GPT-5.6 Luna vs GLM-4.5
Side-by-side comparison of API pricing, specs, benchmarks, and capabilities
| Specification |
by OpenAI
|
by Z.AI
|
|---|---|---|
| Overview | ||
| Status | Current mid tier | Current mid tier Open weights |
| Released | Jul 9, 2026 | Jan 1, 2025 |
| Pricing per million tokens | ||
| Input | $0.200/Mtok | $0.600/Mtok |
| Output | $1.20/Mtok | $2.20/Mtok |
| Blended avg | $0.450/Mtok | $1.00/Mtok |
| Cached input | $0.020/Mtok | $0.110/Mtok |
| Specifications | ||
| Context window | 1M tokens | 128K tokens |
| Parameters | Proprietary | Proprietary |
| Speed (TPS) | — | — |
| Modalities | ||
| Input |
textimage
|
text
|
| Benchmarks sources: Vellum LLM Leaderboard / LMSYS Chatbot Arena (UC Berkeley) | ||
| Independent composite scores measured for both models — each on its own scale | ||
| AA-Omniscience Index (−100–100) | -11.2 | -25.4 |
| AA Intelligence Index | 51.2 | — |
| AA Agentic Index | 45.6 | — |
| GDPval-AA v2 | 1581.9 ELO | — |
| LMSYS Chatbot Arena | — | 1410.7 ELO |
| Per-benchmark results published for GPT-5.6 Luna only — no independent per-benchmark scores exist for GLM-4.5 yet | ||
| Avg benchmark score | 90.7 | — |
| Perf / dollar | 201.6 | — |
| GPQA Diamond | 92.3 | — |
| SWE-Bench Verified | 93 | — |
| Terminal-Bench 2.1 | 84.3 | — |
| HumanEval | 93 | — |
| Providers | ||
| Available from |
OpenAI — $0.200/$1.20/Mtok
|
Z.AI — $0.600/$2.20/Mtok
|
Cost at scale
1M tokens · 50/50 input/output| Volume | GPT-5.6 Luna | GLM-4.5 | Savings |
|---|---|---|---|
| 1M tokens | $0.45 | $1 | $0.55 (55%) |
| 10M tokens | $4.5 | $10 | $5.5 (55%) |
| 100M tokens | $45 | $100 | $55 (55%) |
| 1000M tokens | $450 | $1000 | $550 (55%) |
When to pick which
distilled from the pricing and spec data above- cost dominates: $0.450/Mtok blended vs $1.00 — 55% less on the same 50/50 token mix
- your workload re-reads context (agents, RAG, long chats): cached input costs $0.020/Mtok — 90% off its list input price
- you need the longer context: 1M tokens vs 128K (8.2×)
- you want open weights — self-host it, fine-tune it, or exit the API entirely; GPT-5.6 Luna is closed
Price movement
recorded changes since we began tracking each model · last checked Aug 1, 2026| Model | Changes | Latest move | Old → new $/M |
|---|---|---|---|
| GPT-5.6 Luna | 1 | price cut on Aug 1, 2026 | $1/$6 → $0.2/$1.2/Mtok |
| GLM-4.5 | 0 | — no move | Stable since we began tracking — no change recorded |
The cheaper option here — GPT-5.6 Luna costs $0.450/Mtok blended on OpenAI.
Summary
GPT-5.6 Luna by OpenAI costs $0.200/Mtok input and $1.20/Mtok output, with a 1M-token context window. It supports text, image input.
GLM-4.5 by Z.AI costs $0.600/Mtok input and $2.20/Mtok output, with a 128K-token context window. It supports text input.
On a blended cost basis, GPT-5.6 Luna is 55% cheaper than GLM-4.5.It also has a larger context window.
The two aren't directly comparable on average benchmark score: GPT-5.6 Luna has published per-benchmark results, while GLM-4.5 does not yet — it is measured today on independent composites (see the table above).
Note: Pricing is per million tokens. Actual costs vary with usage patterns, prompt caching, and batch discounts. Always verify against official provider pricing pages.