
Gemini 3 Flash 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 3 Flash or GLM-5.1?
Gemini 3 Flash 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 3 Flash and GLM-5.1?
Gemini 3 Flash is available on Replicate API, GCP Vertex AI, Google AI Studio, and Vercel AI Gateway. GLM-5.1 is available on Z.ai, OpenRouter, Fireworks AI, Vercel AI Gateway, and Novita AI. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-05-25. Data sourced from public model cards and provider documentation.