GLM 5.1 vs GLM 5.2

As of November 12, 2026, GLM 5.1 and GLM 5.2 cost the same: $1.40 per 1M input tokens and $4.40 per 1M output tokens. GLM 5.2 has the larger context window: 1M tokens versus 200K.

Prices from LiteLLM's price fileChecked November 12, 2026

GLM 5.1 vs GLM 5.2 side by side

Headline prices in US dollars per 1M tokens: each model's own lab where it sells it, otherwise its cheapest provider. Source: LiteLLM model price file, as of November 12, 2026.
	GLM 5.1	GLM 5.2
Input, per 1M tokens	$1.40	$1.40
Output, per 1M tokens	$4.40	$4.40
Cache read, per 1M tokens	$0.26	$0.26
Cache write, per 1M tokens	$0	$0
Context window	200,000 tokens	1,000,000 tokens
Max output	128,000 tokens	128,000 tokens
Image input	–	Yes
Tool calling	Yes	Yes
Structured output (JSON)	Yes	Yes
Prompt caching	Yes	Yes
Reasoning	Yes	Yes
Providers on LiteLLM	14	27
Price shown is from	Z.ai	Z.ai
Added to LiteLLM	May 2026	June 2026

Cheapest provider for each

GLM 5.1: EmpirioLabs AI at $0.825 input and $3.301 output per 1M tokens (empiriolabs/glm-5-1)
GLM 5.2: CLF AI Gateway at $0.56 input and $1.76 output per 1M tokens (clf_ai_gateway/glm-5.2)

Benchmark scores

From the Epoch AI Benchmarking Hub (CC BY 4.0), data as of August 29, 2026. Some results were run by Epoch and others collected by Epoch from each benchmark's own leaderboard, linked in the first column. Each model's best reported reasoning setting is shown in brackets. Higher is better. Only benchmarks with a score for both models are shown.
Benchmark	GLM 5.1	GLM 5.2
Coding and agents
APEX-Agents	40.9%	45.2%
Reasoning and knowledge
GPQA Diamond	89.9%	91.9% (max)
SimpleQA Verified	34.0%	34.2% (max)
Math
FrontierMath (tiers 1-3)	36.8%	59.2% (max)
OTIS Mock AIME 2024-2025	93.3%	86.4% (max)

When to pick which

Pick GLM 5.2 for

Larger context window: 1,000,000 vs 200,000 tokens.

From differences in the data above only; where the data is equal, no reason is given.

Call GLM 5.1 or GLM 5.2 with LiteLLM

Both use the OpenAI format through LiteLLM, so switching is a model name change. Set each provider's API key in the environment first.

Python SDK

from litellm import completion

messages = [{"role": "user", "content": "Hello!"}]

# GLM 5.1
response = completion(model="zai/glm-5.1", messages=messages)

# GLM 5.2
response = completion(model="zai/glm-5.2", messages=messages)

# GLM 5.1, falling back to GLM 5.2 if the call fails
response = completion(model="zai/glm-5.1", messages=messages, fallbacks=["zai/glm-5.2"])

FAQ

Which is cheaper, GLM 5.1 or GLM 5.2?

They cost the same: $1.40 per 1M input tokens and $4.40 per 1M output tokens, as of November 12, 2026.

Which has the larger context window, GLM 5.1 or GLM 5.2?

GLM 5.2 has the larger context window: 1,000,000 tokens, versus 200,000 for GLM 5.1.

Can I switch from GLM 5.1 to GLM 5.2 without changing my code?

Yes. Through LiteLLM both use the OpenAI format, so switching means changing the model name from "zai/glm-5.1" to "zai/glm-5.2", or pointing a LiteLLM gateway model alias at the other model. You can also use one as a fallback for the other.