High-volume, cost-sensitive work
Choose Claude Sonnet 5.5
Claude Sonnet 5.5 costs 9% less on a typical mix of three input tokens for every output token ($4.00 against $4.38 per million tokens).
Claude Sonnet 5.5 vs GPT-4o: price, context and capabilities
Choose Claude Sonnet 5.5 for high-volume, cost-sensitive work, reused prompts and documents (RAG, agents), very long inputs, reasoning over long documents, the latest release and the most recent knowledge; on the other points the two are level or the data is missing.
In short
- Claude Sonnet 5.5 is 9% cheaper than GPT-4o at the headline price ($4.00 / 1M tokens vs $4.38 / 1M tokens).
- Claude Sonnet 5.5 reads more per request: 1M tokens against 128k.
- Claude Sonnet 5.5 is the newer model (September 2026, against May 13, 2024).
- Only Claude Sonnet 5.5 offers reasoning.
Which should you choose?
Each answer below comes straight from the published prices, specifications and independent benchmark results.
Reused prompts and documents (RAG, agents)
Choose Claude Sonnet 5.5
Claude Sonnet 5.5 charges $0.10 per million cached input tokens, against $1.25 for GPT-4o.
Very long inputs
Choose Claude Sonnet 5.5
Claude Sonnet 5.5 reads up to 1M tokens per request, against 128k for GPT-4o.
Reasoning over long documents
Choose Claude Sonnet 5.5
Claude Sonnet 5.5 scores 82.7% on Long-context reasoning (AA-LCR), against 49.3% for GPT-4o.
Latest release
Choose Claude Sonnet 5.5
Claude Sonnet 5.5 is the newer release (September 2026, against May 13, 2024 for GPT-4o).
Most recent knowledge
Choose Claude Sonnet 5.5
Claude Sonnet 5.5 was trained on data up to June 2026, against October 2023 for GPT-4o.
Monthly cost at three volumes
| Volume | Claude Sonnet 5.5 | GPT-4o | Difference |
|---|---|---|---|
| Prototype: 1M input, 250K output tokens | $4.50 | $5.00 | Claude Sonnet 5.5, $0.50 less |
| Production: 20M input, 5M output tokens | $90.00 | $100.00 | Claude Sonnet 5.5, $10.00 less |
| Scale: 500M input, 100M output tokens | $2,000 | $2,250 | Claude Sonnet 5.5, $250.00 less |
Standard rates, without caching or batch discounts. Volumes are per month.
Specifications side by side
| Claude Sonnet 5.5 | GPT-4o | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Category | Language models | Language models |
| Status | Generally available | Deprecated |
| Headline price | $4.00 / 1M tokens | $4.38 / 1M tokens |
| Input | $2.00 / 1M tokens | $2.50 / 1M tokens |
| Output | $10.00 / 1M tokens | $10.00 / 1M tokens |
| Cached input | $0.10 / 1M tokens | $1.25 / 1M tokens |
| Context window | 1M | 128k |
| Max output | 128k | 16k |
| Released | September 2026 | May 13, 2024 |
| Knowledge cutoff | June 2026 | October 2023 |
| Licence | Proprietary | Proprietary |
| Capabilities | Vision, Reasoning, Tool calling, Structured output, Prompt caching, Batch API | Vision, Tool calling, Structured output, Prompt caching, Batch API |
| API model id | claude-sonnet-5-5 | gpt-4o |
Benchmarks side by side
Leader in bold.
| Benchmark | Claude Sonnet 5.5 | GPT-4o |
|---|---|---|
| Humanity's Last Exam | 55% | 2.4% |
| Long-context reasoning (AA-LCR) | 82.7% | 49.3% |
| Intelligence Index | 56 | No data |
| SciCode | 61% | No data |
| Terminal-Bench Hard | No data | 8.3% |
| GPQA Diamond | No data | 54.3% |
| IFBench (instruction following) | No data | 34.3% |
| τ²-Bench (agentic tool use) | No data | 25.1% |
Independent evaluations by Artificial Analysis, run the same way for every model, at the reasoning setting shown. Percentages unless marked as an index.
Frequently asked questions
Should I choose Claude Sonnet 5.5 or GPT-4o?
Choose Claude Sonnet 5.5 for high-volume, cost-sensitive work, reused prompts and documents (RAG, agents), very long inputs, reasoning over long documents, the latest release and the most recent knowledge; on the other points the two are level or the data is missing.
Which is cheaper, Claude Sonnet 5.5 or GPT-4o?
Claude Sonnet 5.5 is 9% cheaper than GPT-4o at the headline price ($4.00 / 1M tokens vs $4.38 / 1M tokens).
Which has the larger context window, Claude Sonnet 5.5 or GPT-4o?
Claude Sonnet 5.5 reads more per request: 1M tokens against 128k.
What is the difference between Claude Sonnet 5.5 and GPT-4o?
Claude Sonnet 5.5 is made by Anthropic and GPT-4o by OpenAI. Claude Sonnet 5.5 is 9% cheaper than GPT-4o at the headline price ($4.00 / 1M tokens vs $4.38 / 1M tokens). Claude Sonnet 5.5 reads more per request: 1M tokens against 128k. Claude Sonnet 5.5 is the newer model (September 2026, against May 13, 2024). Only Claude Sonnet 5.5 offers reasoning.
How much do Claude Sonnet 5.5 and GPT-4o cost per month?
At 20 million input and 5 million output tokens a month, Claude Sonnet 5.5 costs $90.00 and GPT-4o costs $100.00, at standard rates.
Which is newer, Claude Sonnet 5.5 or GPT-4o?
Claude Sonnet 5.5 was released on September 2026 and GPT-4o on May 13, 2024.