API cost decision in 10 seconds

🔥GLM 5.1 vs 🔥GPT-5.5

Pick GLM 5.1 for lower cost; pick GPT-5.5 only if the larger context window matters more.

Pricing data updated:  Prices normalized to USD per 1M tokens Sample workload: 1M input + 500K output

Budget verdict

Pick GLM 5.1 for lower cost; pick GPT-5.5 only if the larger context window matters more.

On the standard 1M input plus 500K output workload, GLM 5.1 is estimated at $2.52 vs $20 for GPT-5.5, saving $17.48 (87.4% lower).

Cost-first pickGLM 5.1
Context-first pickGPT-5.5
Sample savings$17.4887.4%
10x traffic gap$174.8

GPT-5.5 has more context, but GLM 5.1 saves $17.48 on the standard workload. At 10x that traffic, the same price gap is about $174.8. Use the calculator below to replace the sample workload with your own token volume.

Cheaper input GLM 5.1 $0.98 vs $5 / 1M

GLM 5.1 is $4.02 cheaper per 1M input tokens (80.4% lower; 5.1x difference).

Cheaper output GLM 5.1 $3.08 vs $30 / 1M

GLM 5.1 is $26.92 cheaper per 1M output tokens (89.7% lower; 9.74x difference).

Larger context GPT-5.5 202.75K vs 1.05M

GPT-5.5 has 847.25K more context (5.18x larger).

Sample workload GLM 5.1 $2.52 vs $20

GLM 5.1 is $17.48 cheaper on the standard workload (87.4% lower).

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.
GLM 5.1 Calculating… Estimated API cost
GPT-5.5 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

GLM 5.1 has the lower input price; GLM 5.1 has the lower output price; GPT-5.5 offers the larger context window. For the 1M input plus 500K output sample, GLM 5.1 is cheaper for the standard workload.

For a 1M input token plus 500K output token workload, the estimated API cost is $2.52 for GLM 5.1 and $20 for GPT-5.5.

Best Fit

Choose GLM 5.1 when you care most about lower input-token price, and lower output-token price.

Choose GPT-5.5 when you care most about larger context window.

Decision Notes
  • On the standard 1M input plus 500K output workload, GLM 5.1 is estimated at $2.52 vs $20 for GPT-5.5, saving $17.48 (87.4% lower).
  • GLM 5.1 is $17.48 cheaper on the standard workload (87.4% lower).
  • GLM 5.1 is $4.02 cheaper per 1M input tokens (80.4% lower; 5.1x difference).
  • GLM 5.1 is $26.92 cheaper per 1M output tokens (89.7% lower; 9.74x difference).
  • GPT-5.5 has 847.25K more context (5.18x larger).
Head-to-Head Specs
Feature🔥GLM 5.1
(Z.ai)		🔥GPT-5.5
(OpenAI)
Input Price
prompt tokens per 1M		$0.98$5
Completion Price
per 1M tokens		$3.08$30
Sample Workload Cost
1M input + 500K output		$2.52$20
Context Window202.75K1.05M
Release Date
Popularity Rank
current rank		#13#19

Use-Case Decision Matrix

Use caseBetter pickWhy
Budget-constrained productionGLM 5.1On the standard 1M input plus 500K output workload, GLM 5.1 is estimated at $2.52 vs $20 for GPT-5.5, saving $17.48 (87.4% lower).
High-volume input processingGLM 5.1Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill.
Long responses and chatbotsGLM 5.1Lower output-token price matters most when assistants generate many completion tokens.
RAG or long-document workGPT-5.5A 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

Cheaper alternatives

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Larger context alternatives

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Provider catalogs

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Z.ai catalog

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OpenAI catalog

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GLM 5.1

GLM-5.1 delivers a major leap in coding capability, with particularly significant gains in handling long-horizon tasks. Unlike previous models built around minute-level interactions, GLM-5.1 can work independently and continuously on...

GPT-5.5

GPT-5.5 is OpenAI’s frontier model designed for complex professional workloads, building on GPT-5.4 with stronger reasoning, higher reliability, and improved token efficiency on hard tasks. It features a 1M+ token...