Cheaper overall
Claude Fable 5.1
70% lower blended rate
Higher benchmark scores
GPT-5.4 Pro
leads on 1 of 1 figures
Bigger context window
GPT-5.4 Pro
1,050,000 vs 1,000,000 tokens
Where each one wins
Claude Fable 5.1
- Cheaper input tokens $10.00 vs $30.00, 67% less
- Cheaper output tokens $50.00 vs $180.00, 72% less
- Cheaper on all four workloads
GPT-5.4 Pro
- Larger context window 1,050,000 tokens
- Higher physics research reasoning (CritPt) 30 vs 29.7
- Offers Flex pricing not listed for Claude Fable 5.1
What four workloads cost
One run, and the same run a thousand times.
The gap opens on long prompts: Claude Fable 5.1 costs $4.15 against $24.81, a difference of $20,660.00 over a thousand runs.
| Workload | Claude Fable 5.1 | GPT-5.4 Pro | ×1,000 | Difference |
|---|---|---|---|---|
| Chat turn 1,000 in / 500 out | $0.0350 | $0.1200 | $35.00 / $120.00 | Claude Fable 5.1 is 71% cheaper |
| RAG answer 10,000 in / 800 out | $0.1400 | $0.4440 | $140.00 / $444.00 | Claude Fable 5.1 is 68% cheaper |
| Agent loop 32,000 in / 700 out × 20 calls | $1.25 | $21.72 | $1,250.00 / $21,720.00 | Claude Fable 5.1 is 94% cheaper |
| Long document 400,000 in / 3,000 out | $4.15 | $24.81 | $4,150.00 / $24,810.00 | Claude Fable 5.1 is 83% cheaper |
One of these models lists no cached-input price, so its cached tokens are charged at the full input rate.
Price per 1M tokens
Above 272,000 input tokens the rates change, and the new rate applies to the whole request, not just the tokens past that point: GPT-5.4 Pro's input goes from $30.00 to $60.00. It does not change which of the two is cheaper.
| Context band | Price | Claude Fable 5.1 | GPT-5.4 Pro | Difference |
|---|---|---|---|---|
| Prompts up to 272,000 tokens | Input | $10.00 | $30.00 | Claude Fable 5.1 is 67% cheaper |
| Prompts up to 272,000 tokens | Cached input | $0.25 | — | |
| Prompts up to 272,000 tokens | Output | $50.00 | $180.00 | Claude Fable 5.1 is 72% cheaper |
| Prompts over 272,000 tokens | Input | $10.00 | $60.00 | Claude Fable 5.1 is 83% cheaper |
| Prompts over 272,000 tokens | Cached input | $0.25 | — | |
| Prompts over 272,000 tokens | Output | $50.00 | $270.00 | Claude Fable 5.1 is 81% cheaper |
Blended: Claude Fable 5.1 $20.00, GPT-5.4 Pro $67.50 per 1M — one rate at 3:1 input to output, for comparing two models at a glance.
Claude Fable 5.1 priced by Anthropic, GPT-5.4 Pro by OpenAI. Standard tier, pay-as-you-go.
Other pricing tiers
Both models offer Batch, worth up to 50% off their standard rates, and the cheaper model is the same one on every tier — so the tier you buy changes the bill rather than the choice. Only GPT-5.4 Pro lists Flex, at up to 50% off its own standard rate; Claude Fable 5.1 does not offer it.
Every tier either model sells is here, so this is the whole price sheet. A saving is measured against that model's own standard rate — how we read tiers.
| Tier | Claude Fable 5.1 | GPT-5.4 Pro | Cheaper |
|---|---|---|---|
| Batch | $5.00 in / $25.00 out 50% off Standard | $15.00 in / $90.00 out 50% off Standard | Claude Fable 5.1 |
| Flex only on GPT-5.4 Pro | Not offered | $15.00 in / $90.00 out 50% off Standard | — |
Benchmarks
GPT-5.4 Pro is ahead on the one figure both models report, physics research reasoning (CritPt), by 0.3 points.
Physics research reasoning
CritPt — Unpublished physics research reasoning problems
GPT-5.4 Pro ahead by 0.3
Each figure is that model's best published run, with the effort level named beside it — where these scores come from.
Specifications
GPT-5.4 Pro holds 50,000 more input tokens in one request.
| Specification | Claude Fable 5.1 | GPT-5.4 Pro |
|---|---|---|
| Context window | 1,000,000 tokens | 1,050,000 tokens |
| Max output | 128,000 tokens | 128,000 tokens |
| Takes in | Text, image, file | Text, image, file |
| Puts out | Text | Text |
| Knowledge cutoff | 30 Jun 2026 | 31 Aug 2025 |
| Released | 1 Sep 2026 | 5 Mar 2026 |
| Status | Active | Active |
| Sold by | Anthropic | OpenAI |
FAQs
- Is Claude Fable 5.1 cheaper than GPT-5.4 Pro?
- Yes. A 1,000-token prompt with a 500-token reply costs $0.0350 on Claude Fable 5.1 and $0.1200 on GPT-5.4 Pro, and the same model is cheaper on every workload on this page.
- How much do Claude Fable 5.1 and GPT-5.4 Pro cost per 1M tokens?
- Claude Fable 5.1 costs $10.00 for input and $50.00 for output. GPT-5.4 Pro costs $30.00 and $180.00. Standard pay-as-you-go rates, as of 1 Sep 2026.
- Which is better, Claude Fable 5.1 or GPT-5.4 Pro?
- On published benchmarks, GPT-5.4 Pro. It leads on 1 of the 1 figures both models report, including physics research reasoning (CritPt), where it scores 30 against 29.7.
- Is Batch pricing cheaper for Claude Fable 5.1 or GPT-5.4 Pro?
- Batch input costs $5.00 on Claude Fable 5.1 and $15.00 on GPT-5.4 Pro, 50% below the standard rate on both.
- Does Claude Fable 5.1 or GPT-5.4 Pro have a bigger context window?
- GPT-5.4 Pro, at 1,050,000 tokens against 1,000,000. That is 50,000 more input tokens in a single request.