Claude Opus 5.5 vs GLM 5.3 Flash
A side-by-side comparison of Claude Opus 5.5 from Anthropic and GLM 5.3 Flash from Z.ai, using published pricing, context windows, supported inputs, and release dates.
- Claude Opus 5.5 input
- $4
- GLM 5.3 Flash input
- $0.0285
Key differences
GLM 5.3 Flash is 99% cheaper on input tokens ($0.0285 vs $4 per 1M).
GLM 5.3 Flash has the larger context window: 1.05M vs 1M tokens.
Claude Opus 5.5 is the newer release (Sep 22, 2026, vs Aug 26, 2026).
Claude Opus 5.5 vs GLM 5.3 Flash specs
| Spec | Claude Opus 5.5 | GLM 5.3 Flash |
|---|---|---|
| Provider | Anthropic | Z.ai |
| Released | Sep 22, 2026 | Aug 26, 2026 |
| Context window | 1,000,000 tokens | 1,048,576 tokens |
| Input price / 1M tokens | $4 | $0.0285 |
| Output price / 1M tokens | $20 | $0.0923 |
| 10K in + 1K out request | $0.06 | $0.00038 |
| Accepts | file, image, text | image, text, video |
| Produces | text | text |
| Tool calling | Yes | Yes |
| Structured outputs | Yes | Yes |
| Reasoning | Yes | Yes |
| Popularity | 47/100 | 57/100 |
Highlighted values are better on that spec: lower price, larger context window, newer release, or higher popularity. Prices in USD per 1M tokens as listed on OpenRouter.
Claude Opus 5.5 vs GLM 5.3 Flash questions
Is Claude Opus 5.5 or GLM 5.3 Flash cheaper?
GLM 5.3 Flash has the lower listed input price ($0.0285 per million tokens). For a request with 10,000 input and 1,000 output tokens, Claude Opus 5.5 costs about $0.06 and GLM 5.3 Flash about $0.00038.
Which has the larger context window?
GLM 5.3 Flash supports 1,048,576 tokens, the larger of the two.
Which model should I choose?
Pick the cheaper model for high-volume, simpler tasks, and test both on a sample of your real prompts before committing. Price and context size do not measure output quality on your specific workload.