GLM-5.3-Flash vs Claude Opus 5.5
GLM-5.3-Flash and Claude Opus 5.5 are within three points on the Models at Work leaderboard, which we treat as a tie (71 vs 70 out of 100). On independent tests alone, Claude Opus 5.5 is ahead (83 vs 61). GLM-5.3-Flash is cheaper: 1,000 support replies cost about $0.65 at list price, against $20 on Claude Opus 5.5, which is 31 times as much. On the Artificial Analysis Intelligence Index, one of the independent tests, Claude Opus 5.5 leads 59 to 28.
| GLM-5.3-Flash · Z.ai | Claude Opus 5.5 · Anthropic | |
|---|---|---|
| Leaderboard rank | #4 | #5 |
| Score (0–100) | 71 | 70 |
| Kind of work | Run it yourself | Hardest problems |
| Price per 1M tokens | $0.15 to read · $0.50 to write | $4 to read · $20 to write |
| Reads at once | 1M tokens (about 750,000 words) | 1M tokens (about 750,000 words) |
| Where you can get it | Z.ai API | Claude Team and Enterprise, Amazon Bedrock, Gemini Enterprise Agent Platform (Google Cloud), Microsoft Foundry, Microsoft 365 Copilot, GitHub Copilot |
| Can a company host it itself | Yes (open weights) | No |
| Artificial Analysis Intelligence Index | 28 | 59 |
| Arena Text score | 1475 (rank 38) | Not measured |
| Arena WebDev score | 1609 (rank 26) | Not measured |
| Humanity's Sixth Sense (Scale) | 26.80 | 44.60 |
| Arena text score | Not measured | 1507 |
| Humanity's Last Exam, Diamond (Scale) | Not measured | 55.00 |
| Epoch Capabilities Index | Not measured | 167 |
| Best for | Bulk document and image processing, Routine steps planned by a stronger model, Running AI on your own servers | Long reports and analysis, Reading long contracts, Multi-step research, Work a cheaper model gets wrong |
Cost of 1,000 jobs
| 1,000 of these | GLM-5.3-Flash | Claude Opus 5.5 |
|---|---|---|
| Support repliesthe customer message, the account notes and two help articles read; a 300-word reply written | $0.65 | $20 |
| Documents processeda two-page invoice or form read; the fields pulled out | $0.45 | $14 |
| Calls summariseda 40-minute call transcript read; a summary and next steps written | $1.80 | $52 |
| Contracts revieweda 40-page contract read against a checklist; a memo of issues written | $5.25 | $150 |
| Drafts writtena brief and one example read; a 600-word email or proposal section written | $0.63 | $22 |
Worked out from each vendor’s list price and a fixed size for each job. A product built on a model charges its own price on top. See what every model costs for the same jobs.
Choose GLM-5.3-Flash for
- Bulk document and image processing
- Routine steps planned by a stronger model
- Running AI on your own servers
Cheap enough for bulk work at roughly a tenth of GLM-5.3's list price, scoring 28 against 32 on Artificial Analysis's index; despite the name it is not fast.
Caveats: Slow on Z.ai's own service: about 60 tokens (word-pieces) a second, under half the speed of the fast models on this board. Users report less consistent output than the full GLM-5.3; the common pattern is a stronger model writing the plan and this one carrying it out. Running it yourself still needs a server with several high-end graphics cards. Not found on a major US cloud this run: Z.ai's own service or your own servers only.
Choose Claude Opus 5.5 for
- Long reports and analysis
- Reading long contracts
- Multi-step research
- Work a cheaper model gets wrong
The safer buy for hard work: six points behind Claude Fable 5.2 on Artificial Analysis's index (59 against 65) at half its list price, and the model Anthropic says to start with.
Caveats: Twice the list price of Claude Sonnet 5.5; test your own work on Sonnet before paying for this one. On Arena, where people vote blind between two models' answers, Gemini 4 Argon is ahead, but the gap is within the margin of error. In Microsoft 365 Copilot, Claude models are off by default in the EU, EFTA and UK until an administrator allows Anthropic as a subprocessor (a company permitted to handle your data), per Microsoft.
What people running them say
GLM-5.3-Flash: A developer's month-long diary on Hacker News, a developer forum ('One month coding with GLM 5.3 Flash', 233 upvotes), reports a total bill of $68 for a month of having the model write and change software largely on its own; commenters agreed that figure 'is the headline'. The pattern they describe is to have the larger GLM-5.3 write the plan and Flash carry it out; one user notes that given an unambiguous plan 'GLM 5.3 Flash executes it just fine'. The complaints: on Z.ai's own service it is 'too slow for execution, despite the name', and the full model is 'way more consistent'.
Claude Opus 5.5: Its launch thread was the year's biggest about a Claude model on Hacker News, a developer forum. One project there credited the model with rewriting a large piece of programming software (the TypeScript compiler) in another programming language, Rust, to a working state in ten hours, and a Vals AI materials-discovery run used it to run simulations on its own. The most-upvoted doubt is a tracker asking whether the model has been quietly made worse since launch.
Questions people ask
Which is better, GLM-5.3-Flash or Claude Opus 5.5?
GLM-5.3-Flash and Claude Opus 5.5 are within three points on the Models at Work leaderboard, which we treat as a tie (71 vs 70 out of 100). On independent tests alone, Claude Opus 5.5 is ahead (83 vs 61). GLM-5.3-Flash is cheaper: 1,000 support replies cost about $0.65 at list price, against $20 on Claude Opus 5.5, which is 31 times as much. On the Artificial Analysis Intelligence Index, one of the independent tests, Claude Opus 5.5 leads 59 to 28.
When should I choose GLM-5.3-Flash over Claude Opus 5.5?
Choose GLM-5.3-Flash for bulk document and image processing, routine steps planned by a stronger model, running ai on your own servers. Cheap enough for bulk work at roughly a tenth of GLM-5.3's list price, scoring 28 against 32 on Artificial Analysis's index; despite the name it is not fast.
When should I choose Claude Opus 5.5 over GLM-5.3-Flash?
Choose Claude Opus 5.5 for long reports and analysis, reading long contracts, multi-step research, work a cheaper model gets wrong. The safer buy for hard work: six points behind Claude Fable 5.2 on Artificial Analysis's index (59 against 65) at half its list price, and the model Anthropic says to start with.
Which is cheaper, GLM-5.3-Flash or Claude Opus 5.5?
GLM-5.3-Flash costs $0.15 per million tokens it reads (input) and $0.50 per million tokens it writes (output) on Z.ai's list price (Z.ai Pricing, read Nov 12, 2026). A token is about three-quarters of a word. Claude Opus 5.5 costs $4 per million tokens it reads (input) and $20 per million tokens it writes (output) on Anthropic's list price (Claude pricing, read Nov 12, 2026). A token is about three-quarters of a word.
What do 1,000 jobs cost on GLM-5.3-Flash and Claude Opus 5.5?
At list price: 1,000 support replies cost $0.65 on GLM-5.3-Flash and $20 on Claude Opus 5.5; 1,000 documents processed cost $0.45 on GLM-5.3-Flash and $14 on Claude Opus 5.5; 1,000 calls summarised cost $1.80 on GLM-5.3-Flash and $52 on Claude Opus 5.5; 1,000 contracts reviewed cost $5.25 on GLM-5.3-Flash and $150 on Claude Opus 5.5; 1,000 drafts written cost $0.63 on GLM-5.3-Flash and $22 on Claude Opus 5.5. A product built on either model charges its own price on top.
Scores come from the Models at Work leaderboard: Score is 0 to 100 and computed, not typed. 40% is independent testing (Artificial Analysis, Arena, Scale, Epoch, Vals and others; each test is scaled against the best score on this board, and tests of real work, such as finished freelance projects or professional tasks, count double the exams). 30% is price: the vendor's list price for a typical mix of reading and writing, on a fixed scale from $0.05 to $60 per million tokens, so a model that costs a fifth as much gains real ground. 15% is what people report after running it, from Signals and linked threads. 15% is fit: how much text it can take in at once and where a business can get it (the products and clouds that carry it), with a small credit for open weights. A missing component drops out and the rest are reweighted. A model with no independent test yet is provisional and ranks below every measured one. Within three points is a tie. Vendor-published figures are labelled and never counted. Prices are vendor list prices where published; a typical mix assumes three parts reading to one part writing.