// head_to_head
Aion-2.0 vs Claude Fable 5.1
Published LiveBench scores across all seven categories, live list pricing, context windows, and the measured cost of a point of capability — for both models, side by side.
Aion-2.0 is the cheaper of the two; neither can be ranked on quality here.
Aion-2.0 does not have a published LiveBench run, so this comparison covers price, context and declared capabilities only. A missing score means "not evaluated", not "worse" — the right way to separate these two is an eval on your own workload.
aion-labs
Aion-2.0
- Blended / 1M
- $1.00
- Context
- 131K
- Released
- Feb 23, 2026
- Overall score
- Not evaluated
anthropic
Claude Fable 5.1
- Blended / 1M
- $20.00
- Context
- 1M
- Released
- Sep 1, 2026
- Overall score
- 83.4
Specs and pricing
| Metric | Aion-2.0 | Claude Fable 5.1 |
|---|---|---|
| LiveBench overall Mean of the seven LiveBench category scores, 0–100. Higher is better. | — | 83.4 |
| Cost per point Measured benchmark spend divided by overall score — dollars per point of capability. | — | $0.6668 |
| Blended price / 1M 3:1 input:output mix, the usual shape of production traffic. | $1.00win | $20.00 |
| Input price / 1M | $0.800win | $10.00 |
| Output price / 1M | $1.60win | $50.00 |
| Cached input / 1M Price of an input token served from the prompt cache, where the provider publishes one. | $0.200win | $0.250 |
| Context window | 131K | 1Mwin |
| Max output tokens | 33K | 128Kwin |
Benchmarks by category
An overall score averages away the thing you probably care about. These are the seven LiveBench categories scored separately — Aion-2.0 on top, Claude Fable 5.1 below, both out of 100.
What each one costs to run
Per-token prices are hard to feel. These are monthly list costs for both models across five workload shapes, using each provider's published cached-input rate where there is one.
| Workload | Aion-2.0 | Claude Fable 5.1 |
|---|---|---|
| Support chatbot 1.2K in / 400 out × 200K requests | $276.80/mo | $5,698/mo |
| RAG assistant 8K in / 600 out × 100K requests | $496.00/mo | $7,100/mo |
| Coding agent 40K in / 4K out × 20K requests | $432.00/mo | $6,540/mo |
| Document extraction 20K in / 1.5K out × 50K requests | $890.00/mo | $13,263/mo |
| Bulk classification 500 in / 20 out × 5M requests | $1,860/mo | $25,125/mo |
Which should you pick?
You need to fit large documents in one call
Claude Fable 5.1
Wider context window — 1M against 131K.
You are cost-constrained
Aion-2.0
Cheaper on blended list price at $1.00 per million tokens.
Aion-2.0 vs Claude Fable 5.1 FAQ
Which is better, Aion-2.0 or Claude Fable 5.1?
Aion-2.0 is the cheaper of the two; neither can be ranked on quality here. Aion-2.0 does not have a published LiveBench run, so this comparison covers price, context and declared capabilities only. A missing score means "not evaluated", not "worse" — the right way to separate these two is an eval on your own workload.
Is Aion-2.0 cheaper than Claude Fable 5.1?
Aion-2.0 is cheaper. On a 3:1 input:output blend, Aion-2.0 lists at $1.00 per million tokens and Claude Fable 5.1 at $20.00 — Aion-2.0 is 20× cheaper. Input and output are priced separately — Aion-2.0 charges $0.800 in and $1.60 out, Claude Fable 5.1 charges $10.00 and $50.00 — so the model that looks cheaper flips depending on how output-heavy your workload is.
Does Aion-2.0 or Claude Fable 5.1 have a bigger context window?
Claude Fable 5.1 has the larger context window: 131K for Aion-2.0 against 1M for Claude Fable 5.1. Note that a window you can fill is not a window you should fill — retrieval quality usually degrades well before the limit, and you pay for every token you put in it.
Do Aion-2.0 and Claude Fable 5.1 support prompt caching?
Both publish a cached-input rate: $0.200 per million for Aion-2.0 and $0.250 for Claude Fable 5.1, against full input rates of $0.800 and $10.00. On a workload with a long stable prefix — a system prompt, a tool schema, a retrieved corpus — that changes the economics more than the headline price does.
Related comparisons
How these numbers are produced
- Price — provider list price from OpenRouter, refreshed every 15 minutes. “Blended” is a 3:1 input:output mix.
- Scores — LiveBench release 2026-06-25, using their own category map. Each model shows its strongest published run. A blank means “not evaluated”, never “bad”.
- Cost per point — the measured dollars LiveBench spent on the run, divided by the score it earned.
- “Win” — awarded only past a threshold: one full point on a benchmark score, 10% on a price, 25% on a context window. Anything tighter reports as a tie, because effort settings alone move a LiveBench score by more than that.
Published benchmarks rank models on someone else's tasks. Before committing, see LLM & agent evaluation for building an eval on your own.