Claude Opus 4.8 vs Grok 4.5 — Price, Context, and Capability Compared
Claude Opus 4.8 vs Grok 4.5: which should I use?
Claude Opus 4.8 costs 3.3× more per blended million tokens than Grok 4.5. Claude Opus 4.8 has the larger context window (500,000 tokens). Default to Grok 4.5 unless you specifically need Claude Opus 4.8's edge.
Price, speed, and task evidence
Task verdict
Best-fit task signals from the published model strengths; this is not a substitute for a controlled benchmark.
| Fact | Claude Opus 4.8 | Grok 4.5 |
|---|---|---|
| Best fit | Complex, multi-step tasks where Fable 5’s premium isn’t justified. | Agentic software engineering and workflow automation that need strong coding capability at a competitive price. |
| Reasoning mode | Available | Available |
Effective workload cost
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 4.8 | Grok 4.5 |
|---|---|---|
| Coding Agent / task | $0.15 (modeled) | $0.05 (modeled) (winner) |
| Input / output rate | $5.00 / $25.00 per M | $2.00 / $6.00 per M |
Speed
Only non-estimated benchmark results are shown as measured.
| Fact | Claude Opus 4.8 | Grok 4.5 |
|---|---|---|
| Measured throughput | 58 tokens/s | Unavailable |
| Time to first token | 470 ms | Unavailable |
API compatibility
Provider-level wire-format and SDK facts; model-specific parameter differences may still apply.
| Fact | Claude Opus 4.8 | Grok 4.5 |
|---|---|---|
| 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) |
Privacy and retention
Provider policy and residency facts from the verified provider registry. A missing retention policy is not treated as a guarantee.
| Fact | Claude Opus 4.8 | Grok 4.5 |
|---|---|---|
| Provider says API data trains models | No | Unavailable |
| Published retention period | Unavailable | Unavailable |
| Data residency | Unavailable | Unavailable |
Migration effort
Direction is from each displayed model to the other. Effort is derived from provider compatibility and published parameter maps.
| Fact | Claude Opus 4.8 | Grok 4.5 |
|---|---|---|
| Move Claude Opus 4.8 → Grok 4.5 | config; 3 breaking parameter differences | Target: Grok 4.5 |
| Move Grok 4.5 → Claude Opus 4.8 | Source: Grok 4.5 | 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. |
Spec comparison
| Claude Opus 4.8 | Grok 4.5 | |
|---|---|---|
| Price (input) | $5.00/M | $2.00/M ✓ |
| Price (output) | $25.00/M | $6.00/M ✓ |
| Blended price | $10.00/M | $3.00/M ✓ |
| Context window | 500,000 tokens | 500,000 tokens |
| Max output | 64,000 tokens | 64,000 tokens |
| Modalities | text, vision | text, vision |
| Reasoning mode | Yes | Yes |
| Released | 2026-04 | 2026-07 |
| Speed | 58 t/s | Not measured |
Cost at scale (3:1 blended)
| Tokens / month | Claude Opus 4.8 | Grok 4.5 | Delta |
|---|---|---|---|
| 1,000,000 | $10.00 | $3.00 | $7.00 (3.3×) |
| 10,000,000 | $100.00 | $30.00 | $70.00 (3.3×) |
| 100,000,000 | $1000.00 | $300.00 | $700.00 (3.3×) |
Choose Claude Opus 4.8 if…
- ✓Elite coding and multi-step reasoning
- ✓Strong instruction following on ambiguous prompts
- ✓Extended-thinking mode
- ✓Complex, multi-step tasks where Fable 5’s premium isn’t justified.
Choose Grok 4.5 if…
- ✓xAI coding model for agents and engineering
- ✓Configurable reasoning for complex tasks
- ✓500K-token context at $2/$6 per million tokens
- ✓Agentic software engineering and workflow automation that need strong coding capability at a competitive price.
Run this exact matchup right now
Send the same prompt to Claude Opus 4.8 and Grok 4.5 side by side and see the outputs yourself.
Try Claude Opus 4.8 vs Grok 4.5 FreeFAQ
Is Claude Opus 4.8 cheaper than Grok 4.5?
Grok 4.5 is cheaper, at $3.00 per million blended tokens vs $10.00 for Claude Opus 4.8.
Which has the bigger context window, Claude Opus 4.8 or Grok 4.5?
Both models support 500,000 tokens of context.
Can Claude Opus 4.8 replace Grok 4.5 for coding?
Both are viable for coding. Elite coding and multi-step reasoning (Claude Opus 4.8) vs xAI coding model for agents and engineering (Grok 4.5) — pick based on which strength matters more for your workload.
Neither of these? See Claude Opus 4.8 alternatives or Grok 4.5 alternatives.
Related
Pricing verified 2026-06-07. Specs verified 2026-08-14.