📌 Quick answer:

• Default to Sonnet 5.5 for scoped coding, bug fixes, drafting, and repeatable workflows. It costs half as much per token as Opus.
• Escalate to Opus 5.5 for ambiguous, multi-system work where a failed attempt is expensive.
• Context is not a reason to upgrade: both models offer a 1M-token context window and 128K maximum output.
• Pay 20% less than Anthropic's list price: Vidgo lists Sonnet 5.5 at $1.60 / $8 and Opus 5.5 at $3.20 / $16 per 1M tokens, versus $2 / $10 and $4 / $20 direct. PoYo matches those rates.

This guide compares Claude Sonnet 5.5 and Claude Opus 5.5, checked on October 13, 2026. Recommendations are editorial judgments based on Anthropic's published specifications and pricing, not our own benchmark. Vidgo publishes this guide.

Sonnet vs Opus at a glance

Sources: Anthropic's Sonnet 5.5 specifications, Opus 5.5 specifications and API pricing. These are direct Anthropic specifications; an intermediary may expose different limits, settings or tools.

A large repository or long report does not automatically require Opus. The question is whether Opus completes the task more successfully with the same evidence, tools and acceptance criteria.

Choose Sonnet 5.5 if… / Choose Opus 5.5 if…

Which model fits your work?

Choose Sonnet 5.5 for scoped coding and repeatable work

Sonnet is the first model we would evaluate for a reproducible bug fix, a feature with clear requirements, document drafting, or a support workflow with a defined answer rubric. A precise task gives you a concrete way to check the output and escalate only where necessary.

For example, “fix this failing pagination test without changing the public response schema” is easier to evaluate than “improve our backend.” Supply the relevant files and failing test, ask for a patch, and run the tests. If Sonnet meets the acceptance criteria consistently, paying Opus rates for every request adds cost without a demonstrated benefit for that workload.

Evaluate Opus 5.5 for ambiguous, longer tasks

Opus is worth a parallel evaluation when work spans multiple systems, requirements need interpretation, or a failed attempt creates substantial rework. Examples include tracing a bug through several services, assessing an architecture migration, or reconciling inconsistent evidence across documents.

Give both models the same tools and stop condition. Record whether they solve the problem, how many retries they need, and how much review remains. An Opus response that prevents an expensive failed release can justify its higher token rate. A longer response that repeats the same mistakes cannot.

Anthropic recommends Opus 5.5 as a general starting point in its model overview. Our Sonnet-first recommendation applies specifically to teams optimizing a measurable workflow for cost; teams prioritizing maximum initial capability can start with Opus.

Route routine requests to Sonnet and difficult cases to Opus

Escalate a failed test, unresolved contradiction or explicit user request using observable outcomes. Do not rely on a model's confidence statement as the only check. Preserve source material, test results and task state when escalating.

Anthropic notes that thinking blocks are tied to a model and conversation, so do not treat one model's thinking state as a portable cache for the other. The Sonnet and Opus migration notes explain the changes.

What does the request look like?
 │
 ├── Clear spec, failing test, or rubric ─────────────► 【Sonnet 5.5】
 ├── High volume, repeatable, budget-sensitive ───────► 【Sonnet 5.5】
 ├── Spans several systems or conflicting sources ────► 【Opus 5.5】
 ├── Sonnet failed the acceptance check ──────────────► 【Retry on Opus 5.5】
 └── Need maximum capability on the first attempt ────► 【Opus 5.5】

Pricing: compare the model and the platform separately

All figures are USD per 1M tokens, checked October 13, 2026. Input means ordinary uncached input. Output excludes separate hosted-tool charges. These are token-price comparisons, not identical task-cost guarantees: models can use different token counts for the same prompt.

A budget example you can reproduce

Assume 1,000 independent requests, each using 10,000 uncached input tokens and 2,000 billed output tokens, with no cache writes, batch discount or separately billed tools. That totals 10M input + 2M output tokens.

For this uncached workload, the listed Vidgo and PoYo rates produce a 20% lower token bill than standard direct pricing. This does not apply automatically to caching, batch processing, tools or different inference tiers.

On Vidgo, routing 900 requests to Sonnet and 100 to Opus gives 900 × $0.032 + 100 × $0.064 = $35.20. That assumes one attempt per request. Add escalation retries and actual output usage before treating it as a production forecast.

Account for caching separately

Cache reads and writes are separate billing items. An input/output discount does not establish a discount for every cache operation. Include the initial cache write, retention window and uncached portion of later requests when estimating the bill.

For Opus 5.5, the reviewed Vidgo and PoYo cache-read rate is $0.16/1M tokens, compared with $0.20/1M tokens at Anthropic's standard direct rate. This is a 20% cache-read saving under those specific rates. Keep this calculation separate from the uncached workload above.

API compatibility: changing the name is not the whole migration

Vidgo uses provider-qualified IDs: anthropic/claude-sonnet-5.5 and anthropic/claude-opus-5.5. Anthropic direct and PoYo use the hyphenated IDs shown earlier. Copy the identifier from the platform you are calling.

This minimal Vidgo Messages example follows the model-page format. It makes a text request without assuming native hosted-tool parity:

curl --request POST "https://api.vidgo.ai/v1/messages" \
  --header "x-api-key: $VIDGO_API_KEY" \
  --header "anthropic-version: 2023-06-01" \
  --header "Content-Type: application/json" \
  --data '{
    "model": "anthropic/claude-sonnet-5.5",
    "max_tokens": 4096,
    "messages": [{
      "role": "user",
      "content": "Review this retry policy. Identify duplicate-write risks and propose acceptance tests."
    }],
    "stream": false
  }'

See Vidgo's Claude Messages documentation and the Opus API panel before switching models. Keep API keys on your server. Chat returns a response or stream; it is not the media-generation submit-and-poll workflow.

Check three things when upgrading an agent:

1. Thinking and sampling: Opus 5.5 cannot disable thinking. Sonnet has its own adaptive controls; non-default sampling settings can be rejected. Remove inherited parameters that the model does not accept.
2. Tools: Forced tool use can return an error in these versions. Test tool-choice policy, schema validation and the tool-result loop against the exact endpoint.
3. Streaming: Text between tool calls can arrive in thinking blocks. A UI expecting only ordinary text deltas may stop showing progress while the agent keeps working.

These changes appear in the official Sonnet and Opus guides. Message-format compatibility does not guarantee every first-party tool or setting.

How to choose in a one-day evaluation

Take 20–50 representative tasks with sensitive data removed. Include easy requests, common failures, long inputs and tool errors. Write acceptance criteria before seeing the answers.

Run both models with the same files, tools and output limits. Make effort explicit when supported: their platform defaults differ. Compare successful completion, review minutes, retries, token spend and end-to-end time. Save provider, date and settings alongside results.

For coding, require a patch that passes tests and preserves the requested interface. For document work, verify cited statements and count material omissions. Choose the lower cost per accepted result, even when that model has a higher token price.

Frequently asked questions

Is Opus always better than Sonnet?

There is no universal winner. Opus targets longer, harder work; Sonnet is a cost-sensitive candidate for scoped tasks. Choose using acceptance results from your own workload.

Does Opus 5.5 have more context?

Both list 1M context and 128K normal maximum output. Special batch beta limits are separate from an ordinary synchronous request.

Is Sonnet 5.5 half the price of Opus 5.5?

For standard uncached input and output rates, yes. The ratio also holds for the Vidgo and PoYo base rates here. It does not mean every complete task costs exactly half as much.

Can I keep an OpenAI-compatible chat client?

The reviewed Vidgo and PoYo pages expose Chat Completions and Messages. Test tools, streaming and model-specific parameters; changing only the base URL and model name is not a complete compatibility test.

Should I move every request to Opus?

Only if its measured reduction in failures and review work justifies the total cost. A Sonnet default with explicit escalation is useful when difficulty varies.

Where does Claude Haiku fit in?

Vidgo's current Haiku listing is Claude Haiku 4.5, a previous-generation small model with a 200K context window. Consider it for classification, short answers, and simple routing in front of Sonnet, and test it before giving it coding work.

Compare both on your real tasks

Open Claude Sonnet 5.5 on Vidgo, then run difficult cases through Claude Opus 5.5. For a second route, compare PoYo's Claude API. Use the same acceptance criteria and compare the cost of a finished result.

Related reading: Best LLMs for coding in 2026 and best Claude alternatives.

Sources and verification

• Anthropic: Sonnet 5.5, Opus 5.5, pricing.
• Vidgo: Sonnet and API panel, Opus and API panel.
• PoYo: Sonnet and pricing, Opus and pricing. Checked October 13, 2026. Check current prices and account access before a larger rollout.