Choose Anthropic: Claude Sonnet 4 if…
No advantage on the data we track — pick it for provider preference or output quality on your own prompts.
Anthropic: Claude Sonnet 4 vs OpenAI: o3
OpenAI: o3 comes out ahead on the data we track: 4 advantages and none for Anthropic: Claude Sonnet 4.
Key numbers
| Spec | Anthropic: Claude Sonnet 4 | OpenAI: o3 |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Input price (per 1M tokens) | $3.00 | $2.00 |
| Output price (per 1M tokens) | $15.00 | $8.00 |
| Blended price (3:1 input/output) | $6.00 | $3.50 |
| Cheaper than … of all models we track | 8% | 17% |
| Context window | 200K tokens (~300 pages) | 200K tokens (~300 pages) |
| Larger context than … of all models | 37% | 37% |
| Max output per response | 64K tokens (~48,000 words) | 100K tokens (~75,000 words) |
| Input types | image, text, file | image, text, file |
| Output types | text | text |
| Free variant | No | No |
| Listed since | 2025-05-22 | 2025-04-16 |
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What it costs for real workloads
Monthly cost at list price for five common workloads. Token counts per unit are stated so you can scale them to your own traffic. A workload that does not fit a model's context window is marked rather than priced.
| Workload (per month) | Anthropic: Claude Sonnet 4 | OpenAI: o3 | Difference |
|---|---|---|---|
| Customer-support chatbot 50,000 conversations — each a 6-turn conversation (1,500 in / 400 out tokens) | $525 | $310 | OpenAI: o3 saves $215 |
| RAG search over documents 20,000 questions — each a question answered from ~8 retrieved passages (6,000 in / 500 out tokens) | $510 | $320 | OpenAI: o3 saves $190 |
| Coding / tool-using agent 2,000 tasks — each a multi-step task with tool calls and file context (60,000 in / 6,000 out tokens) | $540 | $336 | OpenAI: o3 saves $204 |
| Batch summarisation 10,000 documents — each a 6,000-word report summarised to a page (8,000 in / 600 out tokens) | $330 | $208 | OpenAI: o3 saves $122 |
| Long-document analysis 500 documents — each a 150-page contract or codebase read in one pass (100,000 in / 2,000 out tokens) | $165 | $108 | OpenAI: o3 saves $57.00 |
Capabilities side by side
| Capability | Anthropic: Claude Sonnet 4 | OpenAI: o3 | What it lets you do |
|---|---|---|---|
| Tool / function calling | ✓ Yes | ✓ Yes | call your APIs and run agent loops |
| Structured output (JSON schema) | — | ✓ Yes | return JSON that validates against your schema |
| Reasoning / thinking mode | ✓ Yes | ✓ Yes | spend extra tokens thinking before answering hard problems |
| Image input | ✓ Yes | ✓ Yes | read screenshots, charts and scanned pages |
| Audio input | — | — | take speech or audio directly |
| File / PDF input | ✓ Yes | ✓ Yes | accept documents without your own parsing step |
| Image output | — | — | generate images, not just text |
| Built-in web search | ✓ Yes | ✓ Yes | answer from live web results |
| Seed (reproducible sampling) | — | ✓ Yes | repeat a generation for tests and evals |
| Log-probabilities | — | — | read token confidence for classification and scoring |
From each model's published parameters and input/output types. “—” means not advertised, not proven absent.
Price history
- Anthropic: Claude Sonnet 4: price unchanged since we started tracking it on 2026-03-10.
- OpenAI: o3: price unchanged since we started tracking it on 2026-03-10.
Which should you choose?
Choose OpenAI: o3 if…
- cost matters at scale — it is 42% cheaper on a typical 3:1 input/output mix ($310 vs $525 a month for 50,000 support chats)
- you need structured output (JSON schema) — to return JSON that validates against your schema; Anthropic: Claude Sonnet 4 does not advertise it
- you need seed (reproducible sampling) — to repeat a generation for tests and evals; Anthropic: Claude Sonnet 4 does not advertise it
- you generate long outputs in one go — up to 100K tokens (about 75,000 words) per response
Frequently asked questions
Is Anthropic: Claude Sonnet 4 better than OpenAI: o3?
OpenAI: o3 comes out ahead on the data we track: 4 advantages and none for Anthropic: Claude Sonnet 4.
Which is cheaper, Anthropic: Claude Sonnet 4 or OpenAI: o3?
OpenAI: o3 is cheaper: $3.50 vs $6.00 per 1M tokens at a typical 3:1 input/output mix, 42% less. For 50,000 support conversations a month that is $310 against $525.
How much do Anthropic: Claude Sonnet 4 and OpenAI: o3 cost per million tokens?
Anthropic: Claude Sonnet 4 costs $3.00 per 1M input tokens and $15.00 per 1M output tokens; OpenAI: o3 costs $2.00 input and $8.00 output. Output tokens are billed separately, so long answers shift the gap.
Which has the bigger context window, Anthropic: Claude Sonnet 4 or OpenAI: o3?
Both take 200K tokens per request — roughly 300 pages of text.
Do Anthropic: Claude Sonnet 4 and OpenAI: o3 support function calling and JSON output?
Tool calling — Anthropic: Claude Sonnet 4: yes, OpenAI: o3: yes. JSON-schema structured output — Anthropic: Claude Sonnet 4: not advertised, OpenAI: o3: yes.
Can Anthropic: Claude Sonnet 4 or OpenAI: o3 read images?
Yes, both accept image input.
Is Anthropic: Claude Sonnet 4 or OpenAI: o3 free to use?
No free variant is listed for either; both are pay-per-token.
What is the maximum output length of Anthropic: Claude Sonnet 4 and OpenAI: o3?
Anthropic: Claude Sonnet 4 can write up to 64K tokens (about 48,000 words) per response; OpenAI: o3 up to 100K (about 75,000 words).
When were Anthropic: Claude Sonnet 4 and OpenAI: o3 released?
Anthropic: Claude Sonnet 4 was listed on 2025-05-22; OpenAI: o3 on 2025-04-16.
About the two models
Anthropic: Claude Sonnet 4
Claude Sonnet 4 significantly enhances the capabilities of its predecessor, Sonnet 3.7, excelling in both coding and reasoning tasks with improved precision and controllability. Achieving state-of-the-art performance on SWE-bench (72.7%),...
Full Anthropic: Claude Sonnet 4 specs →OpenAI: o3
o3 is a well-rounded and powerful model across domains. It sets a new standard for math, science, coding, and visual reasoning tasks. It also excels at technical writing and instruction-following....
Full OpenAI: o3 specs →