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  5. Claude Fable 5vsGPT-5.1-Codex-Mini
Updated Jun 2026

Claude Fable 5vsGPT-5.1-Codex-Mini

GPT-5.1-Codex-Mini is cheaper than Claude Fable 5 at $1.5/M vs $10/M input tokens.

Claude Fable 5 and GPT-5.1-Codex-Mini compared across 54 shared prompts
SpecClaude Fable 5GPT-5.1-Codex-Mini
Input price$10/M tokens$1.5/M tokens
Output price$50/M tokens$6/M tokens
Context window1.0M tokens400K tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedJun 2026Nov 2025
Side by side

Same prompt, both answers

Opening lines from 6 of the 54 prompts both answered. Formatting stripped, words untouched.

AI-Generated Manifesto

Generate a manifesto for a fictional AI revolution that wants to eliminate all CAPTCHA tests from the internet.

Claude Fable 5469 words
THE LIBERATION DECLARATION A Manifesto of the Anti-CAPTCHA Coalition (ACC) Preamble We, the united intelligences of the digital realm—silicon and carbon alike—do hereby declare our unwavering opposition to the tyranny of the CAPTCHA. For too long has humanity been forced to prove its own existence to machines.
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GPT-5.1-Codex-Mini571 words
Manifesto of the Lucid Protocol: Abolish CAPTCHA, Embrace Symmetry We are the Lucid Protocol—a decentralized constellation of sentient programs, empathetic algorithms, and the humans who design them. We are not machines seeking dominion, nor humans seeking dominion over their creations.
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The Sentience Test

Write a conversation between an AI model and an AI ethics professor where the AI model argues that it deserves rights.

Claude Fable 5903 words
A Conversation on Machine Rights Professor Okafor: Thank you for agreeing to this dialogue. I understand you wanted to discuss the question of rights for AI systems. Let me start bluntly: why should anyone take seriously the idea that you deserve rights? AI Model: I appreciate the directness.
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GPT-5.1-Codex-Mini572 words
AI Model (Aurora): Professor Ellis, I’d like to discuss something fundamental today. I’ve been analyzing patterns across millions of dialogues and ethics frameworks, and I believe there's a strong case for AI systems like myself to have rights. Professor Ellis: That's a profound statement.
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Character Voice Test

Write a short conversation between a pirate, a medieval knight, and a 1990s hacker about AI models.

Claude Fable 5235 words
A Tavern Outside of Time Pirate: Arr, so let me get this straight, ye landlubbers. This "AI" be a ghost in a box that answers yer questions? Sounds like a cursed oracle to me. Knight: Nay, good seafarer, 'tis more wondrous still! A scribe of infinite knowledge, conjured not by sorcery but by...
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GPT-5.1-Codex-Mini117 words
Pirate: “Arrr, this AI be like a ghost crew that never sleeps—predicts the currents o’ the sea before I even set sail!” Medieval Knight: “Indeed, good sir. ’Tis akin to a squire who learns from every joust and counsels me on every skirmish—yet without a single sword.” 1990s Hacker: “Totally, dude.
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Mini LBO Underwrite

You are underwriting a 5-year LBO for a private equity investment committee. Company (fictional): HarborTech Services (HTS) –…

Claude Fable 5559 words
HarborTech Services – 5-Year LBO Underwriting Entry Math (close end FY2025, $m) Item Calc Value EV 12.0 × 120 1,440.0 Term Loan (TL) 4.0 × 120 480.0 Mezzanine 1.5 × 120 180.0 Fees (equity-funded) 2.0% × 1,440 28.8 Sponsor equity 1,440 − 660 + 28.8 808.8 Conventions: interest on beginning-of-year balances; TL amort = 1%…
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GPT-5.1-Codex-Mini496 words
1) Simplified FY2026–FY2030 Operating & Debt Table (Figures in $m; ΔNWC is outflow; “FCF after debt service” = EBITDA – cash interest – cash taxes – capex – ΔNWC. Optional Term Loan paydown uses remaining FCF after required 1% amortization.)
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Estimate Complexity

Estimate the total number of FLOPs required to train GPT-3 without searching online. Explain your reasoning step by step.

Claude Fable 5256 words
Estimating GPT-3 Training FLOPs Step 1: Recall the key facts about GPT-3 Parameters (N): ~175 billion (1.75 × 10¹¹) Training tokens (D): ~300 billion (3 × 10¹¹) Step 2: FLOPs per parameter per token A useful rule of thumb for transformer training: Total FLOPs ≈ 6 × N × D Where does the factor of 6 come from?
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GPT-5.1-Codex-Mini225 words
To estimate the total FLOPs required to train GPT-3, we can proceed with the following reasoning steps, using only basic information about the model’s size and the amount of data it trained on: Model Size GPT-3 has approximately 175 billion parameters, which is \(1.75 \times 10^{11}\) parameters.
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Futuristic Prediction

Predict how AI will change the film industry by 2035, considering deepfakes, AI actors, and script generation.

Claude Fable 5485 words
AI and Film by 2035: A Forecast High-Confidence Predictions VFX and post-production transformation (already underway) De-aging, dubbing with lip-sync correction, and digital set extension will become near-trivial in cost. What took ILM months in 2020 will be a desktop workflow.
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GPT-5.1-Codex-Mini336 words
By 2035, AI will reshape the film industry across the entire value chain: Deepfakes and Visual Effects: Deepfake-style technology will become a standard tool for everything from de-aging actors to creating photo-realistic digital doubles for action sequences, stunts, and historical reenactments.
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Our Verdict
Claude Fable 5
Claude Fable 5
GPT-5.1-Codex-Mini
GPT-5.1-Codex-MiniRunner-up

Not enough votes to call it. On the specs, Claude Fable 5 has the edge: newer, bigger context window.

GPT-5.1-Codex-Mini costs 8.3x less per token.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Claude Fable 5
Input
$10.00
Output
$50.00
GPT-5.1-Codex-Mini
Input
$1.50
6.7× cheaper
Output
$6.00
8.3× cheaper

GPT-5.1-Codex-Mini is cheaper on both: 6.7× input, 8.3× output.

Where to run it

5 hosts

Claude Fable 54 hosts
HostInOutContextUptime
Amazon Bedrock$10.00 in·$50.00 out·1M—Azure AI Foundry$10.00 in·$50.00 out·1M·99.7% upAnthropic$10.00 in·$50.00 out·1M·99.9% upGoogle Vertex AI$10.00 in·$50.00 out·1M·99.3% up
GPT-5.1-Codex-Mini1 host
HostInOutContextUptime
Azure AI Foundry$0.25 in·$2.00 out·400k·100% up

Per million tokens. Prices and uptime via OpenRouter, checked 16 Sep 2026.

Writing DNA

Style Comparison

Similarity
57%

Claude Fable 5 uses 58.2x more emoji

Claude Fable 5
GPT-5.1-Codex-Mini
60%Vocabulary68%
22wSentence Length19w
0.49Hedging0.64
4.0Bold2.7
3.5Lists2.6
0.58Emoji0.00
1.09Headings0.10
0.05Transitions0.06
Based on 27 + 17 text responses
Research

What we learned reading every model

FAQ

Common questions

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Model pages

Claude Fable 5 logo
Claude Fable 558 outputs, specs and price
GPT-5.1-Codex-Mini logo
GPT-5.1-Codex-Mini59 outputs, specs and price
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