Claude Fable 5 vs GPT-5.5 Instant
Pricing, benchmarks, and use case comparison
Quick take
- •Claude Fable 5 is meaningfully stronger at coding (99 vs 78 on our capability index).
- •GPT-5.5 Instant is meaningfully stronger at speed (92 vs 55).
- •GPT-5.5 Instant is 50% cheaper on input tokens, which compounds fast on high-volume or agentic workloads.
Specs comparison
| Claude Fable 5 | GPT-5.5 Instant | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Type | Closed source | Closed source |
| Context window | 1M | ✓1050000 |
| Input / 1M tokens | $10.00 | ✓5.00 |
| Output / 1M tokens | $50.00 | 30.00 |
| Release date | 2026-06 | 2026-05 |
Benchmarks
| Benchmark | Claude Fable 5 | GPT-5.5 Instant |
|---|---|---|
| SWE-bench Verified | 95.0% | - |
| Terminal-Bench 2.1 | 88.0% | - |
| GPQA Diamond | 92.6% | - |
| SWE-bench Pro | 80.3% | - |
| AIME 2025 | - | 81.2 |
| Terminal-Bench 2.0 | - | 82.7 |
| FrontierMath Tier 1–3 | - | 51.7 |
Scores sourced from official provider release posts and independent benchmark aggregators.
Which should you choose?
Choose Claude Fable 5 if...
- →You need the absolute highest capability Anthropic offers for hard tasks
- →You run long, complex autonomous agents where quality compounds over many steps
- →You do frontier-level engineering, research, or analytics and cost is secondary
- →You want maximum accuracy on the toughest coding and reasoning benchmarks
Choose GPT-5.5 Instant if...
- →Interactive chat and everyday assistant tasks where responsiveness matters most
- →High-volume, latency-sensitive workloads that do not need deep reasoning
- →General questions, drafting, and summarization at speed