API cost decision in 10 seconds

GLM 5.1 vs GPT-4o-mini

Pick GPT-4o-mini for lower cost; pick GLM 5.1 only if the larger context window matters more.

Page updated:  Data confirmed:  Prices normalized to USD per 1M tokens Sample workload: 1M input + 500K output

Budget verdict

Pick GPT-4o-mini for lower cost; pick GLM 5.1 only if the larger context window matters more.

On the standard 1M input plus 500K output workload, GPT-4o-mini is estimated at $0.45 vs $2.48 for GLM 5.1, saving $2.03 (81.9% lower).

Cost-first pickGPT-4o-mini
Context-first pickGLM 5.1
Sample savings$2.0381.9%
10x traffic gap$20.34

GLM 5.1 has more context, but GPT-4o-mini saves $2.03 on the standard workload. At 10x that traffic, the same price gap is about $20.34. Use the calculator below to replace the sample workload with your own token volume.

Cost sensitivity

Workload Sensitivity

Same prices, different token mixes.

GPT-4o-mini stays cheaper across input-heavy, balanced, and output-heavy sample workloads.

Workload shapeToken mixBetter pickGLM 5.1GPT-4o-mini
Input-heavy / RAG5M input + 500K outputGPT-4o-mini$6.35$1.05
Balanced workload1M input + 1M outputGPT-4o-mini$4$0.75
Output-heavy chatbot1M input + 5M outputGPT-4o-mini$16.15$3.15
Cheaper input GPT-4o-mini $0.966 vs $0.15 / 1M

GPT-4o-mini is $0.82 cheaper per 1M input tokens (84.5% lower; 6.44x difference).

Cheaper output GPT-4o-mini $3.036 vs $0.6 / 1M

GPT-4o-mini is $2.44 cheaper per 1M output tokens (80.2% lower; 5.06x difference).

Larger context GLM 5.1 204.8K vs 128K

GLM 5.1 has 76.8K more context (1.6x larger).

Sample workload GPT-4o-mini $2.48 vs $0.45

GPT-4o-mini is $2.03 cheaper on the standard workload (81.9% lower).

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.
GLM 5.1 Calculating… Estimated API cost
GPT-4o-mini Calculating… Estimated API cost
Cheaper for this workload Calculating… Difference: calculating…

This estimate uses normalized public API pricing per 1M tokens. It is a planning aid, not a billing quote. Verify provider pricing, limits, and terms before production use.

Quick Decision

Verdict

GPT-4o-mini has the lower input price; GPT-4o-mini has the lower output price; GLM 5.1 offers the larger context window. For the 1M input plus 500K output sample, GPT-4o-mini is cheaper for the standard workload.

For a 1M input token plus 500K output token workload, the estimated API cost is $2.48 for GLM 5.1 and $0.45 for GPT-4o-mini.

Best Fit

Choose GLM 5.1 when you care most about larger context window.

Choose GPT-4o-mini when you care most about lower input-token price, and lower output-token price.

Decision Notes
  • On the standard 1M input plus 500K output workload, GPT-4o-mini is estimated at $0.45 vs $2.48 for GLM 5.1, saving $2.03 (81.9% lower).
  • GPT-4o-mini is $2.03 cheaper on the standard workload (81.9% lower).
  • GPT-4o-mini is $0.82 cheaper per 1M input tokens (84.5% lower; 6.44x difference).
  • GPT-4o-mini is $2.44 cheaper per 1M output tokens (80.2% lower; 5.06x difference).
  • GLM 5.1 has 76.8K more context (1.6x larger).
Head-to-Head Specs
FeatureGLM 5.1
(Z.ai)		GPT-4o-mini
(OpenAI)
Input Price
prompt tokens per 1M		$0.966$0.15
Completion Price
per 1M tokens		$3.036$0.6
Sample Workload Cost
1M input + 500K output		$2.48$0.45
Context Window204.8K128K
Release Date
Popularity#24#26

Use-Case Decision Matrix

Use caseBetter pickWhy
Budget-constrained productionGPT-4o-miniOn the standard 1M input plus 500K output workload, GPT-4o-mini is estimated at $0.45 vs $2.48 for GLM 5.1, saving $2.03 (81.9% lower).
High-volume input processingGPT-4o-miniLower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill.
Long responses and chatbotsGPT-4o-miniLower output-token price matters most when assistants generate many completion tokens.
RAG or long-document workGLM 5.1A larger context window leaves more room for retrieved passages, conversation history, or source files.

Related Alternatives

Same-provider lower-cost swaps
  • GLM 4.5 Air (free) can replace GLM 5.1 when lower sample workload cost matters most: $0.
  • GLM 4 32B can replace GLM 5.1 when lower sample workload cost matters most: $0.15.
  • GLM 4.7 Flash can replace GLM 5.1 when lower sample workload cost matters most: $0.26.
  • GLM 4.5 Air can replace GLM 5.1 when lower sample workload cost matters most: $0.55.
Larger context near this budget
  • Grok 4.20 offers 2M context with $2.5 sample workload cost.
  • Grok 4.20 Multi-Agent offers 2M context with $2.5 sample workload cost.
  • Llama 4 Scout offers 1.31M context with $0.25 sample workload cost.
  • MiMo-V2.5 offers 1.05M context with $0.28 sample workload cost.

Cheaper alternatives

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Larger context alternatives

Find models with larger context windows for RAG, long documents, and codebase review.

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Provider catalogs

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Z.ai catalog

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OpenAI catalog

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