API cost decision in 10 seconds

🔥GLM 5.1 vs 🔥Grok 4.1 Fast

Use the price and context table to shortlist the better API fit; one or both models are missing full workload pricing.

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

Budget verdict

Use the price and context table to shortlist the better API fit; one or both models are missing full workload pricing.

The standard workload estimate is unavailable because one or both models are missing numeric input or output prices.

Cost-first pickN/A
Context-first pickGLM 5.1
Sample savingsN/AN/A
10x traffic gapN/A

Context-window winner: GLM 5.1. Use the custom calculator below when both input and output prices are available.

Cheaper input Tie $0.98 vs Not listed / 1M

Input price data is incomplete for one or both models.

Cheaper output Tie $3.08 vs Not listed / 1M

Output price data is incomplete for one or both models.

Larger context GLM 5.1 202.75K vs N/A

Context window data is incomplete for one or both models.

Sample workload N/A $2.52 vs N/A

The standard workload estimate is unavailable because one or both models are missing numeric prices.

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.
GLM 5.1 Calculating… Estimated API cost
Grok 4.1 Fast 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

both models tie on input price; both models tie on output price; GLM 5.1 offers the larger context window. For the 1M input plus 500K output sample, the standard workload cost is unavailable.

For a 1M input token plus 500K output token workload, the estimated API cost is $2.52 for GLM 5.1 and N/A for Grok 4.1 Fast.

Best Fit

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

Choose Grok 4.1 Fast when its provider, model quality, latency, or availability is more important than the numeric price/context winner.

Decision Notes
  • The standard workload estimate is unavailable because one or both models are missing numeric input or output prices.
  • The standard workload estimate is unavailable because one or both models are missing numeric prices.
  • Input price data is incomplete for one or both models.
  • Output price data is incomplete for one or both models.
  • Context window data is incomplete for one or both models.
Head-to-Head Specs
Feature🔥GLM 5.1
(Z.ai)		🔥Grok 4.1 Fast
(x-ai)
Input Price
prompt tokens per 1M		$0.98Not listed
Completion Price
per 1M tokens		$3.08Not listed
Sample Workload Cost
1M input + 500K output		$2.52N/A
Context Window202.75KN/A
Release DateN/A
Popularity Rank
current rank		#13#18

Use-Case Decision Matrix

Use caseBetter pickWhy
Budget-constrained productionN/AThe standard workload estimate is unavailable because one or both models are missing numeric input or output prices.
High-volume input processingTieLower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill.
Long responses and chatbotsTieLower 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
  • Llama 4 Scout offers 10M context with $0.23 sample workload cost.
  • Grok 4.20 Multi-Agent offers 2M context with $5 sample workload cost.
  • Grok 4.20 offers 2M context with $2.5 sample workload cost.
  • GPT-5.5 offers 1.05M context with $20 sample workload cost.

Cheaper alternatives

Review low-cost models ranked by a standard 1M input plus 500K output workload.

Open cheapest models

Larger context alternatives

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

Open largest context models

Provider catalogs

Compare models within provider hubs before choosing a final API vendor.

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Z.ai catalog

Review all tracked Z.ai models before deciding whether this matchup is the right shortlist.

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x-ai catalog

Check other x-ai models with comparable pricing, context, or release timing.

Open x-ai models
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...

Grok 4.1 Fast

This model appears in the model catalog's daily usage rankings, but the models API did not return pricing or context metadata for it.