Originally published at claudeguide.io/claude-sonnet-4-6-vs-opus-4-7
Claude Sonnet 4.6 vs Opus 4.7: When to Pay 67% More for Opus (2026)
TL;DR. Opus 4.7 costs 67% more than Sonnet 4.6 on input and 67% more on output. That premium pays for itself on tasks that require deep multi-step reasoning, high-stakes code review, or long-horizon planning — but burns money on the 80% of workloads where Sonnet is already at ceiling. The decision rule is not "which model is smarter?" — it is "does this task hit Sonnet's ceiling?" If yes, Opus ROI is positive. If no, you are paying 67% for noise.
Pricing side-by-side
| Dimension | Sonnet 4.6 | Opus 4.7 | Delta |
|---|---|---|---|
| Input (per 1M tokens) | $3.00 | $5.00 | +67% |
| Output (per 1M tokens) | $15.00 | $25.00 | +67% |
| Cache write (per 1M) | $3.75 | $6.25 | +67% |
| Cache read (per 1M) | $0.30 | $0.50 | +67% |
| Context window | 200K | 200K | Same |
| Tool use | Yes | Yes | Same |
| Vision | Yes | Yes | Same |
The premium is uniform across all token types and cache tiers. There is no discount for switching to Opus only at the output layer — you pay the full premium on both sides.
At $1,000/month on Sonnet, the equivalent Opus workload costs $1,670/month — $670 more. That $670 delta is your ROI test: what does Opus win you that is worth $670/month?
Where Opus 4.7 pulls ahead of Sonnet 4.6
The performance gap is not uniform. Sonnet 4.6 reaches near-parity on deterministic tasks; Opus 4.7 separates on tasks requiring genuine reasoning chains.
| Task category | Sonnet 4.6 | Opus 4.7 | Gap |
|---|---|---|---|
| Simple classification / extraction | ~96% | ~97% | Negligible |
| Structured output (JSON, SQL) | ~93% | ~94% | Negligible |
| Short code completion | ~91% | ~93% | Small |
| SWE-Bench Verified (agentic coding) | ~62% | ~72% | +10 pp |
| Multi-step planning ( |
Migration checklist — adding Opus to an existing Sonnet stack
If you are currently routing everything to Sonnet and want to add Opus for high-complexity tasks:
Identify your complexity signals. What attributes of an incoming request correlate with Sonnet failures? Typical signals: task type, input length, presence of adversarial phrases, downstream criticality flag.
Canary the Opus route at 5%. Route by deterministic hash (request type + user ID). Do not random-sample — you need stable cohorts.
Measure quality delta, not just cost. Build a quality eval that captures what Opus should improve. If your eval does not detect the quality delta, your routing signal is probably wrong.
Watch output token drift. Opus 4.7 sometimes produces longer outputs than Sonnet 4.6 on the same prompt. Longer outputs mean higher cost. Cap
max_tokensexplicitly on all Opus endpoints.Implement a cost ceiling. Add per-request cost estimation and reject routing to Opus if the request would exceed a threshold (e.g., $0.50/request). Prevents runaway costs on adversarial inputs.
See claude-api-cost-monitoring-guide for the dashboard setup that makes this measurable.
Illustrative cost scenario
A research assistant agent running 25K tool-using requests per month, routed with the 80/15/5 rule versus all-Sonnet:
| Routing | Input cost | Output cost | Total/month |
|---|---|---|---|
| All Sonnet 4.6 | $75 | $375 | $450 |
| All Opus 4.7 | $125 | $625 | $750 |
| 80/15/5 (Haiku/Sonnet/Opus) | ~$30 | ~$150 | ~$180 |
The 80/15/5 routing delivers comparable quality to all-Sonnet at 60% less cost, and better quality than all-Sonnet on the 5% of complex requests where Opus matters.
Frequently Asked Questions
What is the latest Claude Sonnet model?
As of May 2026, the latest production Sonnet is Claude Sonnet 4.6 (claude-sonnet-4-6-20251120). The next step up in the Claude family is Opus 4.7 — there is no intermediate Sonnet release between 4.6 and Opus. Check Anthropic's model documentation for the current model list.
Can I switch between Sonnet and Opus mid-conversation?
Yes. The model parameter is per API call. You can use Sonnet for routine turns and Opus for specific steps in an agent loop. The conversation history format is identical across models.
Does prompt caching work the same way across both models?
Yes, but the cache is model-specific. A cached prefix for Sonnet 4.6 does not transfer to Opus 4.7. If you switch models within a session, the prefix must be rewarmed on the new model at cache-write rates. Budget for this if you route the same long system prompt across both tiers.
When would I use Haiku 4.5 instead of Sonnet 4.6?
Haiku 4.5 ($1/$5) is appropriate for tasks where the answer is short, deterministic, and does not require multi-step reasoning: classification, short extraction, translation, formatting. If you have a high-volume pipeline (millions of requests/month) on simple tasks, Haiku cuts cost by 67% vs Sonnet with negligible quality tradeoff.
What is Opus 4.1, and how does it compare?
Claude Opus 4.1 is a legacy model. Its legacy pricing was significantly higher than current Opus 4.7 rates ($5/$25 per 1M tokens). If you are still running Opus 4.1, migrating to Opus 4.7 saves 67% at the API line. There is no reason to stay on 4.1.
Related guides:
- Claude Haiku use cases guide — when Haiku is the right call
- Claude API cost monitoring guide — dashboards and alerts for model-tier routing
- Prompt caching cost benchmark — stacking caching with model tiering
→ Cost Optimization Masterclass — $59
30-day money-back guarantee. Instant download.
Top comments (0)