CtrlAltDebrief

GLM 5.1 vs GPT-5.5

API pricing, context window and capabilities for GLM 5.1 and GPT-5.5, side by side. Prices are the cheapest listed serving route per 1M tokens, from LiteLLM and OpenRouter.

Verdict

computed from the published numbers

GLM 5.1 wins on price. GPT-5.5 wins on Terminal-Bench, on intelligence and on context window.

Price
GLM 5.1
Terminal-Bench
GPT-5.5
Intelligence
GPT-5.5
Context window
GPT-5.5

Key takeaways

who wins on what, from the published numbers

GLM 5.1 wins

  • Cheaper input ($1.05 vs $5.00 /1M)
  • Cheaper output ($3.50 vs $30.00 /1M)
  • Higher max output (203K vs 128K)
  • More serving providers (12 vs 6)

GPT-5.5 wins

  • Larger context window (205K vs 1.1M)
  • Supports vision
  • Has web search
Cheaper overall
GLM 5.1
$1.05 + $3.50 /1M
Larger context
GPT-5.5
1.1M
More providers
GLM 5.1
12 providers

Pricing & specs

cheapest listed route · per 1M tokens
On-demand listed rates, OpenRouter routed quotes and Vercel reseller quotes. Enterprise commitments can be materially lower.
GLM 5.1GPT-5.5
Input $/1M$1.05via DeepInfra best$5.00via OpenAI
Output $/1M$3.50via DeepInfra best$30.00via OpenAI
Context window205K 1.1M best
Max output203K best128K
Serving providers12 best6
DateReleased Apr 7, 2026 Released Apr 23, 2026

Benchmarks

Benchmark scores, side by side
GLM 5.1GPT-5.5
Intelligence26.1 38.4 best
Terminal-Bench62% 84% best
GPQA Diamond87% 94% best
Output speed66 t/s 102 t/s best
Latency (TTFT)1.71s best70.60s

Cost calculator

choose a serving route for each side
Input tokens / month
Output tokens / month
GLM 5.1
via DeepInfra
$8.75
GPT-5.5
via OpenAI
$55

Capabilities

feature support, side by side
FeatureGLM 5.1GPT-5.5
Vision—✓
Tool use✓✓
Reasoning✓✓
Audio——
Prompt caching✓✓
Structured output✓✓
Web search—✓

Related comparisons

Frequently asked questions

Which is cheaper, GLM 5.1 or GPT-5.5?
GLM 5.1 is cheaper for input ($1.05 vs $5.00 per 1M tokens) from DeepInfra. GLM 5.1 is cheaper for output ($3.50 vs $30.00 per 1M tokens) from DeepInfra.
What is the context window difference between GLM 5.1 and GPT-5.5?
GLM 5.1 has a 205K-token context window and GPT-5.5 has 1.1M tokens, so GPT-5.5 can take a larger prompt.
How do GLM 5.1 and GPT-5.5 compare on benchmarks?
On the tracked benchmarks, GPT-5.5 leads on Terminal-Bench, and GPT-5.5 leads on intelligence.
Listed prices from LiteLLM, OpenRouter and Vercel · last checked Oct 14, 2026

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