Claude Fable 5.2 vs GLM-5.3-Flash
Claude Fable 5.2 and GLM-5.3-Flash are within three points on the Models at Work leaderboard, which we treat as a tie (71 vs 71 out of 100). On independent tests alone, Claude Fable 5.2 is ahead (100 vs 61). GLM-5.3-Flash is cheaper: 1,000 support replies cost about $0.65 at list price, against $40 on Claude Fable 5.2, which is 62 times as much. On the Artificial Analysis Intelligence Index, one of the independent tests, Claude Fable 5.2 leads 65 to 28.
| Claude Fable 5.2 · Anthropic | GLM-5.3-Flash · Z.ai | |
|---|---|---|
| Leaderboard rank | #3 | #4 |
| Score (0–100) | 71 | 71 |
| Kind of work | Hardest problems | Run it yourself |
| Price per 1M tokens | $8 to read · $40 to write | $0.15 to read · $0.50 to write |
| Reads at once | 1M tokens (about 750,000 words) | 1M tokens (about 750,000 words) |
| Where you can get it | Claude Team and Enterprise, Amazon Bedrock, Gemini Enterprise Agent Platform (Google Cloud), Microsoft Foundry | Z.ai API |
| Can a company host it itself | No | Yes (open weights) |
| Artificial Analysis Intelligence Index | 65 | 28 |
| Humanity's Last Exam, Diamond (Scale) | 72.40 | Not measured |
| Humanity's Sixth Sense (Scale) | 59.50 | 26.80 |
| Epoch Capabilities Index | 173 | Not measured |
| Arena Text score | Not measured | 1475 (rank 38) |
| Arena WebDev score | Not measured | 1609 (rank 26) |
| Best for | Financial and technical analysis with no room for error, Multi-step research, Work Claude Opus 5.5 gets wrong | Bulk document and image processing, Routine steps planned by a stronger model, Running AI on your own servers |
Cost of 1,000 jobs
| 1,000 of these | Claude Fable 5.2 | GLM-5.3-Flash |
|---|---|---|
| Support repliesthe customer message, the account notes and two help articles read; a 300-word reply written | $40 | $0.65 |
| Documents processeda two-page invoice or form read; the fields pulled out | $28 | $0.45 |
| Calls summariseda 40-minute call transcript read; a summary and next steps written | $104 | $1.80 |
| Contracts revieweda 40-page contract read against a checklist; a memo of issues written | $300 | $5.25 |
| Drafts writtena brief and one example read; a 600-word email or proposal section written | $44 | $0.63 |
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 Claude Fable 5.2 for
- Financial and technical analysis with no room for error
- Multi-step research
- Work Claude Opus 5.5 gets wrong
The strongest model on the board for problems the others get wrong: first on every independent test read, at twice the list price of Claude Opus 5.5.
Caveats: Anthropic's own advice is to start with Opus 5.5 and move up only when its answers fall short. It writes more per answer: Artificial Analysis's test run cost $26.54 per task at the top effort setting against $10.04 for Opus 5.5, a wider gap than the list prices suggest. On Claude Team it is offered on premium seats, up to half the weekly usage limit; Enterprise bills usage at API rates, per Anthropic's pricing page. Mythos 5.2 is the same model without the cyber and biology safeguards, open only through Anthropic's verification programs. It ranks third, not first, because price is 30% of the score and this is the second most expensive model here; on independent test results alone it is first.
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.
What people running them say
Claude Fable 5.2: One Hacker News (developer forum) launch thread, read through Signals: a commenter who tried it says it pulls ahead of Opus 5.5 only on very ambitious requests, another says Opus 5.5 at a high effort setting was enough for a software project of 125,000 lines, and a third asks how anyone measures the difference at the price. Too little to score.
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'.
Questions people ask
Which is better, Claude Fable 5.2 or GLM-5.3-Flash?
Claude Fable 5.2 and GLM-5.3-Flash are within three points on the Models at Work leaderboard, which we treat as a tie (71 vs 71 out of 100). On independent tests alone, Claude Fable 5.2 is ahead (100 vs 61). GLM-5.3-Flash is cheaper: 1,000 support replies cost about $0.65 at list price, against $40 on Claude Fable 5.2, which is 62 times as much. On the Artificial Analysis Intelligence Index, one of the independent tests, Claude Fable 5.2 leads 65 to 28.
When should I choose Claude Fable 5.2 over GLM-5.3-Flash?
Choose Claude Fable 5.2 for financial and technical analysis with no room for error, multi-step research, work claude opus 5.5 gets wrong. The strongest model on the board for problems the others get wrong: first on every independent test read, at twice the list price of Claude Opus 5.5.
When should I choose GLM-5.3-Flash over Claude Fable 5.2?
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.
Which is cheaper, Claude Fable 5.2 or GLM-5.3-Flash?
Claude Fable 5.2 costs $8 per million tokens it reads (input) and $40 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. 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.
What do 1,000 jobs cost on Claude Fable 5.2 and GLM-5.3-Flash?
At list price: 1,000 support replies cost $40 on Claude Fable 5.2 and $0.65 on GLM-5.3-Flash; 1,000 documents processed cost $28 on Claude Fable 5.2 and $0.45 on GLM-5.3-Flash; 1,000 calls summarised cost $104 on Claude Fable 5.2 and $1.80 on GLM-5.3-Flash; 1,000 contracts reviewed cost $300 on Claude Fable 5.2 and $5.25 on GLM-5.3-Flash; 1,000 drafts written cost $44 on Claude Fable 5.2 and $0.63 on GLM-5.3-Flash. 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.