GLM-5.3-Flash vs GPT-5.5
API pricing, benchmark indices and specs — updated 19 October 2026.
openai · B · API-only
Input / 1M
$5.00
Output / 1M
$30.00
AA index
38.4
proprietary · 1.0M context
Specification comparison
Differences are highlighted; identical values are muted.
| Specification | GLM-5.3-Flash | GPT-5.5 |
|---|---|---|
| Deployment | Open weights · also via API | API-only (closed weights) |
| Parameters | 321.3 B | n/a — API-only |
| Architecture | Glm5NextForConditionalGeneration | n/a — API-only |
| Context length | 1,048,575 | 1,050,000 |
| Licence | mit | Proprietary |
| Commercial use | Allowed | Per API terms |
| Languages | 2 | n/a — API-only |
| Downloads 30d | 6,319,699 | n/a — API-only |
| Downloads all time | 10.3 M | n/a — API-only |
| Quantizations on the Hub | SAFETENSORS | n/a — API-only |
| Gated | No | n/a — API-only |
| First seen on the Hub | 2026-08-25 | n/a — API-only |
| API input price / 1M tokens | $0.15 | $5.00 |
| API output price / 1M tokens | $0.50 | $30.00 |
| Est. cost per 1M input + 1M output tokens | $0.65 | $35.00 |
| Cached input / 1M tokens | $0.03 | $0.50 |
| AA Intelligence Index | 41.8 | 38.4 |
| AA Coding Index | 71.5 | 74.9 |
| AA Agentic Index | 50.9 | 36.4 |
| Max output tokens | 943,717 | 128,000 |
| API providers | 34 | 3 |
| Tool calling | Yes | Yes |
| Reasoning mode | Yes | Yes |
API cost
Estimated cost of 1M input + 1M output tokens via OpenRouter
GLM-5.3-Flash
$0.65
GPT-5.5
$35.00
GLM-5.3-Flash is 53.8× cheaper at list price.
VRAM side by side
On RTX 4090 · 24 GB · 8K context unless noted
GLM-5.3-Flash · fp16
409.9 GB / 24 GB