Claude Fable 5.1 vs Mistral Medium 3.5

Claude Fable 5.1 leads Mistral Medium 3.5 on coding, 84.2 to 25.5 on the Vibe Coding Index, and Mistral Medium 3.5 costs 6.7x less per output token ($7.50 vs $50.00 per million). Updated October 22, 2026; 72 benchmarks have a result for both.

Replace Claude Fable 5.1 Replace Mistral Medium 3.5

Claude Fable 5.1Anthropic

Coding: 84.2
Overall: 84.7
Output $/M: $50.00

Mistral Medium 3.5Mistral AI

Coding: 25.5
Overall: 37.3
Output $/M: $7.50

vs boards won of 72 shared

Claude Fable 5.1 or Mistral Medium 3.5: which to pick

Pick Claude Fable 5.1 for coding: it scores 84.2 on the Vibe Coding Index against 25.5 for Mistral Medium 3.5.

Pick Mistral Medium 3.5 for output tokens 6.7x cheaper ($7.50 vs $50.00 per million).

Model AClaude Fable 5.1Anthropic84.2/1005 independent benchmarksNo cost per solved task Model BMistral Medium 3.5Mistral AI25.5/1003 independent benchmarks$6.02 per solved task

726110

Shared results: 72
Claude Fable 5.1 only: 61
Mistral Medium 3.5 only: 10
Like-for-like categories: 8 of 9

Only benchmarks that tested both models count toward a pick; a result only one model has is shown but not compared.

Which one for your work

Each card is decided by one number both models carry. Where only one has it, the card says so and makes no call.

Coding
Vibe Coding Index, six public coding benchmarks
Claude Fable 5.1
Claude Fable 5.1 scores 84.2 against 25.5.
5 and 3 benchmarks behind the scores
Intelligence
AA Intelligence Index
Claude Fable 5.1
Claude Fable 5.1 leads, 53.4 against 14.2.
Same board, both measured
Agentic work
AA Agentic Index
Claude Fable 5.1
Claude Fable 5.1 leads, 57.9 against 7.0.
Same board, both measured
Reasoning
GPQA Diamond
Claude Fable 5.1
Claude Fable 5.1 leads, 93.4% against 34.9%.
Same board, both measured
Knowledge
MMLU Pro
Claude Fable 5.1
Claude Fable 5.1 leads, 92.4% against 75.3%.
Same board, both measured
Web design
Design Arena: websites
Claude Fable 5.1
Claude Fable 5.1 leads, 1312 against 1142.
Same board, both measured
Long documents
Listed context window
Claude Fable 5.1
Claude Fable 5.1 takes 1M tokens against 262K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Mistral Medium 3.5
Claude Fable 5.1 $0.035, Mistral Medium 3.5 $0.0053 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only Mistral Medium 3.5 has the number, $6.02.
Directional only

At a glance

Coding index: Claude Fable 5.1 84.2 from 5 benchmarks, Mistral Medium 3.5 25.5 from 3 benchmarks.
Widest category: Agentic work, 46.8 points apart on average over 5 shared benchmarks.
Widest single gap: ProofBench: Claude Fable 5.1 100.0% against Mistral Medium 3.5 9.0%, 91.0 points apart on a 0 to 100 scale.
Output price: Claude Fable 5.1 $50.00 against Mistral Medium 3.5 $7.50 per million output tokens, 6.7x apart.
Context window: Claude Fable 5.1 takes 1M tokens, Mistral Medium 3.5 262K.

Benchmark by benchmark

First the score: boards each model leads, per category, where both have a result. Then every board, a category to a fold; bars are each result on a 0 to 100 scale, so compare the two in a row, not one row with another.

Boards won, where both have a result
Category	Claude Fable 5.1	Bars	Mistral Medium 3.5	Ties
Coding	11		0
Intelligence	2		0
Agentic work	5		0
Reasoning	8		0
Math	3		0
Knowledge	8		0
Web design	8		0
General	27		0
All shared boards	72		0

CodingLike-for-likeSix of these boards feed the Vibe Coding Index110

Coding benchmarks for Claude Fable 5.1 and Mistral Medium 3.5
Benchmark	Claude Fable 5.1	Mistral Medium 3.5	Leader
LiveBench coding	97.7%	Not measured	Only Claude Fable 5.1 measured
LMArena WebDev	1743	1264	Claude Fable 5.1
AA Coding Index	81.6	46.9	Claude Fable 5.1
LiveCodeBench (Vals AI)	90.5%	Not measured	Only Claude Fable 5.1 measured
SWE-bench Verified (Vals AI)	Not measured	66.4%	Only Mistral Medium 3.5 measured
Terminal-Bench 4 (Vals AI)	58.1%	Not measured	Only Claude Fable 5.1 measured
Vibe Code Bench (Vals AI)	90.3%	2.9%	Claude Fable 5.1
Code migration (Vals AI)	54.6%	5.1%	Claude Fable 5.1
ProgramBench (Vals AI)	7.0%	Not measured	Only Claude Fable 5.1 measured
IOI (Vals AI)	90.8%	Not measured	Only Claude Fable 5.1 measured
Terminal-Bench 2.1 (Vals AI)	85.0%	39.0%	Claude Fable 5.1
SWE-bench Multimodal (Vals AI)	61.3%	Not measured	Only Claude Fable 5.1 measured
Vibe Code Bench 1-100 (Vals AI)	28.0%	Not measured	Only Claude Fable 5.1 measured
SkillsBench (Vals AI)	61.5%	Not measured	Only Claude Fable 5.1 measured
CyberBench (Vals AI)	70.4%	Not measured	Only Claude Fable 5.1 measured
SciCode	63.1%	40.2%	Claude Fable 5.1
Terminal-Bench Hard (Artificial Analysis run)	Not measured	33.3%	Only Mistral Medium 3.5 measured
FrontierCode	50.9%	Not measured	Only Claude Fable 5.1 measured
FrontierSWE	56.3%	Not measured	Only Claude Fable 5.1 measured
GSO-Bench	88.2%	Not measured	Only Claude Fable 5.1 measured
WeirdML	92.9%	Not measured	Only Claude Fable 5.1 measured
MirrorCode	73.3%	Not measured	Only Claude Fable 5.1 measured
ALE-Bench	2143.2	764.0	Claude Fable 5.1
LMArena Text: coding	1532	1460	Claude Fable 5.1
LMArena Text: software and IT	1530	1458	Claude Fable 5.1
LMArena WebDev: React	1792	1254	Claude Fable 5.1
LMArena WebDev: HTML	1684	1308	Claude Fable 5.1
LMArena WebDev: from an image	1722	Not measured	Only Claude Fable 5.1 measured
SWE-Bench Pro V2	99.1%	Not measured	Only Claude Fable 5.1 measured
SWE Atlas: Codebase QnA	60.0%	Not measured	Only Claude Fable 5.1 measured
SWE Atlas: Refactoring	56.7%	Not measured	Only Claude Fable 5.1 measured
SWE Atlas: Test Writing	67.0%	Not measured	Only Claude Fable 5.1 measured
Neither model has a result on the other 11 boards here

IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20

Intelligence benchmarks for Claude Fable 5.1 and Mistral Medium 3.5
Benchmark	Claude Fable 5.1	Mistral Medium 3.5	Leader
AA Intelligence Index	53.4	14.2	Claude Fable 5.1
Epoch Capabilities Index	166.5	141.4	Claude Fable 5.1

Agentic workLike-for-likePublic boards, shown as published, kept out of the index50

Agentic work benchmarks for Claude Fable 5.1 and Mistral Medium 3.5
Benchmark	Claude Fable 5.1	Mistral Medium 3.5	Leader
AA Agentic Index	57.9	7.0	Claude Fable 5.1
Design Arena: agents building web apps	1318	Not measured	Only Claude Fable 5.1 measured
Design Arena: agents building full-stack apps	1326	Not measured	Only Claude Fable 5.1 measured
Design Arena: agents building mobile apps	1267	Not measured	Only Claude Fable 5.1 measured
Design Arena: agents building Godot games	1327	Not measured	Only Claude Fable 5.1 measured
Design Arena: PowerPoint slides	1307	Not measured	Only Claude Fable 5.1 measured
Design Arena: spreadsheets	1394	Not measured	Only Claude Fable 5.1 measured
LiveBench research	82.0%	Not measured	Only Claude Fable 5.1 measured
LiveBench browser	100.0%	Not measured	Only Claude Fable 5.1 measured
LiveBench long agentic	80.8%	Not measured	Only Claude Fable 5.1 measured
SREBench (Vals AI)	22.9%	Not measured	Only Claude Fable 5.1 measured
Finance Agent (Vals AI)	58.9%	32.1%	Claude Fable 5.1
Tax Agent Bench (Vals AI)	49.2%	4.5%	Claude Fable 5.1
Legal Research Bench (Vals AI)	55.3%	9.1%	Claude Fable 5.1
Excel Modeling Benchmark (Vals AI)	76.7%	11.2%	Claude Fable 5.1
Terminal-Bench-Science (Vals AI)	40.0%	Not measured	Only Claude Fable 5.1 measured
Time Horizon Index (Vals AI)	63.3%	Not measured	Only Claude Fable 5.1 measured
CUA-bench (Vals AI)	13.2%	Not measured	Only Claude Fable 5.1 measured
Robo-bench (Vals AI)	5.8%	Not measured	Only Claude Fable 5.1 measured
τ²-Bench Telecom	Not measured	94.2%	Only Mistral Medium 3.5 measured
APEX-Agents	68.6%	Not measured	Only Claude Fable 5.1 measured
Remote Labor Index	17.9%	Not measured	Only Claude Fable 5.1 measured
SpireClimb	2.0%	Not measured	Only Claude Fable 5.1 measured
Vending-Bench 2	$5,422	Not measured	Only Claude Fable 5.1 measured
LMArena Search	1246	Not measured	Only Claude Fable 5.1 measured
MCP Atlas	87.2%	Not measured	Only Claude Fable 5.1 measured
Neither model has a result on the other 16 boards here

ReasoningLike-for-likePublic boards, shown as published, kept out of the index80

Reasoning benchmarks for Claude Fable 5.1 and Mistral Medium 3.5
Benchmark	Claude Fable 5.1	Mistral Medium 3.5	Leader
GPQA Diamond	93.4%	34.9%	Claude Fable 5.1
LiveBench reasoning	91.7%	Not measured	Only Claude Fable 5.1 measured
MysteryMechanism (Vals AI)	47.8%	Not measured	Only Claude Fable 5.1 measured
MMMU Pro (Vals AI)	90.6%	Not measured	Only Claude Fable 5.1 measured
GPQA Diamond (Artificial Analysis run)	93.7%	74.8%	Claude Fable 5.1
Humanity's Last Exam (Artificial Analysis run)	59.1%	13.8%	Claude Fable 5.1
ARC-AGI	97.5%	Not measured	Only Claude Fable 5.1 measured
ARC-AGI-2	90.0%	Not measured	Only Claude Fable 5.1 measured
Chess puzzles	48.0%	Not measured	Only Claude Fable 5.1 measured
Mystery game puzzles	58.0%	Not measured	Only Claude Fable 5.1 measured
EBR-bench	57.1%	Not measured	Only Claude Fable 5.1 measured
LMArena Text: hard prompts	1528	1436	Claude Fable 5.1
LMArena Text: expert	1544	1432	Claude Fable 5.1
LMArena Text: hard prompts in English	1522	1445	Claude Fable 5.1
LMArena Vision: diagrams	1343	1254	Claude Fable 5.1
LMArena Vision: homework	1345	1230	Claude Fable 5.1
Kagi LLM Benchmark	Not measured	41.4%	Only Mistral Medium 3.5 measured
Humanity's Last Exam (Scale run)	51.3%	Not measured	Only Claude Fable 5.1 measured
Neither model has a result on the other 5 boards here

MathLike-for-likePublic boards, shown as published, kept out of the index30

Math benchmarks for Claude Fable 5.1 and Mistral Medium 3.5
Benchmark	Claude Fable 5.1	Mistral Medium 3.5	Leader
OTIS Mock AIME	100.0%	Not measured	Only Claude Fable 5.1 measured
FrontierMath, tiers 1 to 3	90.2%	Not measured	Only Claude Fable 5.1 measured
FrontierMath, tier 4	87.8%	Not measured	Only Claude Fable 5.1 measured
ProofBench	100.0%	9.0%	Claude Fable 5.1
LMArena Text: math	1531	1431	Claude Fable 5.1
LMArena Text: mathematical work	1541	1440	Claude Fable 5.1
MathArena	78.1%	Not measured	Only Claude Fable 5.1 measured
Neither model has a result on the other 7 boards here

KnowledgeLike-for-likePublic boards, shown as published, kept out of the index80

Knowledge benchmarks for Claude Fable 5.1 and Mistral Medium 3.5
Benchmark	Claude Fable 5.1	Mistral Medium 3.5	Leader
MMLU Pro	92.4%	75.3%	Claude Fable 5.1
LegalBench (Vals AI)	88.5%	Not measured	Only Claude Fable 5.1 measured
CaseLaw (Vals AI)	Not measured	44.2%	Only Mistral Medium 3.5 measured
CorpFin (Vals AI)	Not measured	58.8%	Only Mistral Medium 3.5 measured
TaxEval (Vals AI)	76.0%	68.0%	Claude Fable 5.1
MortgageTax (Vals AI)	70.8%	28.9%	Claude Fable 5.1
MedCode (Vals AI)	53.5%	33.8%	Claude Fable 5.1
SimpleQA Verified	70.8%	Not measured	Only Claude Fable 5.1 measured
LMArena Text: science	1532	1428	Claude Fable 5.1
LMArena Text: medicine and healthcare	1531	1409	Claude Fable 5.1
LMArena Text: legal and government	1514	1437	Claude Fable 5.1
LMArena Text: business and finance	1493	1426	Claude Fable 5.1
PRBench Finance	50.8%	Not measured	Only Claude Fable 5.1 measured
PRBench Legal	51.6%	Not measured	Only Claude Fable 5.1 measured
Neither model has a result on the other 6 boards here

Web designLike-for-likePublic boards, shown as published, kept out of the index80

Web design benchmarks for Claude Fable 5.1 and Mistral Medium 3.5
Benchmark	Claude Fable 5.1	Mistral Medium 3.5	Leader
Design Arena: websites	1312	1142	Claude Fable 5.1
Design Arena: UI components	1336	1076	Claude Fable 5.1
Design Arena: game dev	1381	1079	Claude Fable 5.1
Design Arena: data viz	1345	1121	Claude Fable 5.1
Design Arena: 3D	1392	1060	Claude Fable 5.1
Design Arena: all code categories	1335	1121	Claude Fable 5.1
Design Arena: SVG	1300	949	Claude Fable 5.1
Design Arena: ASCII art	1323	1062	Claude Fable 5.1
LiveBench design	83.4%	Not measured	Only Claude Fable 5.1 measured

GeneralLike-for-likePublic boards, shown as published, kept out of the index270

General benchmarks for Claude Fable 5.1 and Mistral Medium 3.5
Benchmark	Claude Fable 5.1	Mistral Medium 3.5	Leader
LiveBench data analysis	80.3%	Not measured	Only Claude Fable 5.1 measured
Public Benefits Bench (Vals AI)	74.9%	Not measured	Only Claude Fable 5.1 measured
SAGE (Vals AI)	48.5%	37.6%	Claude Fable 5.1
MedScribe (Vals AI)	91.3%	67.7%	Claude Fable 5.1
Vals Multimodal Index	Not measured	34.8%	Only Mistral Medium 3.5 measured
IFBench	Not measured	68.8%	Only Mistral Medium 3.5 measured
Long context reasoning (AA-LCR)	85.3%	69.3%	Claude Fable 5.1
DTBench	97.6%	75.5%	Claude Fable 5.1
LMCA	65.5%	26.1%	Claude Fable 5.1
Surface Evolver Bench	Not measured	26.9%	Only Mistral Medium 3.5 measured
Furniture assembly	70.0%	Not measured	Only Claude Fable 5.1 measured
LMArena Text	1512	1421	Claude Fable 5.1
LMArena Text: instruction following	1518	1415	Claude Fable 5.1
LMArena Text: creative writing	1509	1374	Claude Fable 5.1
LMArena Vision	1319	1222	Claude Fable 5.1
LMArena Text: English	1506	1433	Claude Fable 5.1
LMArena Text: non-English	1508	1404	Claude Fable 5.1
LMArena Text: Chinese	1584	1444	Claude Fable 5.1
LMArena Text: German	1499	1453	Claude Fable 5.1
LMArena Text: Japanese	1562	Not measured	Only Claude Fable 5.1 measured
LMArena Text: Korean	1517	1384	Claude Fable 5.1
LMArena Text: French	1523	1448	Claude Fable 5.1
LMArena Text: Spanish	1520	1411	Claude Fable 5.1
LMArena Text: Russian	1520	1395	Claude Fable 5.1
LMArena Text: Polish	1525	1430	Claude Fable 5.1
LMArena Text: multi-turn	1493	1423	Claude Fable 5.1
LMArena Text: longer queries	1524	1415	Claude Fable 5.1
LMArena Text: writing and language	1510	1384	Claude Fable 5.1
LMArena Text: entertainment and media	1497	1382	Claude Fable 5.1
LMArena Vision: English	1313	1240	Claude Fable 5.1
LMArena Vision: Chinese	1391	1244	Claude Fable 5.1
LMArena Vision: reading text	1327	1233	Claude Fable 5.1
LMArena Vision: humor	1318	1216	Claude Fable 5.1
LMArena Vision: creative writing	1330	1198	Claude Fable 5.1
EQ-Bench 4	Not measured	993	Only Mistral Medium 3.5 measured
Neither model has a result on the other 13 boards here

Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared

Image generation benchmarks for Claude Fable 5.1 and Mistral Medium 3.5
Benchmark	Claude Fable 5.1	Mistral Medium 3.5	Leader
Neither model has a result on 5 boards here

What each workload costs

Three fixed token mixes at each model's listed price, so per-token rates become a bill.

Chat turn

1K input + 500 output tokens

Claude Fable 5.1$0.035Fits in one request

Mistral Medium 3.5$0.0053Fits in one request

Mistral Medium 3.5 costs less

Repository review

50K input + 3K output tokens

Claude Fable 5.1$0.650Fits in one request

Mistral Medium 3.5$0.098Fits in one request

Mistral Medium 3.5 costs less

Agent loop

200K input + 10K output tokens

Claude Fable 5.1$2.50Fits in one request

Mistral Medium 3.5$0.375Fits in one request

Mistral Medium 3.5 costs less

Listed OpenRouter rates, without cache or batch discounts. A workload that does not fit a model's context window would need splitting.

Specification differences

The leading value in a row is marked; a row with a missing value names no leader. Our two rows are marked in red.

Specifications of Claude Fable 5.1 and Mistral Medium 3.5
Specification	Anthropic Claude Fable 5.1	Mistral Medium 3.5
Maker	Anthropic	Mistral AI
Weights	No public weights listed	No public weights listed
Released	September 1, 2026	April 30, 2026
Context window	1M	262K
Input $/Mtok	$10.00	$1.50
Output $/Mtok	$50.00	$7.50
Coding index	84.2	25.5
Independent measurements behind it	5	3
Cost per solved task	Not computable	$6.02
Source	OpenRouter listing	OpenRouter listing

Questions

Is Claude Fable 5.1 better than Mistral Medium 3.5 for coding?

Pick Claude Fable 5.1 for coding: it scores 84.2 on the Vibe Coding Index against 25.5 for Mistral Medium 3.5. Pick Mistral Medium 3.5 for output tokens 6.7x cheaper ($7.50 vs $50.00 per million).

Which is cheaper, Claude Fable 5.1 or Mistral Medium 3.5?

Claude Fable 5.1 costs $10.00 per million input tokens and $50.00 per million output tokens; Mistral Medium 3.5 costs $1.50 and $7.50. Cost per solved task is known for Mistral Medium 3.5 only.

Which has the bigger context window, Claude Fable 5.1 or Mistral Medium 3.5?

Claude Fable 5.1, with 1M tokens against 262K.

How many benchmarks is the Claude Fable 5.1 vs Mistral Medium 3.5 comparison based on?

72 benchmarks have a result for both models as of October 22, 2026. Claude Fable 5.1's coding index rests on 5 independent benchmarks and Mistral Medium 3.5's on 3. Where only one model has a result, the page says so instead of naming a winner.

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Claude Fable 5.1 or Mistral Medium 3.5: which to pick

Which one for your work

Coding

Intelligence

Agentic work

Reasoning

Knowledge

Web design

Long documents

Everyday cost

Cost per solved task

At a glance

Benchmark by benchmark

What each workload costs

Chat turn

Repository review

Agent loop

Specification differences

Questions

Compare next