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Model comparison

Claude Opus 5.5 vs Mistral Large 3

Anthropic against Mistral, compared on context, price, and verified benchmark results.

Catalog record checked September 26, 2026Individual provider fields may changeEvidence confidence: High — see receipts below

Anthropic

Claude Opus 5.5

Frontier

vs

Mistral

Mistral Large 3

Frontier · Open weights

AI model capability comparison
SpecificationClaude Opus 5.5Mistral Large 3
ProviderAnthropicMistral
TierFrontierFrontier
Context windowWinner: 1M262K
Max output128KNot verifiedUnverified
Input / 1M tokens$4Winner: $0.50
Output / 1M tokens$20Winner: $1.50
WeightsClosedOpen
ParametersNot disclosedUnverified675B total / 41B active (sparse MoE)
Reasoning levelsadaptiveNot verifiedUnverified
Modalitiestext, imagetext, image
LicenseNot disclosedUnverifiedApache 2.0
API model idclaude-opus-5-5mistral-large-2512
ReleasedSeptember 22, 2026December 2, 2025
Artificial Analysis Intelligence Index [max] (2026-09-26)57.6Not verifiedUnverified
Artificial Analysis Intelligence Index (2026-09-26)Not verifiedUnverified9.3
Humanity's Last Exam [max] (2026-09-26)61.4Not verifiedUnverified
Terminal-Bench 4.0 [max] (2026-09-26)59.6Not verifiedUnverified
Terminal-Bench 4.0 [xhigh] (2026-09-22)66.4Not verifiedUnverified
GPQA Diamond (2026-09-26)Not verifiedUnverified68

Prices are USD per million tokens at standard rates, excluding batch and caching discounts. Bold indicates the better figure where one is objectively better. Values we could not confirm from the provider are shown as “Not verified” rather than estimated.

Benchmark receipts

Where each score comes from, and how far it can be compared across models.

  • 2026-09-26
    Artificial Analysis GPQA Diamond (independent; replaces Mistral's non-comparable base-model 5-shot 43.9)

    Graduate-level science reasoning: multiple-choice questions written by domain PhDs.

    Comparable with caveatSmall question pool: differences under ~2 points are within run-to-run noise. Chain-of-thought vs direct answering must match to compare. Saturated: frontier models score ~93–96% and Artificial Analysis dropped it from its Intelligence Index in v4.3 — use Humanity's Last Exam for hard reasoning.

  • 2026-09-26
    Artificial Analysis Terminal-Bench 4.0 (independent AA run, part of Intelligence Index v4.3.2)

    Agentic terminal work: long multi-step tasks executed in a sandboxed shell environment.

    Comparable with caveatNOT comparable with Terminal-Bench 2.x or 3.0 — 4.0 uses a new, non-overlapping task set. Within 4.0, scores from different harnesses (tbench.ai agent entries vs Artificial Analysis runs) are not interchangeable.

  • 2026-09-26
    Artificial Analysis Humanity's Last Exam (independent, 2,158 text-only questions)

    Frontier-knowledge ceiling: extremely hard multi-domain questions written to be near-impossible without deep expertise.

    Comparable with caveatSubset/tool configurations (text-only vs with-tools) differ between vendors and materially change scores; must match configuration to compare.

  • 2026-09-26
    Artificial Analysis

    Composite index blending reasoning, knowledge, and coding evals into one 0–100 score.

    Comparable with caveatOnly same-version scores are comparable. v4.3.2 was rebaselined (the top score fell from 66 on v4.1.1 to ~58), so v4.1.1 figures must not be compared with v4.3.2 figures — check measuredAt.

  • 2026-09-22
    Anthropic — Claude Opus 5.5 announcement (vendor; conflicts with AA's independent 59.6 — harness difference preserved)

    Agentic terminal work: long multi-step tasks executed in a sandboxed shell environment.

    Comparable with caveatNOT comparable with Terminal-Bench 2.x or 3.0 — 4.0 uses a new, non-overlapping task set. Within 4.0, scores from different harnesses (tbench.ai agent entries vs Artificial Analysis runs) are not interchangeable.

Pricing tiers

Claude Opus 5.5: $4/$20 per MTok, no long-context surcharge. Cache reads $0.20; 5-minute cache writes $5, 1-hour writes $8. Batch $2/$10; Fast mode $8/$40. Batches API allows 300K output with the output-300k-2026-03-24 beta header. Knowledge cutoff Jun 2026; retirement not before 2027-09-22.

Mistral Large 3: Mistral first-party API $0.50/$1.50 per MTok; cached input $0.05/MTok. Open weights (Apache 2.0), EU-hosted.

FrontierRecord checked September 26, 2026

Claude Opus 5.5

Claude Opus 5.5 is Anthropic's default model for agentic coding and knowledge work — Anthropic says it performs near Fable 5.1 on most work at about 40% lower running cost than Opus 5, and it leads the Artificial Analysis Intelligence Index v4.3.2.

Best for

  • Complex agentic coding
  • Enterprise knowledge work
  • Default frontier model

Watch out

Breaking changes from Opus 5: adaptive thinking cannot be disabled (effort runs low to max, default medium) and forced tool use returns an error. Verbose at max effort, so cap output on cost-sensitive routes.

FrontierOpen weightsRecord checked September 26, 2026

Mistral Large 3

Mistral Large 3 is Mistral's December 2025 open-weight (Apache 2.0) 675B/41B sparse MoE with a 262K context at $0.50/$1.50 — Mistral now features Medium 3.5 as its flagship.

Best for

  • Open-weight deployments
  • Multimodal EU-hosted inference
  • Balanced frontier work

Watch out

No longer Mistral's featured flagship (Medium 3.5 is) and far behind it on the Artificial Analysis index; max output is not published. Verify multimodal support and EU data residency on your endpoint.

When the cheaper one wins

Mistral Large 3 is cheaper on output at $1.50 per million tokens against $20 for Claude Opus 5.5 — about 13×. Use the cheaper tier for classification, extraction, summarisation, and any task where the expensive model’s extra score does not change the accepted output. The expensive one only pays if your hardest task actually fails on the cheap tier. These are standard-tier API rates, excluding batch and cache discounts.

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Evidence confidence: High

How strong and complete the evidence behind this comparison is — not a prediction of which model is better.

  • Pricing verified on both sides — Input and output rates are verified for both models.
  • 2/5 core specs verified on both sides — Not published for at least one side: max output, parameter count, reasoning levels.
  • 1 shared named benchmark with differing scores — Measured on: Artificial Analysis Intelligence Index.
  • Verified within the last 90 days — Newest catalog check was 2 days ago.
  • Both models carry source citations — Each side has at least two catalog sources on record.

Source receipts

Each catalog figure was checked against the provider or an independent second source on the date shown.

Related comparisons

Diving deeper on one model? Claude Opus 5.5 · Mistral Large 3

Common questions

Claude Opus 5.5 vs Mistral Large 3

Answered from the verified figures on this page rather than general guidance.

Is Claude Opus 5.5 or Mistral Large 3 cheaper for input?
Mistral Large 3 is cheaper at $0.50 per million input tokens, against $4 for Claude Opus 5.5 — roughly 8.0× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; Claude Opus 5.5 has tiered pricing: $4/$20 per MTok, no long-context surcharge. Cache reads $0.20; 5-minute cache writes $5, 1-hour writes $8. Batch $2/$10; Fast mode $8/$40. Batches API allows 300K output with the output-300k-2026-03-24 beta header. Knowledge cutoff Jun 2026; retirement not before 2027-09-22. Mistral Large 3 has tiered pricing: Mistral first-party API $0.50/$1.50 per MTok; cached input $0.05/MTok. Open weights (Apache 2.0), EU-hosted.
Is Claude Opus 5.5 or Mistral Large 3 cheaper for output?
Mistral Large 3 is cheaper at $1.50 per million output tokens, against $20 for Claude Opus 5.5 — roughly 13× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; Claude Opus 5.5 has tiered pricing: $4/$20 per MTok, no long-context surcharge. Cache reads $0.20; 5-minute cache writes $5, 1-hour writes $8. Batch $2/$10; Fast mode $8/$40. Batches API allows 300K output with the output-300k-2026-03-24 beta header. Knowledge cutoff Jun 2026; retirement not before 2027-09-22. Mistral Large 3 has tiered pricing: Mistral first-party API $0.50/$1.50 per MTok; cached input $0.05/MTok. Open weights (Apache 2.0), EU-hosted.
Which has the larger context window, Claude Opus 5.5 or Mistral Large 3?
Claude Opus 5.5 accepts 1M tokens against 262K for Mistral Large 3. This only matters if you routinely send very long documents or large codebases.
Should I use Claude Opus 5.5 or Mistral Large 3?
Both sit in the frontier tier, so the choice usually comes down to price and context rather than capability. Claude Opus 5.5 suits complex agentic coding; Mistral Large 3 suits open-weight deployments.
Can I self-host Claude Opus 5.5 or Mistral Large 3?
Mistral Large 3 publishes open weights, but self-hosting and third-party provider access depend on the licence, hardware, serving support, and availability. Claude Opus 5.5 is a closed model whose supported access paths are controlled by its provider.

Next step

Choosing between them

The verified figures that separate this pair, computed from the catalog rather than restated boilerplate.

  • Input price: Mistral Large 3 costs $0.50 per 1M tokens versus $4 for Claude Opus 5.5 — a 8x difference at the headline tier.
  • Context: Claude Opus 5.5 takes 1M against 262K for Mistral Large 3 — only decisive if your prompts approach the smaller window.
  • Measured capability: Claude Opus 5.5 leads Artificial Analysis Intelligence Index 57.6 to 9.3 (measured 2026-09-26).
  • Deployment: Mistral Large 3 publishes weights you can self-host; the other is API-only.
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