// head_to_head
Claude Opus 5.5 vs SpaceXAI: Grok 4.20 Multi-Agent
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.
SpaceXAI: Grok 4.20 Multi-Agent is the cheaper of the two; neither can be ranked on quality here.
SpaceXAI: Grok 4.20 Multi-Agent 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.
anthropic
Claude Opus 5.5
- Blended / 1M
- $8.00
- Context
- 1M
- Released
- Sep 22, 2026
- Overall score
- 83.2
x-ai
SpaceXAI: Grok 4.20 Multi-Agent
- Blended / 1M
- $1.56
- Context
- 2M
- Released
- Mar 31, 2026
- Overall score
- Not evaluated
Specs and pricing
| Metric | Claude Opus 5.5 | SpaceXAI: Grok 4.20 Multi-Agent |
|---|---|---|
| LiveBench overall Mean of the seven LiveBench category scores, 0–100. Higher is better. | 83.2 | — |
| Cost per point Measured benchmark spend divided by overall score — dollars per point of capability. | $0.4474 | — |
| Blended price / 1M 3:1 input:output mix, the usual shape of production traffic. | $8.00 | $1.56win |
| Input price / 1M | $4.00 | $1.25win |
| Output price / 1M | $20.00 | $2.50win |
| Cached input / 1M Price of an input token served from the prompt cache, where the provider publishes one. | $0.200 | $0.200 |
| Context window | 1M | 2Mwin |
| Max output tokens | 128K | 1.8Mwin |
Benchmarks by category
An overall score averages away the thing you probably care about. These are the seven LiveBench categories scored separately — Claude Opus 5.5 on top, SpaceXAI: Grok 4.20 Multi-Agent 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 | Claude Opus 5.5 | SpaceXAI: Grok 4.20 Multi-Agent |
|---|---|---|
| Support chatbot 1.2K in / 400 out × 200K requests | $2,286/mo | $424.40/mo |
| RAG assistant 8K in / 600 out × 100K requests | $2,880/mo | $730.00/mo |
| Coding agent 40K in / 4K out × 20K requests | $2,672/mo | $612.00/mo |
| Document extraction 20K in / 1.5K out × 50K requests | $5,310/mo | $1,385/mo |
| Bulk classification 500 in / 20 out × 5M requests | $10,100/mo | $2,850/mo |
Which should you pick?
You need to fit large documents in one call
SpaceXAI: Grok 4.20 Multi-Agent
Wider context window — 2M against 1M.
Claude Opus 5.5 vs SpaceXAI: Grok 4.20 Multi-Agent FAQ
Which is better, Claude Opus 5.5 or SpaceXAI: Grok 4.20 Multi-Agent?
SpaceXAI: Grok 4.20 Multi-Agent is the cheaper of the two; neither can be ranked on quality here. SpaceXAI: Grok 4.20 Multi-Agent 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 Claude Opus 5.5 cheaper than SpaceXAI: Grok 4.20 Multi-Agent?
SpaceXAI: Grok 4.20 Multi-Agent is cheaper. On a 3:1 input:output blend, Claude Opus 5.5 lists at $8.00 per million tokens and SpaceXAI: Grok 4.20 Multi-Agent at $1.56 — SpaceXAI: Grok 4.20 Multi-Agent is 5.1× cheaper. Input and output are priced separately — Claude Opus 5.5 charges $4.00 in and $20.00 out, SpaceXAI: Grok 4.20 Multi-Agent charges $1.25 and $2.50 — so the model that looks cheaper flips depending on how output-heavy your workload is.
Does Claude Opus 5.5 or SpaceXAI: Grok 4.20 Multi-Agent have a bigger context window?
SpaceXAI: Grok 4.20 Multi-Agent has the larger context window: 1M for Claude Opus 5.5 against 2M for SpaceXAI: Grok 4.20 Multi-Agent. 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 Claude Opus 5.5 and SpaceXAI: Grok 4.20 Multi-Agent support prompt caching?
Both publish a cached-input rate: $0.200 per million for Claude Opus 5.5 and $0.200 for SpaceXAI: Grok 4.20 Multi-Agent, against full input rates of $4.00 and $1.25. 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.