Compare / Claude Fable 5.1 vs Claude Sonnet 4
Claude Fable 5.1 vs Claude Sonnet 4
Which is cheaper, which is more capable, and which does better at each kind of work, from 16 results on 3 sources that measured both models.
Claude Fable 5.1 or Claude Sonnet 4? The short answer
- Claude Sonnet 4 is cheaper: $6.00 against $20.00 per million tokens, 3.3 times less.
- Claude Fable 5.1 scores higher on the Artificial Analysis Intelligence Index: 53.4 against 18.9.
- On our business benchmarks, Claude Fable 5.1 ranks higher for agents and tool use, reasoning and knowledge, writing and sticking to the facts.
At a glance
| Claude Fable 5.1 | Claude Sonnet 4 | |
|---|---|---|
| Price per million tokens | $10.00 in · $50.00 out | $3.00 in · $15.00 out |
| Blended (3 in : 1 out) | $20.00 | $6.00 |
| Cheapest host, blended | $20.00 (Azure) | $6.00 (Amazon Bedrock) |
| Intelligence Index | 53.4 | 18.9 |
| Spring Prompt overall | 65 | – |
| Output speed, tokens a second | 71 | – |
| Context window | 1,000,000 tokens | 200,000 tokens |
| Weights | Closed | Closed |
| Developer based in | the US | the US |
Prices are the developer's list price where we have read it, otherwise the typical host on OpenRouter; see every model's price. Intelligence and speed from Artificial Analysis.
Which is better for what
Each model's rank among models available today, for each kind of work, from our own benchmarks and licensed sources. The better rank is in green.
| Use case | Claude Fable 5.1 | Claude Sonnet 4 |
|---|---|---|
| Product listingsTurning a sparse product feed and photos into listings that can go live | 14 of 19 | not measured |
| Decks from an analysisTurning a finished analysis into a deck you could present as it is | 6 of 18 | not measured |
| Marketing planningPlanning a year of ad spend without overspending | 6 of 18 | not measured |
| Agents and tool useMulti-step tasks with tools: support desks, coding agents, function calls | 14 of 161 | 79 of 161 |
| Professional workReal tasks from banking, consulting and law, business documents and freelance projects | 4 of 51 | not measured |
| Reasoning and knowledgeHard questions across science, maths and general knowledge | 4 of 195 | 111 of 195 |
| WritingWhat people prefer in blind comparisons, and judged writing quality | 15 of 187 | 68 of 187 |
| Sticking to the factsSummarising without inventing things, and factual answers | 4 of 153 | 88 of 153 |
| Speed under pressureGood decisions against a real clock (fast chess) | 22 of 22 | not measured |
Every shared result
| Benchmark | Metric | Claude Fable 5.1 | Claude Sonnet 4 |
|---|---|---|---|
| Arena (formerly LMArena)reported | Business, management and financeArena rating | 1,485 | 1,387 |
| Arena (formerly LMArena)reported | Creative writingArena rating | 1,484 | 1,395 |
| Arena (formerly LMArena)reported | Expert promptsArena rating | 1,516 | 1,433 |
| Arena (formerly LMArena)reported | Instruction followingArena rating | 1,497 | 1,415 |
| Arena (formerly LMArena)reported | OverallArena rating | 1,501 | 1,402 |
| Arena (formerly LMArena)reported | Writing, literature and languageArena rating | 1,496 | 1,398 |
| Artificial Analysisreported | Artificial Analysis Coding Indexindex score | 81.6 | 37.6 |
| Artificial Analysisreported | Artificial Analysis Intelligence Indexindex score | 53.4 | 18.9 |
| Artificial Analysisreported | GPQA Diamond% of questions | 93.7% | 77.7% |
| Artificial Analysisreported | Humanity's Last Exam% of questions | 59.1% | 10.7% |
| Artificial Analysisreported | Long-context reasoning (AA-LCR)% of questions | 85.3% | 70.3% |
| Artificial Analysisreported | Terminal-Bench 2.1% of tasks | 91.4% | 36.3% |
| Artificial Analysisreported | Τ-bench banking% of tasks | 47.2% | 16.7% |
| UGI Leaderboardreported | Requested-length error% off the requested word count | 3.0% | 4.0% |
| UGI Leaderboardreported | Style adherencescore from 0 to 1 | 0.43 | 0.36 |
| UGI Leaderboardreported | Writing scorescore out of 100 | 63.9 | 63.7 |
Bold green marks the better value on that metric. Where a source reports ranges that overlap, the difference may not be meaningful; see the benchmark page for ranges.
Quick answers
Is Claude Fable 5.1 better than Claude Sonnet 4?
It depends on the task. Among models available today, on our benchmarks and licensed sources, Claude Fable 5.1 ranks higher for agents and tool use, reasoning and knowledge, writing and sticking to the facts.
Which is cheaper, Claude Fable 5.1 or Claude Sonnet 4?
Claude Sonnet 4 costs $6.00 per million tokens (three input to one output), against $20.00 for Claude Fable 5.1.
Run Claude Fable 5.1 and Claude Sonnet 4 on your own prompt
Benchmarks aren't your data. Try both side by side in the playground, with the cost of every answer.