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Model comparison

Claude Fable 5 vs Upstage Solar Pro 4

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

Catalog record checked September 3, 2026Individual provider fields may changeEvidence confidence: High — see receipts below

Anthropic

Claude Fable 5

Frontier

vs

Upstage

Upstage Solar Pro 4

Frontier

AI model capability comparison
SpecificationClaude Fable 5Upstage Solar Pro 4
ProviderAnthropicUpstage
TierFrontierFrontier
Context windowWinner: 1M524K
Max output128KNot verifiedUnverified
Input / 1M tokens$10Winner: $0.30
Output / 1M tokens$50Winner: $1.20
WeightsClosedClosed
ParametersNot disclosedUnverifiedNot disclosedUnverified
Reasoning levelsadaptivelow, medium, high
Modalitiestext, imagetext
API model idclaude-fable-5solar-pro-4
ReleasedJune 9, 2026August 10, 2026
Artificial Analysis Intelligence Index (2026-08-14)Winner: 6250

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

  • 2026-08-14: Artificial AnalysisComposite index blending reasoning, knowledge, and coding evals into one 0–100 score. Comparability: directly comparable — AA occasionally rebaselines the index scale between snapshots — a score captured on one date is only comparable to same-snapshot scores (check measuredAt).

Pricing tiers: Claude Fable 5: Standard $10/$50 per MTok; cache reads 10% of base input. Sibling Claude Mythos 5 is invite-only cyber-defense. Access briefly suspended 2026-06-12, redeployed 2026-07-01. · Upstage Solar Pro 4: List $0.30/$1.20 per MTok; live promo rate is $0.03/$0.12 (90% off through 2026-09-10). Closed API. 524K context.

FrontierRecord checked September 3, 2026

Claude Fable 5

Claude Fable 5 is Anthropic's next-generation intelligence model for long-running agents, topped LiveBench until the 5.1 refresh.

Best for

  • Long-running agents
  • Frontier reasoning
  • Enterprise work

Watch out

Most expensive Anthropic tier at $10/$50; verify the cost is justified by the task.

FrontierRecord checked September 2, 2026

Upstage Solar Pro 4

Solar Pro 4 is Upstage's closed flagship with a 524K context at a low launch price.

Best for

  • Long-context
  • Cost-sensitive API
  • Korean + English

Watch out

Closed API; promo pricing may end.

When the cheaper one wins

Upstage Solar Pro 4 is cheaper on output at $1.20 per million tokens against $50 for Claude Fable 5 — about 42×. 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.
  • 3/5 core specs verified on both sides — Not published for at least one side: max output, parameter count.
  • 1 shared named benchmark with differing scores — Measured on: Artificial Analysis Intelligence Index.
  • Verified within the last 90 days — Newest catalog check was 8 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 Fable 5 · Upstage Solar Pro 4

Common questions

Claude Fable 5 vs Upstage Solar Pro 4

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

Is Claude Fable 5 or Upstage Solar Pro 4 cheaper for input?

Upstage Solar Pro 4 is cheaper at $0.30 per million input tokens, against $10 for Claude Fable 5 — roughly 33× 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 Fable 5 has tiered pricing: Standard $10/$50 per MTok; cache reads 10% of base input. Sibling Claude Mythos 5 is invite-only cyber-defense. Access briefly suspended 2026-06-12, redeployed 2026-07-01. Upstage Solar Pro 4 has tiered pricing: List $0.30/$1.20 per MTok; live promo rate is $0.03/$0.12 (90% off through 2026-09-10). Closed API. 524K context.

Is Claude Fable 5 or Upstage Solar Pro 4 cheaper for output?

Upstage Solar Pro 4 is cheaper at $1.20 per million output tokens, against $50 for Claude Fable 5 — roughly 42× 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 Fable 5 has tiered pricing: Standard $10/$50 per MTok; cache reads 10% of base input. Sibling Claude Mythos 5 is invite-only cyber-defense. Access briefly suspended 2026-06-12, redeployed 2026-07-01. Upstage Solar Pro 4 has tiered pricing: List $0.30/$1.20 per MTok; live promo rate is $0.03/$0.12 (90% off through 2026-09-10). Closed API. 524K context.

Which has the larger context window, Claude Fable 5 or Upstage Solar Pro 4?

Claude Fable 5 accepts 1M tokens against 524K for Upstage Solar Pro 4. This only matters if you routinely send very long documents or large codebases.

Do Claude Fable 5 and Upstage Solar Pro 4 support the same reasoning levels?

Claude Fable 5 exposes adaptive, while Upstage Solar Pro 4 exposes low, medium, high.

Should I use Claude Fable 5 or Upstage Solar Pro 4?

Both sit in the frontier tier, so the choice usually comes down to price and context rather than capability. Claude Fable 5 suits long-running agents; Upstage Solar Pro 4 suits long-context.

Next step

Choosing between them

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

  • Input price: Upstage Solar Pro 4 costs $0.30 per 1M tokens versus $10 for Claude Fable 5 — a 33.3x difference at the headline tier.
  • Context: Claude Fable 5 takes 1M against 524K for Upstage Solar Pro 4 — only decisive if your prompts approach the smaller window.
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