Gemini 3 Flash Preview vs GLM-5.1
Gemini 3 Flash Preview (2025) and GLM-5.1 (2026) are frontier reasoning models from Google DeepMind and Zhipu AI. Gemini 3 Flash Preview ships a 1m-token context window, while GLM-5.1 ships a 200k-token context window. On pricing, Gemini 3 Flash Preview costs $0.50/1M input tokens versus $0.98/1M for the alternative. 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 Preview is ~96% cheaper at $0.50/1M; pay for GLM-5.1 only for coding workflow support.
Decision scorecard
Local evidence first| Signal | Gemini 3 Flash Preview | 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 | 3 tracked | 5 tracked |
| Shared benchmarks | 0 rows | 0 rows |
Decision tradeoffs
- Gemini 3 Flash Preview has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Gemini 3 Flash Preview has the lower cheapest tracked output price at $3/1M tokens.
- Gemini 3 Flash Preview uniquely exposes Vision and Multimodal in local model data.
- Local decision data tags Gemini 3 Flash Preview for Coding, RAG, and Agents.
- GLM-5.1 has broader tracked provider coverage for fallback and procurement flexibility.
- GLM-5.1 uniquely exposes Reasoning 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 Preview
$1,150
Cheapest tracked route/tier: GCP Vertex AI
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 OpenRouter; 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 in local capability data.
- Provider overlap exists on OpenRouter; start route-level A/B tests there.
- Gemini 3 Flash Preview is $0.08/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Reasoning before moving production traffic.
- Gemini 3 Flash Preview 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 Preview | GLM-5.1 |
|---|---|---|
| Input price | $0.50/1M tokens | $0.98/1M tokens |
| Output price | $3/1M tokens | $3.08/1M tokens |
| Providers |
Capabilities
| Capability | Gemini 3 Flash Preview | GLM-5.1 |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | No |
| Reasoning | No | Yes |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | Yes | Yes |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on vision: Gemini 3 Flash Preview, multimodal input: Gemini 3 Flash Preview, 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 3 Flash Preview lists $0.50/1M input and $3/1M output tokens on the cheapest tracked provider, 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 Preview lower by about $0.36 per million blended tokens. Availability is 3 providers versus 5, so concentration risk also matters.
Choose Gemini 3 Flash Preview when coding workflow support, larger context windows, and lower 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. This keeps the decision grounded in measurable tradeoffs instead of brand-level assumptions.
FAQ
Which has a larger context window, Gemini 3 Flash Preview or GLM-5.1?
Gemini 3 Flash Preview 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 Preview or GLM-5.1?
Gemini 3 Flash Preview is cheaper on tracked token pricing. Gemini 3 Flash Preview costs $0.50/1M input and $3/1M output tokens. GLM-5.1 costs $0.98/1M input and $3.08/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Gemini 3 Flash Preview or GLM-5.1 open source?
Gemini 3 Flash Preview 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 Preview or GLM-5.1?
Gemini 3 Flash Preview 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 Preview or GLM-5.1?
Gemini 3 Flash Preview 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 Preview and GLM-5.1?
Gemini 3 Flash Preview is available on GCP Vertex AI, OpenRouter, and Google AI Studio. 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.
Continue comparing
Last reviewed: 2026-05-25. Data sourced from public model cards and provider documentation.