GLM-5.1 vs Phi-3 Mini 4k
GLM-5.1 (2026) and Phi-3 Mini 4k (2024) are frontier reasoning models from Zhipu AI and Microsoft Research. GLM-5.1 ships a 200k-token context window, while Phi-3 Mini 4k ships a 4k-token context window. On Google-Proof Q&A, GLM-5.1 leads by 45.3 pts. On pricing, Phi-3 Mini 4k costs $0.05/1M 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.
Phi-3 Mini 4k is ~1860% cheaper at $0.05/1M; pay for GLM-5.1 only for coding workflow support.
Decision scorecard
Local evidence first| Signal | GLM-5.1 | Phi-3 Mini 4k |
|---|---|---|
| Best for | reasoning-heavy apps, tool-calling agents, and provider-routed production | provider-routed production |
| Decision fit | Coding, RAG, and Agents | Coding and Classification |
| Context window | 200k | 4k |
| Cheapest output | $3.08/1M tokens | $0.25/1M tokens |
| Provider routes | 5 tracked | 4 tracked |
| Shared benchmarks | Google-Proof Q&A leader | 1 rows |
Decision tradeoffs
- GLM-5.1 holds a shared-benchmark lead on Google-Proof Q&A, ahead by 45.3 points.
- GLM-5.1 has the larger context window for long prompts, retrieval packs, or transcript analysis.
- GLM-5.1 has broader tracked provider coverage for fallback and procurement flexibility.
- GLM-5.1 uniquely exposes Reasoning, Function calling, and Tool use in local model data.
- Local decision data tags GLM-5.1 for Coding, RAG, and Agents.
- Phi-3 Mini 4k has the lower cheapest tracked output price at $0.25/1M tokens.
- Local decision data tags Phi-3 Mini 4k for Coding and Classification.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
GLM-5.1
$1,554
Cheapest tracked route/tier: Z.ai
Phi-3 Mini 4k
$103
Cheapest tracked route/tier: Replicate API
Estimated monthly gap: $1,452. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- No overlapping tracked provider route is sourced for GLM-5.1 and Phi-3 Mini 4k; plan for SDK, billing, or endpoint changes.
- Phi-3 Mini 4k is $2.83/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Reasoning, Function calling, and Tool use before moving production traffic.
- No overlapping tracked provider route is sourced for Phi-3 Mini 4k and GLM-5.1; plan for SDK, billing, or endpoint changes.
- GLM-5.1 is $2.83/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- GLM-5.1 adds Reasoning, Function calling, and Tool use in local capability data.
Specs
Pricing and availability
| Pricing attribute | GLM-5.1 | Phi-3 Mini 4k |
|---|---|---|
| Input price | $0.98/1M tokens | $0.05/1M tokens |
| Output price | $3.08/1M tokens | $0.25/1M tokens |
| Providers |
Capabilities
| Capability | GLM-5.1 | Phi-3 Mini 4k |
|---|---|---|
| Vision | No | No |
| Multimodal | No | No |
| Reasoning | Yes | No |
| Function calling | Yes | No |
| Tool use | Yes | No |
| Structured outputs | Yes | No |
| Code execution | Yes | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
| Benchmark | GLM-5.1 | Phi-3 Mini 4k |
|---|---|---|
| Google-Proof Q&A | 86.2 | 40.9 |
Deep dive
On shared benchmark coverage, Google-Proof Q&A has GLM-5.1 at 86.2 and Phi-3 Mini 4k at 40.9, with GLM-5.1 ahead by 45.3 points. The largest visible gap is 45.3 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 reasoning mode: GLM-5.1, function calling: GLM-5.1, tool use: GLM-5.1, structured outputs: GLM-5.1, and code execution: GLM-5.1. Both models share the core language-model surface, 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, GLM-5.1 lists $0.98/1M input and $3.08/1M output tokens on the cheapest tracked provider, while Phi-3 Mini 4k lists $0.05/1M input and $0.25/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Phi-3 Mini 4k lower by about $1.50 per million blended tokens. Availability is 5 providers versus 4, so concentration risk also matters.
Choose GLM-5.1 when coding workflow support, larger context windows, and broader provider choice are central to the workload. Choose Phi-3 Mini 4k when provider fit 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, GLM-5.1 or Phi-3 Mini 4k?
GLM-5.1 supports 200k tokens, while Phi-3 Mini 4k supports 4k tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, GLM-5.1 or Phi-3 Mini 4k?
Phi-3 Mini 4k is cheaper on tracked token pricing. GLM-5.1 costs $0.98/1M input and $3.08/1M output tokens. Phi-3 Mini 4k costs $0.05/1M input and $0.25/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is GLM-5.1 or Phi-3 Mini 4k open source?
GLM-5.1 is listed under MIT. Phi-3 Mini 4k 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 reasoning mode, GLM-5.1 or Phi-3 Mini 4k?
GLM-5.1 has the clearer documented reasoning mode signal in this comparison. If reasoning mode is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for function calling, GLM-5.1 or Phi-3 Mini 4k?
GLM-5.1 has the clearer documented function calling signal in this comparison. If function calling is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run GLM-5.1 and Phi-3 Mini 4k?
GLM-5.1 is available on Z.ai, OpenRouter, Fireworks AI, Vercel AI Gateway, and Novita AI. Phi-3 Mini 4k is available on Microsoft Foundry, NVIDIA NIM, Baseten API, and Replicate API. 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.