Neither wins outright: Anthropic: Claude Fable 5.1 (batch) is the pick when cost matters at scale, OpenAI: GPT-5 Pro when you need seed (reproducible sampling).
| Spec | Anthropic: Claude Fable 5.1 (batch) | OpenAI: GPT-5 Pro |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Input price (per 1M tokens) | $5.00 | $15.00 |
| Output price (per 1M tokens) | $25.00 | $120 |
| Blended price (3:1 input/output) | $10.00 | $41.25 |
| Cheaper than … of all models we track | 5% | 1% |
| Context window | 1M tokens (~1,500 pages) | 400K tokens (~600 pages) |
| Larger context than … of all models | 69% | 63% |
| Max output per response | 128K tokens (~96,000 words) | 128K tokens (~96,000 words) |
| Input types | text, image, file | image, text, file |
| Output types | text | text |
| Free variant | No | No |
| Listed since | 2026-09-01 | 2025-10-06 |
Monthly cost at list price for five common workloads. Token counts per unit are stated so you can scale them to your own traffic. A workload that does not fit a model's context window is marked rather than priced.
| Workload (per month) | Anthropic: Claude Fable 5.1 (batch) | OpenAI: GPT-5 Pro | Difference |
|---|---|---|---|
| Customer-support chatbot 50,000 conversations — each a 6-turn conversation (1,500 in / 400 out tokens) | $875 | $3,525 | Anthropic: Claude Fable 5.1 (batch) saves $2,650 |
| RAG search over documents 20,000 questions — each a question answered from ~8 retrieved passages (6,000 in / 500 out tokens) | $850 | $3,000 | Anthropic: Claude Fable 5.1 (batch) saves $2,150 |
| Coding / tool-using agent 2,000 tasks — each a multi-step task with tool calls and file context (60,000 in / 6,000 out tokens) | $900 | $3,240 | Anthropic: Claude Fable 5.1 (batch) saves $2,340 |
| Batch summarisation 10,000 documents — each a 6,000-word report summarised to a page (8,000 in / 600 out tokens) | $550 | $1,920 | Anthropic: Claude Fable 5.1 (batch) saves $1,370 |
| Long-document analysis 500 documents — each a 150-page contract or codebase read in one pass (100,000 in / 2,000 out tokens) | $275 | $870 | Anthropic: Claude Fable 5.1 (batch) saves $595 |
| Capability | Anthropic: Claude Fable 5.1 (batch) | OpenAI: GPT-5 Pro | What it lets you do |
|---|---|---|---|
| Tool / function calling | ✓ Yes | ✓ Yes | call your APIs and run agent loops |
| Structured output (JSON schema) | ✓ Yes | ✓ Yes | return JSON that validates against your schema |
| Reasoning / thinking mode | ✓ Yes | ✓ Yes | spend extra tokens thinking before answering hard problems |
| Image input | ✓ Yes | ✓ Yes | read screenshots, charts and scanned pages |
| Audio input | — | — | take speech or audio directly |
| File / PDF input | ✓ Yes | ✓ Yes | accept documents without your own parsing step |
| Image output | — | — | generate images, not just text |
| Built-in web search | ✓ Yes | ✓ Yes | answer from live web results |
| Seed (reproducible sampling) | — | ✓ Yes | repeat a generation for tests and evals |
| Log-probabilities | — | — | read token confidence for classification and scoring |
From each model's published parameters and input/output types. “—” means not advertised, not proven absent.
Neither wins outright: Anthropic: Claude Fable 5.1 (batch) is the pick when cost matters at scale, OpenAI: GPT-5 Pro when you need seed (reproducible sampling). In short: Anthropic: Claude Fable 5.1 (batch) when cost matters at scale, you need to fit long inputs in one request, you want the newer model; OpenAI: GPT-5 Pro when you need seed (reproducible sampling).
Anthropic: Claude Fable 5.1 (batch) is cheaper: $10.00 vs $41.25 per 1M tokens at a typical 3:1 input/output mix, 76% less. For 50,000 support conversations a month that is $875 against $3,525.
Anthropic: Claude Fable 5.1 (batch) costs $5.00 per 1M input tokens and $25.00 per 1M output tokens; OpenAI: GPT-5 Pro costs $15.00 input and $120 output. Output tokens are billed separately, so long answers shift the gap.
Anthropic: Claude Fable 5.1 (batch): 1M tokens, about 1,500 pages, against 400K (about 600 pages) for OpenAI: GPT-5 Pro.
Tool calling — Anthropic: Claude Fable 5.1 (batch): yes, OpenAI: GPT-5 Pro: yes. JSON-schema structured output — Anthropic: Claude Fable 5.1 (batch): yes, OpenAI: GPT-5 Pro: yes.
Yes, both accept image input.
No free variant is listed for either; both are pay-per-token.
Anthropic: Claude Fable 5.1 (batch) can write up to 128K tokens (about 96,000 words) per response; OpenAI: GPT-5 Pro up to 128K (about 96,000 words).
Anthropic: Claude Fable 5.1 (batch) was listed on 2026-09-01; OpenAI: GPT-5 Pro on 2025-10-06.
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