API cost decision in 10 seconds

GLM 5.1 vs GLM 4.6

Pick GLM 4.6 when budget is the priority.

Page updated: 2026-05-26T15:08:08Z Data confirmed: 2026-05-26T19:08:13Z Prices normalized to USD per 1M tokens Sample workload: 1M input + 500K output

Budget verdict

Pick GLM 4.6 when budget is the priority.

On the standard 1M input plus 500K output workload, GLM 4.6 is estimated at $1.3 vs $2.52 for GLM 5.1, saving $1.22 (48.4% lower).

Cost-first pickGLM 4.6

Context-first pickBoth models

Sample savings$1.2248.4%

10x traffic gap$12.2

The reported context window is tied, so cost and provider fit carry more weight. At 10x that traffic, the same price gap is about $12.2. Use the calculator below to replace the sample workload with your own token volume.

Cost sensitivity

Workload Sensitivity

Same prices, different token mixes.

GLM 4.6 stays cheaper across input-heavy, balanced, and output-heavy sample workloads.

Workload shape	Token mix	Better pick	GLM 5.1	GLM 4.6
Input-heavy / RAG	5M input + 500K output	GLM 4.6	$6.44	$3.02
Balanced workload	1M input + 1M output	GLM 4.6	$4.06	$2.17
Output-heavy chatbot	1M input + 5M output	GLM 4.6	$16.38	$9.13

Cheaper input GLM 4.6 $0.98 vs $0.43 / 1M

GLM 4.6 is $0.55 cheaper per 1M input tokens (56.1% lower; 2.28x difference).

Cheaper output GLM 4.6 $3.08 vs $1.74 / 1M

GLM 4.6 is $1.34 cheaper per 1M output tokens (43.5% lower; 1.77x difference).

Larger context Tie 202.75K vs 202.75K

Both models report the same context window at 202.75K tokens.

Sample workload GLM 4.6 $2.52 vs $1.3

GLM 4.6 is $1.22 cheaper on the standard workload (48.4% lower).

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.

Monthly input tokens Monthly output tokens

GLM 5.1 Calculating… Estimated API cost

GLM 4.6 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 4.6 has the lower input price; GLM 4.6 has the lower output price; both models report the same context window. For the 1M input plus 500K output sample, GLM 4.6 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 $1.3 for GLM 4.6.

Best Fit

Choose GLM 5.1 when its provider, model quality, latency, or availability is more important than the numeric price/context winner.

Choose GLM 4.6 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, GLM 4.6 is estimated at $1.3 vs $2.52 for GLM 5.1, saving $1.22 (48.4% lower).
GLM 4.6 is $1.22 cheaper on the standard workload (48.4% lower).
GLM 4.6 is $0.55 cheaper per 1M input tokens (56.1% lower; 2.28x difference).
GLM 4.6 is $1.34 cheaper per 1M output tokens (43.5% lower; 1.77x difference).
Both models report the same context window at 202.75K tokens.

Head-to-Head Specs

Feature	GLM 5.1 (Z.ai)	GLM 4.6 (Z.ai)
Input Price prompt tokens per 1M	$0.98	$0.43
Completion Price per 1M tokens	$3.08	$1.74
Sample Workload Cost 1M input + 500K output	$2.52	$1.3
Context Window	202.75K	202.75K
Release Date	2026-04-07	2025-09-30
Popularity	#23	#63

Use-Case Decision Matrix

Use case	Better pick	Why
Budget-constrained production	GLM 4.6	On the standard 1M input plus 500K output workload, GLM 4.6 is estimated at $1.3 vs $2.52 for GLM 5.1, saving $1.22 (48.4% lower).
High-volume input processing	GLM 4.6	Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill.
Long responses and chatbots	GLM 4.6	Lower output-token price matters most when assistants generate many completion tokens.
RAG or long-document work	Tie	A 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: $0.54.

Larger context near this budget

Llama 4 Scout offers 10M context with $0.23 sample workload cost.
Grok 4.20 offers 2M context with $2.5 sample workload cost.
Owl Alpha offers 1.05M context with $0 sample workload cost.
DeepSeek V4 Flash offers 1.05M context with $0.2 sample workload cost.

Popular competitors

DeepSeek V4 Flash · DeepSeek · #1
Hy3 preview · Tencent · #2
Claude Opus 4.7 · Anthropic · #3
Claude Sonnet 4.6 · Anthropic · #4

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

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

Open provider hubs

Z.ai catalog

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

Open Z.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...

GLM 4.6

Compared with GLM-4.5, this generation brings several key improvements: Longer context window: The context window has been expanded from 128K to 200K tokens, enabling the model to handle more complex...