GLM-5 vs gpt-oss-20b
GLM-5 (2026) and gpt-oss-20b (2025) are frontier reasoning models from Zhipu AI and OpenAI. GLM-5 ships a 200k-token context window, while gpt-oss-20b ships a 131k-token context window. On pricing, gpt-oss-20b costs $0.03/1M input tokens versus $0.60/1M 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.
gpt-oss-20b is ~1900% cheaper at $0.03/1M; pay for GLM-5 only for reasoning depth.
Decision scorecard
Local evidence first| Signal | GLM-5 | gpt-oss-20b |
|---|---|---|
| Best for | reasoning-heavy apps, tool-calling agents, and provider-routed production | tool-calling agents and provider-routed production |
| Decision fit | Coding, RAG, and Agents | RAG, Agents, and Long context |
| Context window | 200k | 131k |
| Cheapest output | $2.08/1M tokens | $0.14/1M tokens |
| Provider routes | 7 tracked | 9 tracked |
| Shared benchmarks | 0 rows | 0 rows |
Decision tradeoffs
- GLM-5 has the larger context window for long prompts, retrieval packs, or transcript analysis.
- GLM-5 uniquely exposes Reasoning in local model data.
- Local decision data tags GLM-5 for Coding, RAG, and Agents.
- gpt-oss-20b has the lower cheapest tracked output price at $0.14/1M tokens.
- gpt-oss-20b has broader tracked provider coverage for fallback and procurement flexibility.
- Local decision data tags gpt-oss-20b for RAG, Agents, and Long context.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
GLM-5
$1,000
Cheapest tracked route/tier: OpenRouter
gpt-oss-20b
$59.00
Cheapest tracked route/tier: OpenRouter
Estimated monthly gap: $941. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on OpenRouter, Fireworks AI, and GCP Vertex AI; start route-level A/B tests there.
- gpt-oss-20b is $1.94/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Reasoning before moving production traffic.
- Provider overlap exists on Fireworks AI, OpenRouter, and GCP Vertex AI; start route-level A/B tests there.
- GLM-5 is $1.94/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- GLM-5 adds Reasoning in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-02-11 | 2025-08-05 |
| Context window | 200k | 131k |
| Parameters | 744B total, 40B active | 20B |
| Architecture | mixture of experts | decoder only |
| License | MIT | Open Source |
| Knowledge cutoff | 2025-11 | 2025-08 |
Pricing and availability
| Pricing attribute | GLM-5 | gpt-oss-20b |
|---|---|---|
| Input price | $0.60/1M tokens | $0.03/1M tokens |
| Output price | $2.08/1M tokens | $0.14/1M tokens |
| Providers |
Capabilities
| Capability | GLM-5 | gpt-oss-20b |
|---|---|---|
| Vision | No | No |
| Multimodal | No | No |
| Reasoning | Yes | No |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | No | No |
| 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 reasoning mode: GLM-5. Both models share function calling, tool use, and structured outputs, 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 lists $0.60/1M input and $2.08/1M output tokens on the cheapest tracked provider, while gpt-oss-20b lists $0.03/1M input and $0.14/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts gpt-oss-20b lower by about $0.98 per million blended tokens. Availability is 7 providers versus 9, so concentration risk also matters.
Choose GLM-5 when reasoning depth and larger context windows are central to the workload. Choose gpt-oss-20b when provider fit, lower input-token cost, 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. It also helps separate model capability from provider packaging, which can change cost and latency. For teams standardizing a stack, that distinction is often the difference between a benchmark win and a reliable deployment.
FAQ
Which has a larger context window, GLM-5 or gpt-oss-20b?
GLM-5 supports 200k tokens, while gpt-oss-20b supports 131k tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is cheaper, GLM-5 or gpt-oss-20b?
gpt-oss-20b is cheaper on tracked token pricing. GLM-5 costs $0.60/1M input and $2.08/1M output tokens. gpt-oss-20b costs $0.03/1M input and $0.14/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is GLM-5 or gpt-oss-20b open source?
GLM-5 is listed under MIT. gpt-oss-20b is listed under Open Source. 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 or gpt-oss-20b?
GLM-5 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 or gpt-oss-20b?
Both GLM-5 and gpt-oss-20b expose function calling. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Where can I run GLM-5 and gpt-oss-20b?
GLM-5 is available on Fireworks AI, OpenRouter, Together AI, GCP Vertex AI, and NVIDIA NIM. gpt-oss-20b is available on Cloudflare Workers AI, OpenRouter, Fireworks AI, GCP Vertex AI, and NVIDIA NIM. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-05-22. Data sourced from public model cards and provider documentation.