Claude Opus 5.5 vs Grok 4.3 — Price, Context, and Capability Compared
Claude Opus 5.5 vs Grok 4.3: which should I use?
Claude Opus 5.5 costs 5.1× more per blended million tokens than Grok 4.3. Claude Opus 5.5 has the larger context window (1,000,000 tokens). Default to Grok 4.3 unless you specifically need Claude Opus 5.5's edge.
Where can you find price, speed, and task evidence for Claude Opus 5.5 and Grok 4.3?
Which tasks fit Claude Opus 5.5 and Grok 4.3?
Best-fit task signals from the published model strengths; this is not a substitute for a controlled benchmark.
| Fact | Claude Opus 5.5 | Grok 4.3 |
|---|---|---|
| Best fit | The hardest reasoning, coding, and long-horizon agentic tasks. | General-purpose work where speed and a huge context window both matter. |
| Reasoning mode | Available | Available |
What does a Coding Agent workload cost with Claude Opus 5.5 and Grok 4.3?
Modeled for Coding Agent: 20,000 input + 2,000 output tokens per task, 1 turn. This is a workload model, not a provider quote.
| Fact | Claude Opus 5.5 | Grok 4.3 |
|---|---|---|
| Coding Agent / task | $0.12 (modeled) | $0.03 (modeled) (winner) |
| Input / output rate | $4.00 / $20.00 per M | $1.25 / $2.50 per M |
How fast are Claude Opus 5.5 and Grok 4.3?
Only non-estimated benchmark results are shown as measured.
| Fact | Claude Opus 5.5 | Grok 4.3 |
|---|---|---|
| Measured throughput | Unavailable | 98 tokens/s |
| Time to first token | Unavailable | 320 ms |
How compatible are Claude Opus 5.5 and Grok 4.3 with APIs?
Provider-level wire-format and SDK facts; model-specific parameter differences may still apply.
| Fact | Claude Opus 5.5 | Grok 4.3 |
|---|---|---|
| OpenAI SDK | Not drop-in | Usable |
| Request shape | Messages API — system prompt is a top-level field, not a message role, and max_tokens is required on every call. | Full OpenAI chat/completions compatibility — point the openai SDK at api.x.ai and it works unmodified. |
| Streaming | SSE (Anthropic content-block events) | SSE (OpenAI delta) |
What are the privacy and retention policies for Claude Opus 5.5 and Grok 4.3?
Provider policy and residency facts from the verified provider registry. A missing retention policy is not treated as a guarantee.
| Fact | Claude Opus 5.5 | Grok 4.3 |
|---|---|---|
| Provider says API data trains models | No | Unavailable |
| Published retention period | Unavailable | Unavailable |
| Data residency | Unavailable | Unavailable |
How much effort does it take to migrate between Claude Opus 5.5 and Grok 4.3?
Direction is from each displayed model to the other. Effort is derived from provider compatibility and published parameter maps.
| Fact | Claude Opus 5.5 | Grok 4.3 |
|---|---|---|
| Move Claude Opus 5.5 → Grok 4.3 | config; 3 breaking parameter differences | Target: Grok 4.3 |
| Move Grok 4.3 → Claude Opus 5.5 | Source: Grok 4.3 | code-change; 8 breaking parameter differences |
| Why | Keep the `openai` SDK; change `baseURL` and the API key. | Messages API — system prompt is a top-level field, not a message role, and max_tokens is required on every call. |
How do Claude Opus 5.5 and Grok 4.3 compare on specs?
| Claude Opus 5.5 | Grok 4.3 | |
|---|---|---|
| Price (input) | $4.00/M | $1.25/M ✓ |
| Price (output) | $20.00/M | $2.50/M ✓ |
| Blended price | $8.00/M | $1.56/M ✓ |
| Context window | 1,000,000 tokens | 1,000,000 tokens |
| Max output | 128,000 tokens ✓ | 64,000 tokens |
| Modalities | text, vision | text, vision |
| Reasoning mode | Yes | Yes |
| Released | 2026-09 | 2026-06 |
| Speed | Not measured | 98 t/s |
How much do Claude Opus 5.5 and Grok 4.3 cost at scale?
| Tokens / month | Claude Opus 5.5 | Grok 4.3 | Delta |
|---|---|---|---|
| 1,000,000 | $8.00 | $1.56 | $6.44 (5.1×) |
| 10,000,000 | $80.00 | $15.63 | $64.38 (5.1×) |
| 100,000,000 | $800.00 | $156.25 | $643.75 (5.1×) |
Choose Claude Opus 5.5 if…
- ✓Anthropic's strongest reasoning and coding
- ✓1M-token context
- ✓Extended-thinking mode for complex agentic work
- ✓The hardest reasoning, coding, and long-horizon agentic tasks.
Choose Grok 4.3 if…
- ✓xAI’s general-purpose flagship
- ✓Extremely fast for its size
- ✓1M-token context
- ✓General-purpose work where speed and a huge context window both matter.
Run this exact matchup right now
Send the same prompt to Claude Opus 5.5 and Grok 4.3 side by side and see the outputs yourself.
Try Claude Opus 5.5 vs Grok 4.3 FreeWhat are common questions about Claude Opus 5.5 and Grok 4.3?
Is Claude Opus 5.5 cheaper than Grok 4.3?
Grok 4.3 is cheaper, at $1.56 per million blended tokens vs $8.00 for Claude Opus 5.5.
Which has the bigger context window, Claude Opus 5.5 or Grok 4.3?
Both models support 1,000,000 tokens of context.
Can Claude Opus 5.5 replace Grok 4.3 for coding?
Both are viable for coding. Anthropic's strongest reasoning and coding (Claude Opus 5.5) vs xAI’s general-purpose flagship (Grok 4.3) — pick based on which strength matters more for your workload.
Neither of these? See Claude Opus 5.5 alternatives or Grok 4.3 alternatives.
What related comparisons help choose between Claude Opus 5.5 and Grok 4.3?
Pricing verified 2026-05-19. Specs verified 2026-08-14.