Claude Fable 5 vs GPT-5.5
The frontier matchup of mid-2026: Anthropic's brand-new Fable 5 against OpenAI's GPT-5.5. Both top their vendors' lineups; here is how they actually compare on the boards and the bill.
Claude Fable 5 is the most capable coding model we track, full stop: 72.9% on CursorBench 3.1 at max effort and 64.9 on the Artificial Analysis Intelligence Index, both the best results on our boards. GPT-5.5 sits at 64.3% and 58.9 respectively.
GPT-5.5 answers back on price: $5 per million input tokens versus Fable 5's $10, and $30 output versus $50. For high-volume agent work that gap compounds fast, and GPT-5.5's token efficiency is strong.
The practical split: Fable 5 when the task is hard enough that failure costs more than tokens; GPT-5.5 as the high-end workhorse. Both carry 1M token context windows, so neither wins on fitting your codebase.
Prices and context are synced from live provider listings. Deep dives: Claude Fable 5 and GPT-5.5.
Best published configuration per model. Every config and source is on the benchmark leaderboards.
Every published configuration for Claude Fable 5 and GPT-5.5 on the benchmarks they share, charted side by side. Only these two models are plotted.
SWE-bench Verified
The most-cited agentic coding benchmark: can a model fix a real GitHub issue in a real repository? 500 human-validated tasks, scored by the repo's own tests. Higher is better.
CursorBench 3.1
Ambiguous, multi-file tasks from real Cursor sessions that test codebase understanding, bugfinding, planning, and code review.
FrontierCode Main
Cognition's test of whether a model writes code maintainers would actually merge, not just code that passes tests. Main is the 100 hardest of 150 tasks. Higher is better.
OSWorld-Verified
The standard computer-use benchmark: agents complete real desktop tasks in a live Ubuntu VM from screenshots, mouse and keyboard, scored by execution-based checks. Higher is better.
BrowseComp
OpenAI's hard web-browsing benchmark: 1,266 questions whose answers are hard to find but easy to verify, requiring persistent multi-step browsing. Higher is better.
Artificial Analysis Intelligence Index
The most-cited composite intelligence score: a 0–100 index combining knowledge, reasoning, math, coding, and agentic evaluations (GPQA Diamond, HLE, IFBench, SciCode, Terminal-Bench Hard, τ²-Bench, and more). Higher is better.
Design Arena
A crowdsourced Elo arena for AI-generated design and frontend code. Models go head to head on the same prompt (websites, UI components, games, mobile apps, SVG), and human votes set the rating. Higher Elo is better.
Is Claude Fable 5 better than GPT-5.5?
On the benchmarks we track, yes: Fable 5 leads CursorBench 3.1 (72.9% versus 64.3% at each model's best effort setting) and the Artificial Analysis Intelligence Index (64.9 versus 58.9). GPT-5.5 counters on price at half the per-token cost, so the right pick depends on how hard your tasks are.
Is Claude Fable 5 worth double the price of GPT-5.5?
For hard, multi-step engineering where a failed run wastes an hour, usually yes: the capability gap is the largest at the top of our boards. For everyday coding, GPT-5.5 (or cheaper models like GPT-5.4 and Claude Sonnet 4.6) deliver most of the value at a fraction of the cost. Route by task difficulty rather than picking one.
Which agents can use Fable 5 and GPT-5.5?
Fable 5 runs in Claude Code natively and anywhere the Anthropic API plugs in, including Hermes and OpenClaw. GPT-5.5 runs in Codex on a ChatGPT plan, and through the OpenAI API or OpenRouter in other agents. Our best-models rankings per agent show current recommendations.
Type
Model comparisonClaude Fable 5
Model pageGPT-5.5
Model pageUpdated
June 2026