Model Comparison
GLM-5 (Reasoning)
vs. GPT-5.5 Instant (May 2026)
Comparing 2 AI models · 7 benchmarks · Z AI, OpenAI
Recommended Pick
Z GLM-5 (Reasoning) 12 metric wins Strongest on: Value, Input price, Output price
Best Value
GLM-5 (Reasoning)
100.0 value score
53.0 reasoning / $1.55/1M
Lowest Price
GLM-5 (Reasoning)
$1.00/1M input price
Best Reasoning
GLM-5 (Reasoning)
53.0 reasoning score
Blends available reasoning benchmarks
Best for Coding
GPT-5.5 Instant (May 2026)
45.1 coding index
Composite Indices
Higher is better; speed and price are normalized
Standard Benchmarks
Only benchmarks with data are shown
Differences That Matter
Best value
GLM-5 (Reasoning) has the strongest quality-to-price mix at 100.0 out of 100 value points.
Price gap
GLM-5 (Reasoning) is 5.0x cheaper on input tokens than GPT-5.5 Instant (May 2026).
Reasoning gap
GLM-5 (Reasoning) leads GPT-5.5 Instant (May 2026) by 4.1 points on reasoning.
Coding gap
GPT-5.5 Instant (May 2026) leads GLM-5 (Reasoning) by 0.9 points on coding.
Top-pick rationale
GLM-5 (Reasoning) wins 12 measurable categories, including Value, Input price, Output price, Blended price.
Response Face-Off
Run one prompt through the selected models and compare response quality with live speed and cost context.
GLM-5 (Reasoning)
Z AI
TTFT
—
Time
—
tok/s
—
Tokens
—
Cost
—
GPT-5.5 Instant (May 2026)
OpenAI
TTFT
—
Time
—
tok/s
—
Tokens
—
Cost
—
Which answer was more useful?
Full Comparison
| Metric | Top Pick Z GLM-5 (Reasoning) | Op GPT-5.5 Instant (May 2026) |
|---|---|---|
| Pricing per 1M tokens | ||
| Input Cost | $1.00/1M | $5.00/1M |
| Output Cost | $3.20/1M | $30.00/1M |
| Blended (3:1) | $1.55/1M | $11.25/1M |
| Specifications | ||
| Organization | Z AI | OpenAI |
| Release Date | Feb 11, 2026 | May 5, 2026 |
| Performance & Speed | ||
| Throughput | 81.4 tok/s | — |
| TTFT | 867ms | — |
| Latency | 39005ms | — |
| Composite Indices | ||
| Value Score | 100.0 | 12.7 |
| Reasoning Score | 53.0 | 48.9 |
| Intelligence | 49.8 | 41.8 |
| Coding | 44.2 | 45.1 |
| Standard Benchmarks | ||
| GPQA | 82.0% | 84.6% |
| HLE | 27.2% | 20.3% |
| SciCode | 46.2% | 50.3% |
| LCR | 63.3% | 55.7% |
| IFBench | 72.3% | 71.5% |
| TAU-bench v2 | 98.2% | 49.4% |
| TerminalBench Hard | 43.2% | 42.4% |
Key Takeaways
GLM-5 (Reasoning) offers the best value at $1.00/1M, making it ideal for high-volume applications and cost-conscious projects.
GLM-5 (Reasoning) has the strongest reasoning profile with a 53.0 reasoning score, combining the available reasoning-heavy benchmarks.
GPT-5.5 Instant (May 2026) reaches a 45.1 coding index, making it the top choice for software development and code generation tasks.
All models support context windows of ∞+ tokens, suitable for processing lengthy documents and maintaining extended conversations.
When to Choose Each Model
GLM-5 (Reasoning)
- Cost-sensitive applications
- High-volume processing
- Complex reasoning tasks
- Research & analysis
GPT-5.5 Instant (May 2026)
- Code generation
- Software development
