Claude Opus 5.5 vs GLM-5.3 Flash: Specs & Benchmark Comparison
Claude Opus 5.5 is developed by Anthropic, while GLM-5.3 Flash comes from Zhipu AI. GLM-5.3 Flash was released in August 2026, and Claude Opus 5.5 followed a month later in September 2026. GLM-5.3 Flash has a published size of about 320 billion parameters; Anthropic has not disclosed the parameter count of Claude Opus 5.5.
The two models share 4 published benchmarks. Claude Opus 5.5 leads on 3 of them, GLM-5.3 Flash on 1. The widest gaps are on Chartography, where Claude Opus 5.5 scores 89.0% against 78.0%; DeepSWE 1.1, where Claude Opus 5.5 scores 74.2% against 63.4%. Averaged across everything we track, Claude Opus 5.5 sits at 71.1% and GLM-5.3 Flash at 64.1%.
GLM-5.3 Flash is the cheaper API at $0.15 per million input tokens and $0.50 per million output tokens, roughly 27 times cheaper than Claude Opus 5.5 at $4 and $20. Both accept a context window of about 1M tokens. Claude Opus 5.5 accepts text and images as input, while GLM-5.3 Flash accepts text, images, and video.
| Characteristic | Claude Opus 5.5 | GLM-5.3 Flash |
|---|---|---|
| Company | Anthropic | Zhipu AI |
| Release Date | September 22, 2026 | August 26, 2026 |
| Parameters | — | 320B |
| Multimodal | Yes | Yes |
| Context (input) | 1.0M | 1.0M |
| Context (output) | 128K | 131K |
| Input Price / 1M | $4.00 | $0.15 |
| Output Price / 1M | $20.00 | $0.50 |
| Average Score | 71.1% | 64.1% |
| Benchmarks | ||
| Chartography | 89.0% | 78.0% |
| DeepSWE 1.1 | 74.2% | 63.4% |
| AutomationBench | 40.0% | 48.8% |
| OfficeQA Pro | 67.7% | 62.4% |
Visual Benchmark Comparison
Verdict
Both models show equal results — the choice depends on your specific use case.
Both models show comparable average scores: Claude Opus 5.5 — 0.7, GLM-5.3 Flash — 0.6.
GLM-5.3 Flash is 36.9x cheaper: input $0.15/1M vs $4.00/1M tokens.
Same context size: 1M tokens.
Claude Opus 5.5 is newer: released 9/22/2026 vs 8/26/2026.
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Frequently Asked Questions
Which is better for coding — Claude Opus 5.5 or GLM-5.3 Flash?
Which model is cheaper — Claude Opus 5.5 or GLM-5.3 Flash?
Which has a larger context window — Claude Opus 5.5 or GLM-5.3 Flash?
The Claude Opus 5.5 and GLM-5.3 Flash comparison is updated for 2026. Data includes benchmark results, API pricing, context window size and other specifications. For more detailed information, visit the Claude Opus 5.5 or GLM-5.3 Flash page. See also the complete list of AI model comparisons.